ServiceOrientedJavaBusinessIntegrationCopyright©2008PacktPublishingAllrightsreserved.Nopartofthisbookmaybereproduced,storedinaretrievalsystem,ortransmittedinanyformorbyanymeans,withoutthepriorwrittenpermissionofthepublisher,exceptinthecaseofbriefquotationsembeddedincriticalarticlesorreviews.

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CoverImagebyVinayakChittar(vinayak.chittar@gmail.com)

CreditsAuthor

BinildasC.A.

Reviewers

RajeshRV

RajeshWarrier

AcquisitionEditor

BansariBarot

DevelopmentEditor

VedPrakashJha

TechnicalEditor

DellaPradeep

EditorialTeamLeader

MithilKulkarni

ProjectManager

AbhijeetDeobhakta

ProjectCoordinator

AboliMendhe

Indexers

HemanginiBari

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Proofreader

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ProductionCoordinator

ShantanuZagade

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Coverwork

ShantanuZagade

AbouttheAuthorBinildasC.A.providesTechnicalArchitectureconsultancyforITsolutions.Hehasover13yearsofITexperience,mostlyinMicrosoftandSuntechnologies.DistributedComputingandServiceOrientedIntegrationarehismainstreamskills,withextensivehands-onexperienceinJavaandC#.NETprogramming.BinilholdsaBTech.degreeinMechanicalEngineeringfromCollegeofEngineering,Trivandrum(www.cet.ac.in)andanMBAinSystemsManagementfromInstituteofManagement,Kerala(www.imk.ac.in).Awell-knownandahighlysoughtafterthoughtleader,Binilhasdesignedandbuiltmanyhighlyscalablemiddle-tierandintegrationsolutionsforseveraltop-notchclientsincludingFortune500companies.HehasbeenpreviouslyemployedbymultipleITconsultingfirmsincludingIBSSoftwareServices(www.ibsplc.com)andTataConsultancyServices(www.tcs.com)andcurrentlyworksforInfosysTechnologies(www.infosys.com)asaPrincipalArchitectwhereheheadstheJ2EEArchitectsgroupservicingCommunicationsServiceProviderclients.

BinilisaSunCertifiedProgrammer(SCJP),Developer(SCJD),BusinessComponentDeveloper(SCBCD)andEnterpriseArchitect(SCEA),MicrosoftCertifiedProfessional(MCP)andOpenGroup(TOGAF8)CertifiedEnterpriseArchitecturePractitioner.HeisalsoaLicensedZapthinkArchitect(LZA)inSOA.BesidesTechnicalArchitectureBinil

alsopracticesEnterpriseArchitecture.

Whennotinsoftware,BinilspendstimewithwifeSowmya&daughterAnnin'God'sOwnCountry',Kerala(www.en.wikipedia.org/wiki/Kerala).BinildoeslongdistancerunningandisanationalmedalistinPowerLifting.YoumaycontactBinilatbiniljava@yahoo.co.inorbinil_christudas@infosys.com.

AcknowledgementFirstandForemost,IwouldthankGodwhohasalwaysshoweredhischoicestblessingsonme.IthankHimforallthathehasdoneforme.

IwouldliketothankPACKTandeveryoneIworkedwith—PriyankaBaruah,BansariBarot,PatriciaWeir,AboliMendhe,BhushanPangaonkar,VedPrakashJha,DellaPradeepandothers.TheyworkedveryhardwiththeaggressivescheduleIproposedonthisbook,andItrulydoappreciatetheircontributions.

Next,I'dliketothanktheTechnicalReviewersofourbook,RajeshR.V.andRajeshR.Warrier.Withoutthem,youwouldn'tseethetextasitappearshere.Thankyouforyourthoroughreviewofthescriptsandtestingofthecode.Yourreviewswereveryobjectiveinpointingoutissuesandhelpingmetocomeupwiththeevenbetterchapters.

ThisbookwouldhaveneverbeenpossibleifwereitnotfortheexcellentcolleaguesatIBS(otherthanthereviewers)whomIhaveworkedwithandlearnedfrom.ThemostimportantofthemarePrasanthGNair,ShyamSankarS,SherryCK,JayanPandAmrithaMathewM.ThanksareduetoVKMathewsforprovidingallofustheopportunity.IwouldalsoliketothankRajasekharC.andAjmalKhanwhoprovidedmetherightchallengesattherighttime.

SpecialthanksareduetoDr.SrinivasPadmanabhuni,PrincipalResearcher,WebServices/SOACentreofExcellence,SoftwareEngineeringandTechnologyLabs,Infosysforhisguidanceandhelp.

IwouldliketothankmywifeandbestfriendSowmyaforbeingaconstantsourceofinspirationinmylife.AlsomysweetlittledaughterAnn,Irememberallthosemomentswhenyouweresodesperatetoplaywithmeandtogooutfor'dinner'withpappaandamma,butIcouldnotlookbeyondmylaptopscreen.Bothofyouaremyangels,thanksforeverything,especiallyforbeinginmylife.

AmassivethanksmustgotomyMomandDad—AzhakammaandChristudas—whohavesupportedtheirwaywardsonthroughgoodandleantimes,andhavegiveneverythingandaskedfornothing.Ithanktherestofmyfamilyfortheirsupportandfriendship—mysisterBinithaandfamily,mywife'smother,Pamala,andfatherHubertfortheirunconditionalencouragementandloveinhelpingmefindtheenergytocompletethisbook.

IwouldalsoliketothankRamavarmaRforsupportingmethroughhisconsultancy,MacJavaB.

Thereweremanyotherswhoplayedtheirparttoo.Mostimportantofthemarethecreatorsoftheframeworksthathaveinspiredmetowritethisbook.ThankyoufortheJBIspecificationandspecialthankstotheServiceMixdeveloperandusercommunity.

Last,it'snecessarytothankyou,thereader,forchoosingtobuythisbook.IunderstandthatyouhaveaspecificintentioninchoosingtoreadthisbookandIhopeItakeonlytheminimumrequiredtimefromyourbusyschedulestoserveyourrequirements.

AbouttheReviewersRajeshRVreceivedhisComputerEngineeringdegreefromtheUniversityofCochin,India.HejoinedtheJEEcommunityduringtheearlydaysofEJB(1.0)andfullydedicatedhistimeincoretechnicalactivitiesinandaroundJava,JEE.Duringthecourseasasolutionarchitect,hehasworkedonmanylargescalemissioncriticalprojects,includingtheNewGenerationPassengerReservationSystem(400+ManYears)andNextGenerationCargoReservationSystem(300+ManYears),intheAirlinedomain.RajeshisalsoSunCertifiedJavaEnterpriseArchitectandBEACertifiedWeblogicAdministrator.

RajeshiscurrentlyworkingwithEmiratesAirlinesITDivisionbasedinDubaiandhisworkismainlyinConsulting,ApplicationFrameworkdevelopment,TechnologyEvaluationsandSOArelatedtopics.

AllmythanksgoestomywifeSarithaforsupportingmeandlovingmeeventhoughIbookedalotofpersonaltimetoreviewthisbook.

RajeshWarrier,currentlyworkingasoneoftheleadsystemarchitectsinEmiratesGroupIT,hasaround10yearsexperienceintheindustryworkingwithcompanieslikeSunMicrosystems.Hehasbeenresponsibleforarchitectinganddesigningmanymissioncriticalenterpriseapplicationsusing

cuttingedgetechnologies.Heiscurrentlyworkingasanarchitectandmentorforthenewgenerationcargosystemfortheemiratesairlines,developedcompletelyusingJEE.

PrefaceYou'reallinthebusinessofsoftwaredevelopment.Someofyouarearchitectsanddeveloperswhilefewothersaretechnologymanagersandexecutives.Formanyofyou,ESBisencroachingandJBIisstillanunknown—ariskpreviouslyavoidedbutnowfoundtobeinescapable.LetustamethesebuzzwordsinthecontextofSOAandIntegration.

Whileyoudothedaytodayprogrammingforsolvingbusinessproblems,youwillbegeneratingbusinesscodeaswellasbusinessintegrationcode.ThetraditionalJava/J2EEAPIsprovideyouwithenoughtoolsandframeworkstodothebusinesscoding.Thebusinesscodewillhelpyoutoimplementabusinessservicesuchascreatingordersorfindingproducts.Onthecontrary,businessintegrationcodewirestogethermultipleapplicationsandsystemstoprovideseamlessinformationflow.Itdealswithpatternsofinformationexchangeacrosssystemsandservices,amongotherthings.ThisiswherethenewJavaAPIforIntegration—JavaBusinessIntegration(JBI)seeksattention.

JBIprovidesacollaborationframeworkwhichhasstandardinterfacesforintegrationcomponentsandprotocolstopluginto,thusallowingtheassemblyofServiceOrientedIntegration(SOI)frameworksfollowingtheEnterpriseServiceBus(ESB)pattern.JBIisbasedonJSR208,whichisanextensionofJava2EnterpriseEdition(J2EE).Thebookfirst

discussesthevariousintegrationapproachesavailableandintroducesESB,whichisanewarchitecturalpatternwhichcanfacilitateintegratingservices.Indoingso,wealsointroduceServiceMix,anApacheOpenSourceJavaESB.Thusforeachofthesubsequentchapters,welimitourdiscussiontoamajorconcernwhichwecanaddressusingESBandthenalsoshowcasethiswithsampleswhichyoucanrunusingServiceMix.Ifyouareapersonwithanon-Javabackground,thebookstillbenefitsyousincemostoftheintegrationwiringhappensinXMLconfigurationfiles.

TheaimofthisbookistoprepareanarchitectordeveloperforbuildingintegrationsolutionsusingESB.Tothatend,thisbookwilltakeapracticalapproach,emphasizinghowtogetthingsdoneinServiceMixwithcode.Onoccasions,wewilldelveintothetheoreticalaspectsofESB,andsuchdiscussionswillalwaysbesupplementedwithenoughrunningsamples.Thebook,thus,attemptstodistillsomeoftheknowledgethathasemergedoverthelastdecadeintherealmofJavaIntegration.Quitedifferentfromtheotherbooksintherelatedtopics,youdon'tneeda4GBRAMorsomeheavy,vendorspecificIDE/Workshopstorunthesamples.Instead,getsetwiththelatestJDKandatexteditorandfewotherlightweightframeworksincludingTomcatandyouarereadytogo.Enoughaboutthehype,supplementwithwhatyou'veheardwithsomesubstanceandcode.

HappyReading!

WhatThisBookCoversChapter1beginswithaquicktouronEnterpriseIntegrationandtheassociatedissuessothatyoucanbetterunderstandtheproblemwhichwearetryingtosolve,ratherthanfollowingasolutionforanunknownproblem.WealsointroduceEnterpriseServiceBus(ESB)architectureandcompareandcontrastthatwithotherintegrationarchitectures.

Chapter2introducesJavaBusinessIntegration(JBI)andinspectstheneedforanotherstandardforBusinessIntegration,andalsolooksintothedetailsonwhatthisstandardisallabout.

Chapter3introducesServiceMix,whichisanopensourceESBplatformintheJavaprogramminglanguage,builtfromthegroundupwithJBIAPIsandprinciples.ItrunsthroughafewotherESBproductsalso.

Chapter4looksathowwehavebeenbindingserviceslocallyorremotelyevenbeforetheESBbecamepopular.ThechapterwilldemonstratehowtunnelingusingconventionalJ2EEtoolswillhelptoexposeeventechnology-specificAPIservices.AnexampleofsuchaserviceisanEJBservicetobeexposedthroughfirewallsoverHTTPsothattheservicebecomestechnologyagonistic.

Chapter5introducesXFire,whichisanewgenerationJava

SOAPframeworktoeasilyexposewebservices.HerewedemonstratetheintegrationcapabilitiesoftheXFire.ThenwecandointegrationusingXFirewithintheJBIArchitecturealso.

Chapter6teachesyouJBIpackaginganddeployment.Aftergoingthroughthischapterthereaderwillbeabletobuild,package,anddeployintegrationartifactsasstandardJBIpackagesintotheJBIcontainer.

Chapter7teachsyouhowtocreateyourowncomponentsanddeploythemontotheJBIcontainer.ThischaptervisitsthecoreAPIfromtheServiceMixaswellasfromtheJBIspecificationwhichwillfunctionasusefulhelperclassesusingwhichyoucandevelopintegrationcomponentsquickly.

Chapter8showsyouhowtobindEnterpriseJavaBeanscomponentstotheESB.EJBistheDistributedComponentparadigmintheJava-J2EEworldandtheindustryhasalotinvestedinthistechnology.CoexistingserviceswiththosecomponentswillhelpyoutoreusethoseexistinginvestmentssothatwecancontinuebuildingnewsystemsbasedonhigherlevelsofSOAmaturity.

Chapter9showsPOJOBindingusingJSR181totheESB.POJOcomponentscanbeeasilyexposedasWSDL-compliantservicestotheJBIbus.

Chapter10illustrateshowtobindthewebservicestotheServiceMixESB,thuscreatingawebservicesgatewayattheESBlayer.

Chapter11looksathowJavaMessageService(JMS),whichisaplatformdependentmessagingtechnology,canincreasetheQOSfeaturesofwebservicesbymakingwebservicesaccessiblethroughtheJMSchannel.

Chapter12introducesJavaXMLbindingandXStream,whichisasimpleopensourcelibrarytoserializetheJavaobjectstoXMLandbackagain.WewillshowtheXStreamintegrationwithESBdemonstratingstreamingofdataacrossthebus.

Chapter13visitstheJDKProxyclassesandthenexplainstheJBIProxyindetailwithexamples.WeshowapracticaluseoftheJBIProxy—ProxyingtheexternalwebservicesintheJBIbus.

Chapter14explainsversioningintheSOAcontextandexplainsvariousstrategiesandapproachestoversioningservices.ItalsoexplainsanddemonstratesaversioningsampleleveragingthetargetNamespaceattribute.Versioningservices,especiallyversioningofwebservices,isatopicofheateddiscussioninmanyforumsandsites.

Chapter15explainsthattheEAIpatternsarenuggetsofadvicemadeoutofaggregatingbasicMessageExchangePatternelementstosolvefrequentlyrecurringintegrationproblems.WecanlookatEAIpatternsasdesignpatternsforsolvingintegrationproblems.ThischapterwilldemonstratemanyofthecommonEAIpatterns.

Chapter16looksintoasampleusecase.OneoftheusefulapplicationsofESBistoprovidea"ServicesWorkbench"

whereinwhichwecanusevariousintegrationpatternsavailabletoaggregateservicestocarryoutthebusinessprocesses.

Chapter17visitsafewselectedQOSfeaturessuchasTransactions,Security,Clustering,andManagementwhichcanimpacttheprogramminganddeploymentaspectsusingESB.

WhatYouNeedforThisBookToinstallandrunmostofthesamplesmentionedinthisbookallyouneedisthefollowing:

LatestJavaSDK(JDK)installedinyourmachine.

ApacheOpenSourceEnterpriseServiceBus—ServiceMix.

ApacheAntbuildtool.

Asimpletexteditor,likeTextpad.

Anyothersoftwarerequiredismentionedwhichisdownloadablefreefromthenet.

WhoisThisBookforThisbookisaimedatJavadevelopersandintegrationarchitectswhowanttobecomeproficientwithJavaBusinessIntegration(JBI)standard.TheyareexpectedtohavesomeexperiencewithJavaandtohavedevelopedanddeployedapplicationsinthepast,butneednopreviousknowledgeofJBI.ThebookcanalsobeusefultoanyonewhohasbeenstrugglingtounderstandESBandhowitdiffersfromotherarchitecturesandtounderstanditspositioninSOA.

ThisbookprimarilytargetsITprofessionalsinthefieldofSOAandIntegrationsolutions—inotherwords,intermediatetoadvancedusers.Youarelikelytofindthebookusefulifyoufallintoanyofthefollowingcategories:

Aprogrammer,designerorarchitectinJavawhowantstolearnandcodeinJBIorESB.

Aprogrammer,designerorarchitectwhodoesn'tnormallycodeinJavacanstillbenefitfromthisbook,sincewe'assembleintegrationcomponents'usingXMLwithlittletonoJavacode.

AnITManageroranOfficerwhoknowswellaboutSOAorSOIbutwanttoseesomethingincode(youcanadornyourflashypresentationswithsomelivecodetoo).

ConventionsInthisbook,youwillfindanumberofstylesoftextthat

distinguishbetweendifferentkindsofinformation.Herearesomeexamplesofthesestyles,andanexplanationoftheirmeaning.

Therearethreestylesforcode.Codewordsintextareshownasfollows:"Forexample,insidethe<component>tagyoucanconfigurepropertiesonthecomponent."

Ablockofcodewillbesetasfollows:

<targetname="run">

<javaclassname="HttpInOutClient"fork="yes"

failonerror="true">

<classpathrefid="classpath">

<arg

value="http:/localhost:8912/EsbServlet/hello/">

<argvalue="HttpSoapRequest.xml">

</java>

</target>

Anycommand-lineinputandoutputiswrittenasfollows:

cdch03\Servlet

ant

Newtermsandimportantwordsareintroducedinabold-typefont.Wordsthatyouseeonthescreen,inmenusordialogboxesforexample,appearinourtextlikethis:"Thecomponentsbeinginitialized,inourcase,includetrace,timer,httpGetData,andhttpReceiver."

NOTENOTE

Importantnotesappearinaboxlikethis.

NOTENOTE

Tipsandtricksappearlikethis.

ReaderFeedbackFeedbackfromourreadersisalwayswelcome.Letusknowwhatyouthinkaboutthisbook,whatyoulikedormayhavedisliked.Readerfeedbackisimportantforustodeveloptitlesthatyoureallygetthemostoutof.

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Ifthereisatopicthatyouhaveexpertiseinandyouareinterestedineitherwritingorcontributingtoabook,seeourauthorguideonwww.packtpub.com/authors.

CustomerSupportNowthatyouaretheproudownerofaPacktbook,wehavea

numberofthingstohelpyoutogetthemostfromyourpurchase.

DownloadingtheExampleCodefortheBookVisithttp://www.packtpub.com/files/code/4404_Code.zip,todirectlydownladtheexamplecode.

Thedownloadablefilescontaininstructionsonhowtousethem.

ErrataAlthoughwehavetakeneverycaretoensuretheaccuracyofourcontents,mistakesdohappen.Ifyoufindamistakeinoneofourbooks—maybeamistakeintextorcode—wewouldbegratefulifyouwouldreportthistous.Bydoingthisyoucansaveotherreadersfromfrustration,andhelptoimprovesubsequentversionsofthisbook.Ifyoufindanyerrata,reportthembyvisitinghttp://www.packtpub.com/support,selectingyourbook,clickingontheSubmitErratalink,andenteringthedetailsofyourerrata.Onceyourerrataareverified,yoursubmissionwillbeacceptedandtheerrataareaddedtothelistofexistingerrata.Theexistingerratacanbeviewedbyselectingyourtitlefromhttp://www.packtpub.com/support.

Questions

Youcancontactusatquestions@packtpub.comifyouarehavingaproblemwithsomeaspectofthebook,andwewilldoourbesttoaddressit.

Chapter1.WhyEnterpriseServiceBusToday'senterpriseisnotconfinedtothephysicalboundariesofanorganization.OpensystemsandanopenITinfrastructurestrivestoprovideinteroperabilitynotonlybetweenplatforms,runtimes,andlanguages,butalsoacrossenterprises.Whenourconcernsshiftfromnetworkedsystemstonetworkedenterprises,awholelotofopportunitiesopenuptointeractwithenterpriseapplications.Whetheritisfortradingpartnerstocollaboratethroughtheirback-endsystems,orformultichanneldeploymentswhereconsumerscanuseawholelotofuseragentslikewebandmobilehandsets,theopportunitiesareendless.Thisalsointroducestheissuesandconcernstobeaddressedbynetwork,integration,andapplicationarchitects.Today,companiesthathavebeenbuiltthroughmergersorrapidexpansionshaveLineofBusinesses(LOB)andsystemswithinasingleenterprisethatwerenotintendedtointeracttogether.Moreoftenthannottheseinteractionsfailandarediscredited.

Let'sbeginwithaquicktourofenterpriseintegrationandtheassociatedissuessothatwecanbetterunderstandtheproblemwhichwearetryingtosolve,ratherthanfollowasolutionforanunknownproblem.Attheendofthischapter,youshouldbeinapositiontoidentifywhatwearetryingtoaimwiththisbook.WealsointroduceEnterpriseServiceBus(ESB)

architecture,andcompareandcontrastitwithotherintegrationarchitectures.ThenwecanbetterunderstandhowJavaBusinessIntegration(JBI)helpsustodefineESB-basedsolutionsforintegrationproblems.

Inthischapterwewillcoverthefollowing:

Problemsfacedbytoday'senterprises

EnterpriseApplicationIntegration(EAI)

Differentintegrationarchitectures

ESB

Compareandcontrastservicebusandmessagebus

NeedforanESB-basedarchitecture

Boundary-LessOrganizationJackWelch,ofGeneralElectric(GE),inventedtheboundary-lessorganization.Meaningthat,organizationsshouldnotonlybeboundary-less,butshouldalsobemadepermeable."Integratedinformation"and"integratedaccesstointegratedinformation"aretwokeyfeaturesthatanyenterpriseshouldaimfor,inordertoimprovetheirorganizationalbusinessprocesses.Boundary-lessdoesn'tmeanthatorganizationhasnoboundaries;itmeansthatthere'sasmoothandefficientflowofinformationacrossboundaries.Whileenterpriseportalsandwebservicesgiveanewfaceforthisemergingparadigm,theskeletonofthis"openenterprise"isprovidedbyanopenITinfrastructure.ThefleshisprovidedbyemergingtrendsinEnterpriseApplicationIntegration(EAI)practice.

Letusbrieflyvisitafewselectedissuesfacedbytoday'senterprises.

MultipleSystemsInahomebusinessorinsmallscaleventures,westartupwithsystemsandapplicationsinsiloswhichcatertotheentiresetup.Whenthebusinessgrows,weaddmoreverticals,whicharefunctionallyseparatedentitieswithinthesameorganization.Itgoeswithoutsayingthat,eachoftheseverticalsorLOBwillhavetheirownsystems.Peopleaskwhytheyhavedifferentsystems.Theanswerisbecausetheyaredoingfunctionallydifferentoperationsinanenterpriseandhencetheyneedsystemscarryingoutdifferentfunctionalityforthem.Forexample,anHRsystemwillmanageandmaintainemployeerelateddatawhereasthemarketingrelationswilluseCustomerRelationshipManagement(CRM)systems.ThesesystemsmaynotbeinterconnectedandhenceimpedeinformationflowacrossLOBs.Addingtothis,eachLOBwillhavetheirownbudgetingandcostconstraintswhichdeterminehowoftensystemsareupgradedorintroduced.

NoCanonicalDataFormatMultipleLOBswillhavetheirownsystems,andhencetheirowndataschemas,andawayofaccessingthedata.Thisleadstoduplicationofdata,whichinturnleadstomultipleservicesprovidingviewsforthesameentityindifferentways.

Let'sconsidertheexampleshowninthefollowingfigure.

ThereisoneLOBsystem,ProductInformationSystem,whichwillkeeptrackofcustomerswhohaveregisteredtheirinterestforaparticularproductorservice.AnotherLOBsystem,EventRegistrationSystem,willprovidemembershipmanagementtoolstocustomers,forasalesdiscountprogram.SalesInformationSystemwillhavetotrackallcustomerswhohaveregisteredtheirinterestforanyupcomingproductsorservices.Thus,wecanseethereisnounifiedviewoftheCustomerentityattheenterprise-level.EachLOBwillhaveitsownsystemsandtheirownviewofCustomer.SomewillhavemoreattributesfortheCustomer,whileothersafew.NowthequestioniswhichsystemownstheCustomerentity?Rather,howdoweaddressthedatastewardshipissue(Thisisrepresentedinthefigureusingthesymbols"?"and"?")?

NOTENOTE

Datastewardshiprolesarecommonwhenorganizationsattempttoexchangedata,preciselyandconsistently,betweencomputersystems,andreusedata-relatedresourceswherethestewardisresponsibleformaintainingadataelementinametadataregistry.

Autonomous,butFederatedNowthequestionishowlongcanthesesystemsremain

isolated?Rather,canwebringallthesesystemsunderacentral,singlepointofcontrol?Thefactis,systemscannotremainisolated,andalsotheycannotbecontrolledcentrally.Thisisbecauseeverysystemneedsdatafromevery(ormost)othersystems.Canwethenintegrateeverythingtogetherintoasinglebigsystemsothatwedon'thavetheproblemofintegrationatall?Thequestionseemstempting,butthisisanalogoustoattemptingtoboilseawater.

Differentdepartmentsorverticalswithinthesameorganizationneedautonomyandsodotheirsystems.Withouttherequiredlevelofautonomy,thereisnofreedomwhichwillhinderinnovation.Constantinnovationisthekeytosuccess,inanywalkoflife.So,departmentsandtheirsystemsneedtobeautonomous.But,sincetheyrequireeachother'sdata,theyneedtointegrate.Thisleadstothenecessityforafarmofautonomoussystems,whichareallfederatedtotherequiredleveltofacilitateinformationflow.

Thefollowingfigurerepresentssystemsthatareautonomous,butfederatedtofacilitateinformationflow:

IntranetversusInternetIntegratingdifferentfunctionaldepartmentswithinanorganizationisnotabighurdle,sinceeverythingisunderthecontroloftheorganization.Butthepicturechangesthemomenttheorganizationgrowsbeyondacertainlimit.Twentyfirstcenturyorganizationsaregrowingbeyondasinglelocation;manyofthemaretrulyglobalorganizations.Theyhaveoperationsaroundtheglobe,inmultiplecountries,withmultiplelegal,technical,andoperationalenvironments.ThegoodnewsisthatwehavetechnologieslikeInternet,WideAreaNetworks,andVirtualPrivateNetworksforconnectivity.Thismeansglobalorganizationswillhavetheirsystemsfederatedacrosstheglobe.Allthesesystemswillevolveduetoconstantinnovationandbusinesschanges.Theyhavetointegrateacrossthefirewall,andnoteveryprotocolandformatcanbeeasilytraversedacrossthefirewall.

TradingPartnersOrganizationsconductbusinesswithotherorganizations.Anonlineretailer'ssystemhastopartnerwithitswholesaler'sinventorysystems.Thesesystemsarenotfederatedinanymannerduetothefactthattheybelongtomultipleorganizations.Thereexistsnofederationduetothecompetitivenaturebetweenorganizationstoo.Buttheyhavetocollaborate;otherwisethereisnobusinessatall.So,informationhastoflowacrossorganizationalsystemsintheInternet.Thisiswhatwemeanbyapermeableorganizationboundarywhichallowsforconstantinformationexchangeon

24X7bases,withadequateQualityofService(QOS)features.Thusthenecessityistoextendtheenterpriseovertheedge(firewall),andthisactivityhastohappenbasedonpre-plansandnotasanafterthought.

ThefollowingfigureexplainsatradingpartnerssystemthatisnotfederatedbuttheinformationflowisthroughtheInternet:

IntegrationKnowinglyorunknowingly,applicationsandsystemshavebeenbuiltoverdecadesinsilos,anditistheneedofthedayfortheseapplicationsandsystemstointerchangedata.Atvariouslevelsdependinguponthelevelofcontrol,thedatacanbeinterchangedatmultiplelayers,protocols,andformats.

Thereseemstobeageneraltrendof"Technologyoftheday"solutionsandsystemsinmanyorganizations.Neitherthistrendisgoingtoend,nordoweneedtoturnbackatthem.Instead,weneedtomanagetheeverchangingheterogeneitybetweensystems.

NOTENOTE

Applicationandsystemportfolioentropyincreaseswithtechnologyinnovation.

Idon'tknowifthereisaglobalmovementtobringstandardizationtoinnovationintechnology.Thisisbecausethemomentweintroducerulesandregulationstoinnovation,itisnolongeraninnovation.Thisstatementismade,evenafteracknowledgingvariousworldwidestandardbodies'aimandefforttoreducesystemandapplicationentropy.Afewyearsback,CommonObjectRequestBrokerProtocol's(CORBA)promisewastostandardizebinaryprotocolinterfacesothatanysystemscouldinteroperate.IfwelookatCORBAatthispoint,wecanseethatCORBAhasnotattaineditspromise,thatdoesn'tmeanthatweneedtothrowawayallthosesystemsintroducedduringthe90'sbecausewecannotintegrate.

EnterpriseApplicationIntegrationDavidS.LinthicumdefinedEAIas:

Theunrestrictedsharingofdataandbusinessprocessesamonganyconnectedapplicationsanddatasourcesinthe

enterprise.

Thisisasimple,straightforwarddefinition.Inmyentirecareer,IhavebeenfortunateenoughtoparticipateinmuchnewgenerationITsystemdevelopmentfordomainssuchasAirline,Healthcare,andCommunications.Mostofthetime,I'vebeenwritingeitheradaptersbetweensystems,ornegotiatingandformalizingdataformatsbetweendesperatesystems.Iknowthisisnotbecausetheformersystem'sarchitectshaven'tputalongtermvisiontotheirsystemsintheangleofinteroperability,butbecausesystemshavetoevolveandinteroperateinmanynewwayswhichwerenotforeseenearlier.Thispushesintegrationproviderstodefinenewsoftwarepipesacrossapplications.Whenwestartthisactivityitmightbeelegantandstraightforward,butsoonerthanlaterwerealizethatourintegrationpipeshavenocentralcontrol,administration,ormanagementprovisions.

IntegrationArchitecturesThefirstandforemoststepinunderstandingintegrationarchitecturesistounderstandthedifferenttopologiesexistinginintegrationarena,andtoappreciatethevitaldifferencebetweenthem.Ifonecanunderstandthetruedifference,halfthejobisalreadydone.Understandingthedifferencewillenabletheintegrationarchitecttoattachprescriptivearchitectureforagivenintegrationproblem.Letusnowunderstandthebasicintegrationarchitecturesthatarelistedasfollows:

Point-to-Pointsolution

Hub-and-Spokesolution

EnterpriseMessageBusIntegration

EnterpriseServiceBusIntegration

Point-to-PointSolutionEAIhastraditionallybeendoneusingpoint-to-pointintegrationsolutions.Inpoint-to-point,wedefineanintegrationsolutionforapairofapplications.Thuswehavetwoendpointstobeintegrated.Wecanbuildprotocoland/orformatadapters,ortransformersatoneoreitherend.Thisistheeasiestwaytointegrate,aslongasthevolumeofintegrationislow.Wenormallyusetechnology-specificAPIslikeFTP,IIOP,remotingorbatchinterfaces,torealizeintegration.Theadvantageisthatbetweenthesetwopoints,wehavetightcoupling,sincebothendshaveknowledgeabouttheirpeers.

Thefollowingfigureisthediagrammaticrepresentationofthepoint-to-pointintegration:

Hub-and-SpokeSolutionHub-and-spokearchitectureisalsocalledthemessagebrokerandissimilartopoint-to-pointarchitectureinthatitprovidesacentralizedhub(broker)towhichallapplicationsareconnected.Whenmultipleapplicationsconnectinthismanner,wegetthetypicalhub-and-spokearchitecture.Anotherdistinguishingfeatureofthehub-and-spokearchitectureisthateachapplicationconnectswiththecentralhubthroughlightweightconnectors.Thelightweightconnectorsfacilitatesforapplicationintegrationwithminimumornochangestotheexistingapplications.Messagetransformationandroutingtakesplacewithinthehub.Thisarchitectureisamajor

improvementtothepoint-to-pointsolutionsinceitreducesthenumberofconnectionsrequiredforintegration.Sinceapplicationsdonotconnecttootherapplicationsdirectly,theycanberemovedfromtheintegrationtopologybyremovingfromthehub.Thisinsulationreducesdisruptionintheintegrationsetup.

Thereisamajordrawbackwiththehub-and-spokearchitecture.Duetothecentralizednatureofthehub,itisasinglepointoffailure.Ifthehubfails,theentireintegrationtopologyfails.Asolutiontothisproblemistoclusterthehub.Aclusterisalogicalgroupingofmultipleinstancesrunningsimultaneouslyandworkingtogether.Butclusteringisnottherightsolutiontotheproblemofsinglepointoffailure.Thisisduetothefactthattheverypointinhavingahub-and-spokearchitectureistohaveasinglepointofcontrol.Thisdrawbackmaybeoffsettosomeextentbythefactthatmostoftheclusteringsolutionsprovidecentralmanagementandmonitoringfacilities,whichwillprovidesomeformofcentralizedcontrol.

Thefollowingfigureisthediagrammaticrepresentationofthehub-and-spokeintegration:

EnterpriseMessageBusIntegrationWhilethehub-and-spokearchitecturemakesuseoflightweightconnectorsforapplicationstointegratetogetherthroughacentralhub,manyatimestheintegratingapplicationsneedtointeractinadecoupledfashion,sothattheycanbeeasilyaddedorremovedwithoutaffectingtheothers.Anenterprisemessagebusprovidesacommoncommunicationinfrastructure,whichactsasaplatform-neutralandlanguage-neutraladapterbetweenapplications.

Thiscommunicationinfrastructuremayincludeamessagerouterand/orPublish-Subscribechannels.Soapplications

interactwitheachotherthroughthemessagebuswiththehelpofrequest-responsequeues.Ifaconsumerapplicationwantstoinvokeaparticularserviceonadifferentproviderapplication,itplacesanappropriatelyformattedrequestmessageontherequestqueueforthatservice.Itthenlistensfortheresponsemessageontheservice'sreplyqueue.Theproviderapplicationlistensforrequestsontheservice'srequestqueue,performstheservice,andthensends(if)anyresponsetotheservice'sreplyqueue.

WenormallyusevendorproductslikeIBM'sWebsphereMQ(WMQ)andMicrosoftMQ(MSMQ),whicharethebestclassmessagequeuesolutiontointegrateapplicationsinthemessagebustopology.Asshowninthefollowingfigure,sometimestheapplicationshavetouseadapterwhichhandlescenariossuchasinvokingCICStransactions.SuchanadaptermayprovideconnectivitybetweentheapplicationsandthemessagebususingproprietarybusAPIs,andapplicationAPIs.TheMessagebusalsorequiresacommoncommandstructurerepresentingthedifferentpossibleoperationsonthebus.Thesecommandsetsinvokebus-levelprimitiveswhichincludeslisteningtoanaddress,readingbytesfromanaddress,andwritingbytestoanaddress.

EnterpriseServiceBusIntegrationTheservicebusapproachtointegrationmakesuseoftechnologystackstoprovideabusforapplicationintegration.Differentapplicationswillnotcommunicatedirectlywitheachotherforintegration;insteadtheycommunicatethroughthismiddlewareServiceOrientedArchitecture(SOA)backbone.ThemostdistinguishingfeatureoftheESBarchitectureisthedistributednatureoftheintegrationtopology.MostESBsolutionsarebasedonWebServicesDescriptionLanguage(WSDL)technologies,andtheyuseExtensibleMarkupLanguage(XML)formatsformessagetranslationandtransformation.

ESBisacollectionofmiddlewareserviceswhichprovidesintegrationcapabilities.ThesemiddlewareservicessitintheheartoftheESBarchitectureuponwhichapplicationsplacemessagestoberoutedandtransformed.Similartothehub-and-spokearchitecture,inESBarchitecturetoo,applicationsconnecttotheESBthroughabstract,intelligentconnectors.Connectorsareabstractinthesensethattheyonlydefinethe

transportbindingprotocolsandserviceinterface,nottherealimplementationdetails.Theyareintelligentbecausetheyhavelogicbuilt-inalongwiththeESBtoselectivelybindtoservicesatruntime.Thiscapabilityenhancesagilityforapplicationsbyallowinglatebindingofservicesanddeferredservicechoice.

ThefollowingfigureisthediagrammaticrepresentationofESBintegration:

TheabovequalitiesofESBprovidesforatrueopenenterpriseapproach.Aswehavediscussedabove,ESBisneitheraproductnoraseparatetechnology;instead,ESBisaplatform-levelconcept,asetoftools,andadesignphilosophy.What

thismeansis,ifwejustbuyavendorproductandinstallitinourITinfrastructure,wecannotsaythatwehaveESB-basedintegrationarchitecture.InsteadESB-basedintegrationsolutionsaretobedesignedandbuiltinthe"ESBway".Toolsandproductshelpustodothis.

AlistofmajorfeaturesandfunctionalitiessupportedbyanESBwillhelpustounderstandthearchitecturebetter,whicharelistedasfollows:

Addressingandrouting

Synchronousandasynchronousstyle

Multipletransportandprotocolbindings

Contenttransformationandtranslation

Businessprocessorchestration

Eventprocessing

Adapterstomultipleplatforms

Integrationofdesign,implementation,anddeploymenttools

QOSfeaturesliketransactions,security,andpersistence

Auditing,logging,andmetering

Managementandmonitoring

EnterpriseServiceBusversusMessageBusLet'sleavealonethepoint-to-pointandthehub-and-spokearchitectures,sinceitisrathereasytounderstandthemandyouhavebeendoingtheminonewayoranother.Butwhen

wediscussaboutESBandmessagebus,weneedtounderstandthesimilaritiesanddifferencesbetweenthesetwotopologies.

SimilaritiesandDifferencesLetusfirstseehowthemessagebusandtheservicebusarealike.Infact,bothofthemareaimedtosolvetheproblemofintegrationandprovideacommoncommunicationinfrastructure,whichactsasaplatform-neutralandlanguage-neutraladapterbetweenapplications.Somediationistheprimefunctionalityprovidedbyboththearchitectures.Applicationscanintegrateeachotherinalooselycoupledmannerthroughthismediator,sothattheywillnotbedependentoneachother'sinterfaces.Lastbutnottheleast,usingeitherthemessagebusortheservicebusarchitecture,youcanimplementSOA-basedintegrationsolutions!

Thelaststatementmightbehardtodigest—atleastsomeofyoumighthavethoughtthatoneispurelySOA-basedwhiletheotherisnot.ButthefactisthatboththemessagebusandtheservicebushelpsenterprisestoattainanSOAecosystem,ifarchitectedproperly,butneitherofthembyitselfwillautomaticallytransferexistingnon-SOAarchitectureintoSOA-basedarchitecture.

Now,whatisthedifferencebetweenamessagebusandaservicebus?

Beforewedigintothedifferencesletmegiveyouawordof

caution.Eventhoughthemaindifferencesbetweenamessagebusandaservicebuswillbelistedasfollows,theymaynotbeveryobviousinthefirstread.Hence,Irecommendthereadertogothroughthesubsequentchaptersandsamplestoo,andgetafeelofhowwedothingsinthe"ESBway",andthenrevisitthegivendifferences.

NOTENOTE

Themaindifferencebetweenenterprisemessagebusandenterpriseservicebusarchitectureisinthemannerinwhichtheconsumerortheclientapplicationinteractwiththemessagingmiddleware.

Moreeasilysaid,thanunderstood!OK,letusworryless(Ididn'tsay"letusworrynot"!),understandmore.

ServicedescriptionandservicediscoveryaretwokeyelementstoattainhigherlevelsofSOAmaturity.Onlyifsomethingisdescribed,canitbediscovered.Thisiswhereaserviceregistryisgoingtoaddvalue,thereyoucanregisteraservicedescriptionsothatsomeotherinterestedpartycandiscoverit.

Letusnowcomebacktoourmessagebus.Weearliersawthatmessagebusapplicationsinteractwitheachotherwiththehelpofrequest-responsequeues.Ifyouhaveeverworkedinanymessagingsolution(likeJMS)before,thenyouwillappreciatethefactthatqueuesareaddressedbythemselves,whichwillnotgiveyouanyfurtherinformationabouttheunderlyingservice.Informationontheoperationsavailable,orthemessagingpatternstoexpect,ortheschemaforthetypesexchangedisneveravailableatthequeue-level.Inother

words,servicesarenotdescribedinamessagebus.

Whatisavailableisjustthemessagingcounterpartsfortheputandgetprimitivessothatmessagescanbesenttoandreceivedfromthemessagebus.Soconsumerorclientapplicationsshouldhavepre-awarenessoftheformatofthemessagesexchanged.Thisimplieseverythinghastobeknownbeforehand—rather,staticbindingorcompile-timebindingbecomesthenorm.

Letusnowconsidertheservicebus.WesaidearlierthatmanyESBsolutionsarebasedonWSDLtechnologies,andtheyuseXMLformatsformessagetranslationandtransformation.Thisbyitselfgivesuslotofopportunitiesforservicedescriptionanddiscovery.Allthe(minimum)detailsabouttheservicewillbeavailablefromtheWSDL.Hence,messageexchangepatternsandmessageformatsarereadilyavailable.Moreover,theconsumerorclientapplicationscandiscoveramatchingservicefromtheESB,givenasetofmessagingcapabilities(WSDLcapabilities)theyarelookingfor.IusedthetermmatchingservicebecauseinanidealESBarchitecturetheconsumerislookingforcapabilitieswhichmatchtheirabstractserviceexpectations(interface).ItistheroleoftheESBtoroutetherequeststoanyconcreteserviceimplementationbehindthebuswhichmatchestherequestedinterface.

Thenextbigdifferenceisthetypeofapproachusedineacharchitecture.Inservicebusarchitectureweusedastandard-basedapproach.WhenservicesareWSDL-based,itbringsatimetestedandwelladoptedindustrystandardtointegration.ThishasabigpayoffwhencomparedtotraditionalMessage

OrientedMiddleware(MOM),becauseinthemessagebusarchitecturetheadaptersprovideconnectivityusingproprietarybusAPIsandapplicationAPIs.So,whereasinthepre-ESBworld,wehavebeenusingCORBAIDL(InterfaceDefinitionLanguage),orTuxedoFML(FieldManipulationLanguage),orCOM/DCOMMicrosoftIDL,andCICScommonArea(COMMAREA)astheservicedefinitionlanguage,wenowuseWSDLastheinterfaceinstandard-basedESBarchitectures.

MaturityandIndustryAdoptionHavinglookedatafewofthesimilaritiesanddifferencesbetweenservicebusandmessagebus,itistimenowtolookatrealitieswhichexistintheindustrytoday.WeagreedthatanESBcandolotmanythings,andforthatmatteramessagebuscantoo.Wethentalkedaboutthedifferencesaservicebushastooffer.

Howmatureisthetechnologytodaytoaddressthesedifferences?Havewestartedpracticalimplementationsofservicebusinabigwayyet?Theanswertothisquestionisneitheryesnorno.Thereasonisthatnecessityrunsbeforestandards.Rather,whenyouagreethatyouneeddescriptionanddiscoveryalongwithotherfeaturesforaservicebus-basedarchitectures,thequestionis,willtheexistingstandardslikeUniversalDescriptionDiscoveryandIntegration(UDDI)alonewillhelptoachievethis?Maybeweneedasimpleandstandardwaytospecifyapairofrequest-replyqueuesalongwithaHTTPURL(mechanismtospecifyHTTPURLis

alreadyavailable)intheWSDLitself.Thiswayaconsumerorclientapplicationcaninteractinthe'MOMway'throughtheESB.Maybewealsoneedasimpleand,again,astandardwaytofindandinvokeaconcreteserviceattheESB,matchinganabstractserviceinterface.

Thesestandardsareevolvingandareatdifferentstagesofadoption.Similaristhecaseofsupportforthesecapabilitiesacrossmultiplevendors'solutions.Hence,thetailpieceisthatitistimenowtogatherallourexperienceinmessagebusbasedarchitectures,andleverageittodefineanddemonstrateservicebus-basedarchitecture.So,howdowedecidethatweneedanESB-basedArchitecture?Readonthenextsectionandyouwillcometoknow.

MakingtheBusinessCaseforESBJustlikeanyoneofyou,IamnotsatisfiedyetwithenoughreasonsforwhytouseESB.Hence,thissectionisgoingtoexplainmoreaboutthevaluepropositionESBisgoingtobringtoyourITinfrastructure.

Thereareafewconcernsweneedtoaddresswhenwedopoint-to-pointorasimilarstyleofintegration:

Howmanychannelsdoweneedtodefineforcompleteinteroperability?

Howeasyitistochangeasysteminterface,whilestillmaintaininginteroperability?

HowdoweaccommodateanewsystemtotheITportfolio?

Howmuchwecanreusesystemservicesinthistopology?

Wheredoweplug-insystemmanagementormonitoringfunctionality?

Letusaddresstheseissuesonebyone.

HowmanyChannelsLetusgobacktothepoint-to-pointintegrationscenarioandassumethatwehavefourseparatein-housesystems,oneforeachofthefourseparatedepartments(HR,Accounts,R&D,andSales).Theoperationalproblemthebusinessfacesistointeroperatethesesystems.Inthepoint-to-pointintegration,weneedtohaveindependentchannelsofconnectionbetweeneachpairofsystems.Thesechannelsarestatic,stronglytyped,andwithoutmuchintelligencefordynamicroutingortransformation.Theadvantageisthatitisrathereasytobuildthesolution.

Asshowninthenextfigure,iftherearesixsystems(nodes)tobeinterconnected,weneedatleastthirtyseparatechannelsforbothforwardandreversetransport.IfweaddonemorenodetotheITportfolio,thenumberofchannelstobedefinedgoesupfromthirtytofortytwo.Thismeans,astimepassesandasmoreandmoresystemsandapplicationsareaddedtotheorganization,thenumberofinterconnectionsorchannelstobedefinedbetweenthesesystemsrisesexponentially,intheorderoftwo.

Wecangeneralizethenumberofchannels(Nc)requiredfor

completeinterconnectionfornseparatesystemsas:

Nc=n -n

Thisnumberisstillmanageableforsmallorganizationswithasmallnumberofsystems,butexperiencehasshownthatthisisgoingtobeanightmareformid-sizedandlarge-sizedorganizations.Itiscustomaryforsuchorganizationstohavemorethanfiftyorhundredsystems.Forcompleteinteroperabilityinahundredsystemscenario,weneedtodefinearoundtenthousandseparatechannels!Leavealonethedefinition,howdowemaintainsuchahugenetworkofinterconnection?

2

Perhaps,everysysteminanorganizationneedn'tinteroperatewitheveryothersystem.Again,experiencehasshownthatonlyhalfofthemneedtointeroperatefully,thusbringingdownthefiguretofivethousand.Whatthismeansis,wehavetobuildfivethousandadapterstodefinechannelstointeroperateforthesesystems.Stillthisnumberisnotmanageable.

VolatileInterfacesInaperfectworld,wecansomehowbuildfivethousandseparateadapterstointerconnectahundredsystemsbyfiftypercent,andthenhopetorelax.Buttherealscenarioisfarfromperfect.Theimperfectionarisesoutofconstantinnovationandevolution,andthisforceschangeeventosysteminterfaces.AnintdatatypeinC++isoftwobyteswhereasthesameintinJavaisoffourbytes.Wehavealreadytakencareofthisdataimpedancebybuildingadapters.But,whatifononefinemorning,theC++applicationstartsspittingfloatinsteadofint?Theexistingadapterisgoingtofail,andweneedtoreworkontheadapterinthischannel.

Thegoodnewsis,withinanorganizationthiscanbecontrolledandmanagedsincewehaveaccesstoboththeendsoftheadapter.ThescenarioworsenswhentheinterfacechangesinaB2Bscenariowheresystemsbetweentwoseparateorganizationsinteract.Asweknowalready,thisisgoingtohappen.So,wehavetobuildagileinterfaces.

NewSystemsIntroducingDataRedundancyAddingnewsystemsisanaftereffectofbusinessexpansion,buttherearemultiplerisksassociatedwithit.First,weneedtointegratenewsystemswiththeexistingsystems.Secondly,manyatime,newsystemsintroducedataredundancy.Thisisbecausethesamedatamightgetenteredintothenetworkthroughmultipleinterfaces.Similaristheproblemofthesamedataduplicatedatdifferentpartsoftheorganization.ThiscontradictstherequirementsofStraight-ThroughProcessing(STP).STPaimstoentertransactionaldataonlyonceintothesystem.Thisdatacanflowwithinoroutsidetheorganization.ToachieveSTP,thereshouldbemechanismforseamlessdataflow,alsoinaflexiblemanner.

DataredundancycanbemanagedifandonlyifthereisamechanismtoconsolidatedataintheformofCommonInformationModel(CIM).Forexample,theNGOSS'sSharedInformation/Data(SID)modelfromTelecomManagementForumistheindustry'sonlytruestandardfordevelopmentanddeploymentofeasytointegrate,flexible,easytomanageOSS/BSScomponents.TheSIDprovidesaninformationordatareferencemodelandacommoninformationordatavocabularyfromabusinessandsystemsperspective.Noteverydomainororganizationhasaccesstoareadymadeinformationmodelsimilartothis.

Insuchascenario,ESBcanplayavitalrolebyprovidingtheedgeofthesystemviewbywrappingandexposingavailablenetworkresources.Thus,ESBprovideshooksfora"leave-

and-layer"architecturewhichmeansthatinsteadofalteringexistingsystemstoprovideastandards-basedservicesinterfacetheyarewrappedwithalayerthatprovidestheservicesinterface.

ServiceReuseCodeandcomponentreuseisafamiliarconceptamongstdesignersanddevelopers.WehaveGangofFourpatternstoprescribedesignsolutionsforrecurringproblems.ButwiththeinventionofSOA,wehavewhatiscalledtheServiceOrientedIntegration(SOI)whichmakesuseofEnterpriseIntegrationPatterns(EIP).SOIspeaksaboutthebestwaysofintegratingservicessothatservicesarenotonlyinteroperablebutalsoreusableintheformofaggregatinginmultiplewaysandscenarios.Thismeans,servicescanbemixedandmatchedtoadapttomultipleprotocolsandconsumerrequirements.

Incodeandcomponentreuse,wetrytoreducecopyandpastereuseandencourageinheritance,composition,andinstancepooling.AsimilaranalogyexistsinSOIwhereservicesarehostedandpooledformultipleclientsthroughmultipletransportchannels.ESBdoesexactlythisjobinthebestwayintegrationworldhaseverseen.Forexample,ifafinancialorganizationprovidesacredithistorycheckservice,anESBcanfacilitatereuseofthisservicebymultiplebusinessprocesseslikeaPersonalLoanapprovalprocessoraHomeMortgageapprovalprocess.

SystemManagementandMonitoringCrosscuttingconcernsliketransactionsorsecurityorevenServiceLevelAgreement(SLA)managementandmonitoringarejustafewofasetoffeaturesapartfrombusinessfunctionalitythatanyenterpriseclassserviceecosystemhastoprovide.TheESBarchitecturesprovidesenoughhookstoattachsimilarservicesontothebusseparatefromnormalbusinessfunctionality.Thisensuresthatthesecrosscuttingfunctionalitycanbeappliedtoallservicesandalsoenableustomanage,monitor,andcontrolthemcentrally.

EnterpriseServiceBusHavingunderstoodthevariousintegrationproblems,whichcanbeaddressedinmultipleways,ofwhichESBisoftheprimeconcernandiscentraltoourdiscussioninthisbook,wewilltrytounderstandtheESBbetterhere.

ServiceinESBItistimenowtounderstand"Service"inESB.Whydon'twecallitEnterpriseComponentBus?

Servicesareexposedfunctionalitieswhichareclearlydefined,selfcontained,andwhichwillnotdependonthestateandcontextofpeerservices.Asshowninthefollowingfigure,theservicehasaservicedescription(similartoWSDL)anditis

thisdescriptionwhichisexposed.Itisnevernecessarytoexposetheimplementationdetails,andinfact,weshouldn'texposethem.Itisthishiddennatureoftheimplementationwhichhelpsustoreplaceserviceswithsimilarservices.Thus,serviceprovidersexposetheservicedescriptionandserviceconsumersfindthem.

Oncetheservicedescriptionisfoundserviceconsumerscanbindtoit.Moreover,itisduringthetimeofactualbinding,weneedmoreinformationliketransportprotocols.Asweknow,wecanhandlewithtransportdetailswiththehelpofprotocoladapters.Intelligentadaptersarerequiredifweneedtoroutemessagesbasedoncontentorcontext.Theseadaptersareofadifferentkindlikesplittersandcontentbasedrouters.ESBisallaboutaruntimeplatformforthesekindsofadaptersandrouters,whicharespecificallydesignedforhostingandexposingservices.

AbstractionbeyondInterfaceAlmostallOOPlanguagessupportinterface-driven

developmentandhencethisisnotanewconcept.SeparatinginterfacefromimplementationabstractstheServiceConsumerfromtheimplementationdetailsfromaServiceProviderperspective.But,whataboutabstractingoutthisinterfaceitself?IftheServiceConsumerinteractsdirectlywiththeServiceProvider,boththesepartiesaretightlycoupledanditmaybedifficulttochangetheinterface.Instead,aservicebuscaneffectivelyattachitselftoaserviceregistry.Thismeans,aconsumercanevenbeunawareoftheserviceinterface.

Now,justintime,theconsumercanselectivelychooseanappropriateinterfacefromaregistry,thenbindtoasuitableimplementationthroughanESB,andinvoketheserviceatruntime.Suchkindsofflexibilitycomeatthecostofdesigntimeorcompiletimetypechecking,whichcanbeerrorproneduringserviceinvocationusingconventionaltools.AnESBwithitssetoftoolsanddesignprimitiveshelpsdeveloperstoeffectivelyaddressthis.

ServiceAggregationThekeyvalueofaggregation,here,isnotsomuchinbeingabletoprovidecoreservices,whichdevelopershavetobuildanyway.Itistofacilitateanarbitrarycompositionoftheseservicesinadeclarativefashion,soastodefineandpublishmoreandmorecompositeservices.BusinessProcessManagement(BPM)toolscanbeintegratedoverESBtoleverageserviceaggregationandservicecollaboration.Thisfacilitatereuseofbasicorcore(orfinegrained)servicesatthebusinessprocess-level.So,granularityofservicesisimportant

whichwillalsodecidethelevelofreusability.

CoarseGrainedorCompositeServicesconsumeFineGrainedServices.ApplicationswhichconsumeCoarseGrainedServicesarenotexposedtotheFineGrainedServicesthattheyuse.CompositeServicescanbeassembledfromCoarseGrainedaswellasFineGrainedServices.

Tomaketheconceptclear,letustaketheexampleofprovisioninganewVOIPServiceforanewcustomer.ThisisaCompositeServicewhichinturncallsmultipleCoarseGrainedServicessuchasvalidateOrder,createOrVerifyCustomer,andcheckProductAvailability.Now,createOrVerifyCustomer,theCoarseGrainedServiceinturncallmultipleFineGrainedServiceslikevalidateCustomer,createCustomer,createBillingAddress,andcreateMailingAddress.

Asisshownintheabovefigure,aCompositeServicesisanaggregateofotherCompositeServicesand/orCoarseGrainedServices.Similarly,CoarseGrainedServicesareagainaggregatesofotherFineGrainedServices.Whereas,FineGrainedServicesimplementminimumfunctionalityandarenotaggregatesofotherservices.ESBhereactsasasharedmessaginglayerforconnectingapplicationsandotherservicesthroughouttheenterprise,thusprovidingaworkbenchfor

serviceaggregationandcomposition.

ServiceEnablementServicescanbedesignedbutifleftalonetheywillsitidle.TheideabehindtrueSOAisnotjustservicedefinitionorimplementation,butalsoserviceenablement.Byserviceenablement,wemeanenabling,configuring,tuning,andattachingQOSattributestoservices,sothattheyareaccessible,asperSLAirrespectiveofformatsortransportprotocols.

Usingtoday'stechniqueslikeAspectOrientedProgramming(AOP),Annotationsandbytecodeinstrumentation,serviceenablementcanbedonewithoutanydependencyontheservicesframework.AnESBdoesexactlythis.ItistobenotedthataJBI-basedESBwilldothisAPI-less.ItisnotcompletelyAPI-less,inthesensethatthereisalwaysadependencyonanXMLconfigurationorannotation.Thedifferentiatingfactoristhatthisdependencyisexternalizedsothattheyarenotcementedtotheserviceimplementation.

ServiceConsolidationServiceconsolidationisanimportantsteptoeliminateredundantinformationanddata.Asapartofserviceconsolidation,wemayhavetofirstconsolidateITinfrastructureanddataassetsinthenetwork.Thereshouldbeclearownershipforthesetwoentities,sothatweknowwhoorwhichapplicationsarechangingwhichsectorsofthedata

assets.Oncethisisdone,thenextstepistodoapplicationportfolioanalysisanddodirectmappingbetweenservicesanddataoperations(business-levelCRUD).

ApointtobenotedhereisthatIamnottalkingaboutexposingsimpleCreate,Read,Update,andDeleteoperationstobeexposedasservices,sincetheyarenot(coarsegrained)servicesatall.Theyarejustfunctionstoaltertheconstantsofdatamodelandifweexposethemasservices,wearetryingtoexposeourinternaldatamodeling,whichisgoingtoimpactinternalagility.Instead,whatwehavetoexposeisourcoarsegrainedbusinessoperations(processes)whichcarryoutusefulbusinessfunctionsonbehalfofclientapplications.Whenwedothat,wecanmapwhichservicesneedtobeinvokedtofinishanonlineretailingexperience,andwhichotherservicesareresponsibleforrealizingtheretailbookinginthebackofficesystems.

Thusservicesarenamed,labeled,andallthemoreindexed.Andyoulookattheindexforaparticularservicesimilartothewayyoulookatabookindex,tofindaparticularsubject.Thus,weeffectivelypoolservicesandconsolidateunusedcapacityformerlyspreadovermanyconnectedsystemsandservers.

ServiceSharingMessagebusfacilitatesservicesharingascomparedtoservicereuse.InfactservicesharingisoneofthekeyaspectsofSOA.

Inservicereuse,thesameserviceishostedindifferentdeploymentenvironmentsduetovariousreasons.Eventhoughthecomponentorthecodebehindtheserviceisreusedhere,thereissignificantoverheadintermsofdeployment,management,andmaintenance.TheServicereusescenarioisasshowninthefollowingfigure:

Servicesharingis,incontrast,thetruesharingofaserviceitself.Thismeanstheservicehostingenvironmentisconfiguredfordifferentscenariosandconsumersaccessthesameserviceinstancethroughmultiplechannelsorformats.SOAwebservicescanbeleveragedtoachievethis,andthisisfurtherenabledusingamessagebusasshowninthefollowingfigure:

LinkedServicesMicrosoftSQLServerhastheabilitytoqueryremotedatabaseobjectsasiftheywerelocaltotheserver.Linkedserversareusefulindeployments,wherethedatacanbesplitbyfunctionalareaintodatabaseswithverylittlecouplingasameansofscaleoutstrategy.Thismeansthatascaledoutdatabasecanlooklikeasinglelargedatabasetoanapplication.Similartothis,ESBcanbeseenasameanstolinkservices.Bindingtoremoteendpointsissynonymoustolinkingtoremotedatabases—anapplicationcodecaninteractwiththelinkedservicesasiftheywerelocaltotheinvokingcode.

VirtualizationofServicesByservicevirtualization,Imeandividingtheorganization'sinformationassetsinto"VirtualServices"withoutregardtothetransportorbindingprotocoloftheactualimplementationcomponents.Corporatenetworkassets(information)canresideinmultipleplaceslikeinacentralizedmainframeordistributedacrossmultiplesystemsimplementedusingDCOM,RMI,IIOP,remoting,orSOAPprotocols.

Servicewrappingandserviceaggregationaretwomethodsbywhichwecanvirtualizethemtobeexposedinaconsistentwaytoexternalorinternalclients.Thus,virtualizationiscloselyrelatedto"blackbox"reuseofservicesbyprovidingadifferentinterfaceatthesameabstraction-level.TheESBabstractsbehindthesceneaddressing,translations,andaggregation.

Well-definedinterfacesfacilitatedevelopmentofinteractingsoftwaresystemsnotonlyindifferentLOBs,butalsoatdifferenttimes,thusprovidingasuitableabstractionforanyconsumersoftheservice.Butabstractionhasanegativesidetoo—softwaresystems,components,orservicesdesignedforoneinterfacewillnotworkwiththosedesignedforanotherinterface.This,infact,isaninteroperabilityissuewhichcanbeaconcern,especiallyinaworldofnetworkedcomputerswherethetrendistomovedataandinformationfreely.

Servicevirtualizationisawaytocircumventthisissuebymappingthevisibleinterfaceofaserviceontotheinterfaceandresourceofanunderlying,possiblydifferent,realservice.

ThisfiguredepictstheconceptofServiceVirtualization,wherewemakeuseofcoreESBfeatureslikeAggregation,Routing,andTranslationtorepublishtheexistingserviceassets.Theseareexplainedindetailinsubsequentchapters.

ServicesFabricWe,integrationpeople,needtolearnlessonsfromthewaynetworkarchitectsorganizetheirnetworkchannels.Whenusingfiber,networkarchitectshavethreenetworktopologies.Forthefibrechanneloption,wehavethreenetworktopologiesviaanyfromthefollowinglist:

Point-to-point

Arbitratedloop

Fabric

Inthefabrictopology,thereareoneormorehardwareswitchesinadditiontoportsoneachdevicetonetwork.Comparatively,inESBwehaveintelligentadapters.MultipleclientscanhittheESBfabric,andintelligentadaptersattheESBedgeareresponsiblefordynamicbindingofclient

requeststoappropriateconcreteserviceimplementations.Thus,ESBservicesfabricfunctionsasthevirtualizationlayer.Inotherwords,theESBprovidesinfrastructurecapabilitiesandapplicationplug-inpointsforanSOAfabricforthewholeenterprise.

SummaryInformationintegrationisasoldasInformationTechnology(IT)itself.Wehavebeendoingitinmultiplewaysandusingmultipletechnologystacks.But,whatismoreimportantisthat,attheendoftheday,theintegratedsolutionshouldbesolvingmoreexistingproblemsandintroducinglessnewproblems.ThisiswhereselectingandchoosingappropriateintegrationarchitectureismostimportantintheITlandscape.

WehaveseenwhatESBarchitectureisandhowitisdifferentfromotherpeerintegrationarchitectures.Sofarsogood,andtoday,youcanreadanynumberofdocumentsonESBfromtheInternet.We,asarchitectsanddevelopersnow,alsoneedtoimplementtheminourcode,notjustinsketchesinwhitepapersandpresentations.HowcanwedothatusingJava?

Inthenextchapter(JavaBusinessIntegration),wewillseeexactlywhatJavahastoofferindefiningESBarchitectures.

Chapter2.JavaBusinessIntegrationIntegrationhasbeenanareaforspecialistsforyears,sincenostandardsexistacrossvendorproducts.ThisincreasestheTotalCostofOwnership(TCO)toimplementandmaintainanyintegrationsolution.Eventhoughintegrationisanecessaryevil,CIOsandITmanagerspostponedecisionsandactions,andsometimesgoforad-hocortemporarysolutions.Anysuchactivitywillcomplicatethealreadyconfusedstovepipesanditistheneedofthehourtohavestandardization.Herewearegoingtoinspecttheneedofanotherstandardforbusinessintegration,andalsolookintothedetailsofwhatthisstandardisallabout.

Sowewillcoverthefollowinginthischapter:

Serviceorientedarchitectureinthecontextofintegration

RelationshipbetweenwebservicesandSOA

Serviceorientedintegration

J2EE,JCA,andJBI—howtheyrelate

IntroductiontoJBI

JBINomenclature—maincomponentsinJBI

Provider-consumerrolesinJBI

JBIMessageExchangePatterns(MEP)

SOA—TheMottoInChapter1,wewentthroughintegrationandalsovisitedthemajorintegrationarchitectures.Wehavebeendoingintegrationformanydecadesinproprietaryorad-hocmanner.Today,thebuzzwordisSOAandintheintegrationspace,wearetalkingaboutServiceOrientedIntegration(SOI).LetuslookintotheessentialsofSOAandseewhethertheexistingstandardsandAPIsaresufficientintheintegrationspace.

WhyWeNeedSOAWehavebeenusingmultipletechnologiesfordevelopingapplicationcomponents,andafewofthemarelistedasfollows:

RemoteProcedureCall(RPC)

CommonObjectRequestBrokerArchitecture(CORBA)

DistributedComponentObjectModel(DCOM)

.NETremoting

EnterpriseJavaBeans(EJBs)

JavaRemoteMethodInvocation(RMI)

Onedrawback,whichcanbeseeninalmostallthesetechnologies,istheirinabilitytointeroperate.Inotherwords,ifa.NETremotingcomponenthastosendbytestoaJavaRMIcomponent,thereareworkaroundsthatmaynotworkallthetimes.

Next,alltheabovelistedtechnologiesfollowthebestObjectOrientedPrinciples(OOP),especiallyhidingtheimplementationdetailsbehindinterfaces.Thiswillprovideloosecouplingbetweentheproviderandtheconsumer,whichisveryimportantespeciallyindistributedcomputingenvironments.Nowthequestionis,aretheseinterfacesabstractenough?Torephrasethequestion,canaJavaRMIruntimemakesenseoutofa.NETinterface?

Alongtheselines,wecanpointoutafulllistofdoubtsordeficiencieswhichexistintoday'scomputingenvironment.ThisiswhereSOAbringsnewpromises.

WhatisSOASOAisallaboutasetofarchitecturalpatterns,principles,andbestpracticestoimplementsoftwarecomponentsinsuchawaythatweovercomemuchofthedeficienciesidentifiedintraditionalprogrammingparadigms.SOAspeaksaboutservicesimplementedbasedonabstractinterfaceswhereonlytheabstractinterfaceisexposedtotheoutsideworld.Hencetheconsumersareunawareofanyimplementationdetails.Moreover,theabstractmodelisneutralofanyplatformortechnology.Thismeans,componentsorservicesimplementedinanyplatformortechnologycaninteroperate.WewilllistoutfewmorefeaturesofSOAhere:

Standards-based(WS-*Specifications)

Servicesareautonomousandcoarsegrained

Providersandconsumersarelooselycoupled

Thelistisnotexhaustive,butwehavemanynumberofliteratureavailablespeakingonSOA,soletusnotrepeatithere.InsteadwewillseetheimportanceofSOAintheintegrationcontext.

SOAandWebServicesSOAdoesn'tmandateanyspecificplatform,technology,orevenaspecificmethodofsoftwareengineering,buttimehasproventhatwebserviceisaviabletechnologytoimplementSOA.However,weneedtobecautiousinthatusingwebservicesdoesn'tleadtoSOAbyitself,orimplementit.Rather,sincewebservicesarebasedonindustryacceptedstandardslikeWSDL,SOAP,andXML;itisoneofthebestavailablemeanstoattainSOA.

ProvidersandconsumersagreetoacommoninterfacecalledWebServicesDescriptionLanguage(WSDL)inSOAusingwebservices.DataisexchangednormallythroughHTTPprotocol,inSimpleObjectAccessProtocol(SOAP)format.

WSDLWSDListhelanguageofwebservices,usedtospecifytheservicecontracttobeagreeduponbytheproviderandconsumer.ItisaXMLformattedinformation,mainlyintendedtobemachineprocessable(buthumanreadabletoo,sinceitisXML).Whenwehostawebservice,itisnormaltoretrievetheWSDLfromthewebserviceendpoint.Also,therearemainlytwoapproachesinworkingwithWSDL,whichare

listedasfollows:

StartfromWSDL,createandhostthewebserviceandopentheserviceforclients;toolslikewsdl2javahelpustodothis.

Startfromthetypesalreadyavailable,generatetheWSDLandthencontinue;toolslikejava2wsdlhelpushere.

LetusnowquicklyrunthroughthemainsectionswithinaWSDL.AWSDLstructureisasshownhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitionstargetNamespace=

"http://versionXYZ.ws.servicemix.esb.binildas.com"

…>

<wsdl:types>

<schemaelementFormDefault="qualified"

targetNamespace="http://version20061231.ws.

servicemix.esb.binildas.com"

xmlns="http://www.w3.org/2001/XMLSchema">

</schema>

</wsdl:types>

<wsdl:messagename="helloResponse">

<!--othercodegoeshere-->

</wsdl:message>

<wsdl:portTypename="IHelloWeb">

<!--othercodegoeshere-->

</wsdl:portType>

<wsdl:binding

name="HelloWebService20061231SoapBinding"

type="impl:IHelloWeb">

<!--othercodegoeshere-->

</wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebService20061231SoapBinding"

name="HelloWebService20061231">

<wsdlsoap:address

location="http://localhost:8080/AxisEndToEnd20061231/

services/HelloWebService20061231">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

WewillnowrunthroughthemainsectionsofatypicalWSDL:

types:ThedatatypesexchangedareexpressedhereasanXMLschema.

message:Thissectiondetailsaboutthemessageformats(orthedocuments)exchanged.

portType:ThePortTypecanbelookedatastheabstractinterfacedefinitionfortheexposedservice.

binding:ThePortTypehastobemappedtospecificdataformatsandprotocols,whichwillbedetailedoutinthebindingsection.

port:TheportgivestheURLrepresentationoftheserviceendpoint.

service:Servicecancontainacollectionofportelements.

SinceJBIisbasedonWSDL,wewilldealwithmanyWSDLinstancesinthesubsequentchapters.

SOAPInwebservices,dataistransmittedoverthewireinSOAP.SOAPisanXML-basedmessagingprotocol.SOAPdefinesasetofrulesforstructuringmessagesthatcanbeusedforsimpleone-waymessagingandisusefulforperformingRPC-styleinteractions.EventhoughSOAPisnottiedtoanyparticulartransportprotocol,HTTPisthepopularone.

ASOAP-encodedRPCdialoguecontainsbotharequest

messageandaresponsemessage.LetusconsiderasimpleservicemethodthattakesaStringparameterandreturnsaStringtype:

publicStringhello(Stringparam);

TherespectiveSOAPrequestisshownasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<soapenv:Envelope

xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-

instance">

<soapenv:Body>

<ns1:hello

soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/

encoding/"

xmlns:ns1="http://AxisEndToEnd.axis.apache.

binildas.com">

<in0xsi:type="soapenc:string"

xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/">

Binil

</in0>

</ns1:hello>

</soapenv:Body>

</soapenv:Envelope>

Similartotherequest,theSOAPresponseisshownbelow:

<?xmlversion="1.0"encoding="utf-8"?>

<soapenv:Envelope

xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-

xmlns:xsi="http://www.w3.org/2001/XMLSchema-

instance">

<soapenv:Body>

<ns1:helloResponse

soapenv:encodingStyle="http://schemas.xmlsoap.

org/soap/encoding/"

xmlns:ns1="http://AxisEndToEnd.axis.apache.

binildas.com">

<helloReturnxsi:type="soapenc:string"

xmlns:soapenc="http://schemas.xmlsoap.org/soap/

encoding/">

ReturnFromServer

</helloReturn>

</ns1:helloResponse>

</soapenv:Body>

</soapenv:Envelope>

AsisthecasewithWSDL,wewillbedealingwithmanyinstancesofSOAPrequestsandresponsesinourdiscussionsinthecomingchapters.Hence,letusnotdelveintotheintricaciesofWSDLandSOAP,astherearemanytextbooksdoingthesame.Letuscontinuewithourdiscussiononintegration.

ServiceOrientedIntegration(SOI)InChapter1,weidentifiedESBasanarchitecturalpatterndifferentfromtraditionalintegrationarchitectures,whichsupportstandards-basedservicesforintegration.GartneroriginallyidentifiedESBasthecorecomponentinanSOAlandscape.Gartnersays:

SOAwillbeusedinmorethan80%ofnewmission-criticalapplicationsandbusinessprocessesby2010

Anothermarketstrategystudy,conductedbyGartnerinSOArevealsthat:

TheESBcategorygrewby160%fromyear2004toyear2005

AsistruewithSOA,ESB-basedintegrationhasbeenincreasinglyusingwebservicesstandardsandtechnologiesforservicedescription,hosting,andaccessing.TheadvantageisthatwenotonlyreapallthebenefitsofESBarchitecture(explainedinChapter1),butalsomakesurethattheservicesexposedatthebusarecomplyingwithindustrystandards.ThismeansconsumersandprovidersmakesuseofexistingtoolsetsandframeworkstointeractwiththeESB.MostofthecurrentSOAtoolsetssupportwebservicesandrelatedtechnologies.Thisopensupawholelotofopportunitiesintheintegrationspacetoo,whichleadstoSOI.WhenwevirtualizeservicesintheESB,itisverycriticaltoprovideauniformecosystemforallkindofservices,whetheritiswritteninJava,or.NET,orC++.

Iftheservicesareasperthewebservicestandards,ESBcanprovidethemediationserviceswhichwillhelptointerconnecttheseservices.ExternalizingmediationlogicoutofservicestoanESBwillremovein-codecouplingbetweenservices.Tosumup,ourcurrentSOAinfrastructurestillexistswhichhostsservicesandtakescareofservicemanagementandgovernance.AlsoanESBprovidesSOIintheformofmediation,whichprovidescommunication(alongwithotherfeatures)betweenservices.

JBIinJ2EE—HowtheyRelateTheJava2EnterpriseEdition(J2EE)platformprovidescontainersforclientapplications,webcomponentsbasedonservletsandJavaServerPages(JSP),andEnterpriseJavaBeans(EJB)components.TheseJ2EEcontainersprovidedeploymentandruntimesupportforapplicationcomponents.Theyalsoprovideafederatedviewoftheplatform-levelservices,providedbytheunderlyingapplicationserverfortheapplicationcomponents.Inthissection,wewilllookatwhereJBIispositionedintheJ2EEstack.

Servlets,Portlets,EJB,JCA,andsoonTheworldofJavaisfabulous.Javaspeaksaboutportablecode(.classfiles),portabledata(JAXPandXML),portablecomponents(EJB),andnowportableservices(JAX-WS).However,untillnow,therewasnostandardwaybywhichwecoulddobusiness-levelintegrationacrossapplicationserversfrommultiplevendors.

Businessintegrationcanbedonewithbusinesscomponentsorwithbusinessservices.WeknowthatEJBcomponentscaninteroperateacrossmultiplevendor'sapplicationservers,andsimilaristhecasewithwebservices.WehavebeendoingintegrationwithinourtraditionalJ2EEprogrammingparadigminthepre-ESBera.Thechallengeofaccessing,integrating,andtransformingdatahaslargelybeendonebydevelopers

usingmanualcodingofJ2EEcomponentslikePOJO,EJB,JMS,andJCA.TheseJ2EEAPIsareoptimizedforbusinesspurposeprogramming,andnotforintegration.TheaftereffectisthattheJ2EEprogrammershavetouselow-levelAPIstoimplementintegrationconcerns.

Programmerscreateintegrationcodehavinghardcodeddependenciesbetweenspecificapplicationsanddatasources,whichareneitherefficientnorflexible.Hence,awaytodointegrationinalooselycoupledmannerandtoporttheintegrationsolutionasawholeismissing.Componentsandservicesareonlyapartoftheintegrationsolution.Italsoincludesthestrategytointegrate,thepatternsadaptedtorouteandtransformmessagesandsimilarartifacts.Allthesedifferfordifferentvendor'sproductsandJBIistryingtobringstandardizationacrossthisspace.

JBIandJCA—CompetingorComplementingTheJ2EEConnectorArchitecture(JCA)definesstandardsforconnectingtheJ2EEplatformtoheterogeneousEISsystems.ExamplesofEISsystemsincludeCICS,IMS,TPFsystems,ERP,databasesystems,andlegacyapplicationsnotwrittenintheJavaprogramminglanguage.TheJCAenablestheintegrationofEISswithapplicationserversandenterpriseapplicationsbydefiningadeveloper-levelAPIandavendor-levelSPI.TheSPIsenablesanEISvendortoprovideastandardresourceadapterforitsEIS.Theresourceadapterplugsintoanapplicationserver,thusprovidingconnectivity

betweentheEIS,theapplicationserver,andtheenterpriseapplication.

IfanapplicationservervendorhasextendeditssystemtosupporttheJCA,itisassuredofseamlessconnectivitytomultipleEISs.SofollowingJCA,anEISvendorneedstoprovidejustonestandardresourceadapter,whichhasthecapabilitytoplug-intoanyapplicationserverthatsupportstheJCA.HecannowbeassuredthathisEISwillplugintotheJ2EEcontinuum.

JCA-basedadaptersareusuallyusedtointegratecompliantESBswithEIS.Thismeans,byusingJCA,anEISvendorcanbeassuredthathisEIScanintegratewithcompliantESBs.JCAprovidesthemostefficientwayofresourcepooling,threadpooling,andtransactionhandlingonJMSandotherresourceadapters.Wehavealreadyseenthesimilaritiesbetweenamessagebusandaservicebus.Alongthoselines,wecanunderstandhowimportantistheMOMtechnologysuchasJMS.Hence,theimportanceJCAhasgotinintegration.

WealsoneedtounderstandonesubtledifferencebetweenJBIandJCAhere.JCAisdesignedtosupportthetraditionalrequest-responsemodel,butfailstosupportcomplexlongrunningtransactionsandintegrationscenarios.Muchback-endintegrationdoesnotalwaysfitwellwiththesynchronousrequest-responsemodelandJBIhasgotsomethingelsetoofferhere.JBIisbasedonamediatedmessageexchangepattern.Thatis,whenacomponentsendsamessagetoanothercomponent,themessageexchangeismediatedbytheJBI

infrastructure.Aswewillseeshortly,JBIsupportsmultiplemessageexchangepatterns.Moreover,JBI-basedESBswillgivemorefunctionalitiessuchasservicecomposition,BPM,etc.,whichmakessenseinhandlingback-endintegrationandlongrunningtransactions.

JBI—aNewStandardEveryorganizationwouldliketoleverageexistingITstafftoruntheirintegrationeffortsimilartotheirdailyITdevelopmentandoperations.However,integrationisadifferentartthannormalsoftwaredevelopmentandthatiswhywehaveintegrationarchitects.Thatdoesn'tmeanintegrationexpertshavetobeexpertsinvendorX'sproduct,andarebacktonovice-levelinvendorY'sproduct.Ifthishastohappen,weneedtodosimilaractivitiesacrossmultiplevendor'sproducts.

Aswealreadydiscussed,integrationisnotthatsimpleasitinvolvesintegrationarchitectures,integrationpatterns,andMOMexpertise.Weneedtobuildtheextraintelligentadaptersaroundservicesandendpoints.Theseadaptersaretoworkintandemwiththeplatformprovidertogivelow-levelfeatureslikecommunication,session,state,transport,androuting.Thus,businessintegrationisnotlimitedbyjustapplicationprogramming,butinvolvescomponentsandengineeringprocessesattheapplicationandplatforminterface-level.Hence,tomakeintegrationartifactsportable,eventheintegrationvendors(whodealwithplatformservices)haveabigparttoplay.Thisiswhereweneedstandardizationascomponentsandadaptersshouldbeportableacrossseveral

vendorproducts.

Letmetrytoexplainthispointabitfurther,asthisistheprimeconcernintoday'sintegrationinitiatives.SincetheinceptionofJ2EE,wehavebeenusingmultipleJ2EEcontainersfromdifferentvendors.MostoftheseJ2EEcontainersalsohaveanintegrationstack,whichcanbeeitherpluggedintotheirexistingJ2EEcontainersorcanberunasstandalone.WebsphereBusinessIntegration(WBI)messagebrokerandBEAAqualogicServiceBus(ALSB)arejustafewoftheminthelist.Itistrue,thatmostoftheseintegrationstackstoosupportstandard-basedintegration,followingSOAprinciplesandpatterns.Whatabouttheintegrationartifactsassuch?

WhenIsayintegrationartifacts,Irefertoanyintegrationlibrariesavailable,oranycustomconfigurationthedevelopersdototheabovelibraries,thepackaginganddeploymentartifactstheygenerate.Inotherwords,ifwecreatea.jaror.earfilecontainingsomeintegrationsolutioninALSB;canweportittoWBIlater?Ileavethisquestionopenfortheusercommunityoftheseframeworkstoanswer.So,whathashappenedhere?Asalways,theevolutionofstandardslagsbehindtheevolutionoftechnology.Hence,evenbeforeJBI,wehadmultipleprogrammingparadigmstosolveintegrationissues,butthentheyweretiedtothevendor'senvironment.ThepromiseofJBIistobringportabilityacrossdifferentJBIcontainersfortheintegrationartifacts.

JBIinDetailInChapter1,wediscussedESBarchitecturewhichcanfacilitatethecollaborationbetweenservices.JBIprovidesacollaborationframeworkwhichprovidesstandardinterfacesforintegrationcomponentsandprotocolstopluginto,thusallowingtheassemblyofSOIframeworks.

JSR208JSR208isanextensionofJ2EE,butitisspecificforJBIServiceProviderInterfaces(SPI).SOAandSOIarethetargetsofJBIandhenceitisbuiltaroundWSDL.IntegrationcomponentscanbepluggedintotheJBIenvironmentusingaservicemodelbasedonWSDL.ServicecompositionisamajortargetinESBarchitectureandtheJBIenvironmentaggregatesmultipleservicedefinitionsintheWSDLformintothemessageinfrastructure.

Inthecontextofalargerservicecomposition,wehavemultiplepartners(serviceprovidersorserviceconsumers)andthemetadataforinteractionoftheseindividualpartnersaretermedasthebusinessprotocol.Themetadataofchoreographyplayedbyabusinessprocessinabusinessprotocolistermedastheabstractbusinessprocess.Partnerprocessesinteractwitheachotherbylookingatabstractbusinessprocess;itistheESB'sjobtorealizethisabstractbusinessprocess.JSRaimstomakethisabstractbusinessprocessdefinitionportable.Thismeansthewiringdetailsbetweencomponentsinaservicecompositionscenariocanbe

extractedintoaseparatelayeranditisthislayerwhichwearespeakingaboutJSR208.Thus,JSR208orJBIisafoundationforrealizingSOI.

JSR208mandatesthefollowingforJBIcomponents:

Portable:ComponentsareportableacrossJBIimplementations.

Manageable:Componentscanbemanagedinacentralizedmanner.

Interoperable:Componentsshouldbeabletoprovideservicetoandconsumeservicesfromothercomponents,despitethefactthattheycomefromdifferentsourcesandtransportprotocols.

JBINomenclatureThissectionhelpsustounderstandthemajorcomponentsinJBIarchitectureandtheirroleswithreferencetothefollowingfigure:

Themajorcomponentsareexplainedhere:

JBIenvironment:AJBIenvironmentisasingleJavaVirtualMachine(JVM)wherewecandeployintegrationartifacts.ThisJBIcanbeastandaloneESBoranESBembeddedintheJVMofanapplicationserver.Inthelattercase,evenanEJBcomponentdeployedinanapplicationservercanfunctionasaproviderorconsumertotheESB,thusfurthernarrowingdownthebridgebetweentraditionalJ2EEapplicationserversandtherelativelynewESB.

ServiceEngine(SE):SEsareserviceprovidersorserviceconsumersdeployedlocallywithinaJBIenvironment.Theyprovidetheactualbusinesslogicliketransformation.TransformationservicecanbedonewiththehelpofanXSLTenginebyusingastylesheet.AnotherenginemayuseJCAtogiveadataaccessservice,orBusinessProcessExecutionLanguage(BPEL),orevencustomlogictointegratelegacycodelikethatinCICSormainframe.

BindingComponents(BC):BCprovidecommunicationsprotocolsupportandtheyarenormallyboundtocomponentsdeployedremotelyfromtheJBI

runtime.Infact,nothingpreventsauserfromdefiningabindingforalocalserviceinthecasewhereitcloselyresemblesSE.ThusBCprovidesremoteaccesstoservicesforremoteserviceprovidersandconsumers.

NOTENOTE

ThedistinctionbetweenSEandBCisimportantforvariouspragmaticreasons.Mainly,itseparatesservicelogicfrombindingprotocol.Thisfacilitatesreusability.

JBIContainer:Similartothecontainerinanapplicationserver,aJBIenvironmentbyitselfisaJBIcontainer.ThiscontainerhostsSEandBC.TheinterestingpartisaSEisagainacontainerforenginespecificentitieslikeXSLTengine,stylesheets,rulesengines,andscripts.Thus,aJBIenvironmentisacontainerofcontainerswhereasaserviceengineisacontainerforhostingWSDLdefinedprovidersandconsumerslocaltotheJBI.

Normalizedmessage:Anormalizedmessageconsistsoftwoparts—theactualmessageinXMLformat,andmessagemetadatawhichisalsoreferredtoasthemessagecontextdata.Themessagecontextdatahelpstoassociateextrainformationwithaparticularmessage,asitisprocessedbybothplug-incomponentsandsystemcomponentsinthebus.

Normalizedmessagerouter(NMR):ThenerveoftheJBIarchitectureistheNMR.Thisisabusthroughwhichmessagesflowineitherdirectionfromasourcetoadestination.Thespecialtyofthisrouteristhatmessagesarealwaysinanormalizedformat,irrespectiveofthesourceordestination.NMRthusactsasalightweightmessaginginfrastructurewhichfacilitatesactualmessageexchangeinalooselycoupledfashion.NMRprovidesvaryingQOSfunctionalitiesandthethreelevelsofmessagedeliveryguaranteeprovidedbyNMRarelistedasfollows:

Besteffort:Messagemaybedeliveredonlyonceormorethanonce,oreventhemessagecanbedropped.

AtLeastOnce:Messagehastobedeliveredonceormore,butcannotbedropped.Hence,duplicatescanexist.

Onceandonlyonce:Itisguaranteedthatmessageswillbedeliveredonceandonlyonce.

Pluggablecomponents:ThelooselycoupledfeatureofESBisduetothepluggablearchitectureforservicecomponents.TherearetwobroadcategoriesofpluggablecomponentscalledSEandBC.Pluggablecomponentscanplaytheroleofserviceprovider,serviceconsumer,orboth.PluggablecomponentsareconnectedtotheNMRthroughaDeliveryChannel.

Serviceprovidersandserviceconsumers:TherearemainlytworolesplayedbypluggablecomponentswithinanESB,theserviceproviderandserviceconsumer.Componentscanactasbothaproviderandaconsumeratthesametime.ServicedefinitionisavailableintheformofWSDLandthisistheonlysharedartifactbetweenprovidersandconsumers.SinceendpointinformationisnotsharedbetweenprovidersandconsumersintheESB,looselycoupledintegrationisfacilitated.

Itistobenotedthatasingleservicedefinitionmaybeimplementedbymultipleproviders.Similarly,aconsumer'sservicedefinitionofinterestmightbeprovidedbymultipleproviderstoo,inESBarchitecture.Moreover,theroleofbothproviderandconsumercanbeplayedbythecomponenteitherdirectlyorthroughaproxyforaremoteservice.

DeliveryChannel(DC):DCconnectsamessagesourceandadestination.ThemessaginginfrastructureortheNMRisthebusformessageexchangeformultipleserviceprovidersandconsumers.Hencewhenaserviceproviderhasgotinformationtocommunicate,itdoesn'tjustflingthemessageintotheNMR,butaddsthemessagetoaparticularDC.Similarly,amessageconsumerdoesn'tjustpickitupatrandomfromthemessagingsystem.Instead,theconsumerreceivesthemessagefromaparticularDC.ThusDCsarelogicaladdressesintheESB.

Provider—ConsumerContractIntheJBIenvironment,theproviderandconsumeralwaysinteractbasedonaservicesmodel.Aserviceinterfaceisthecommonaspectbetweenthem.WSDL1.1and2.0areusedtodefinethecontractthroughtheservicesinterface.

ThefollowingfigurerepresentsthetwopartsoftheWSDL

representationofaservice:

IntheAbstractModel,WSDLdescribesthepropagationofamessagethroughatypesystem.AmessagehassequenceandcardinalityspecifiedbyitsMessageExchangePattern(MEP).AMessagecanbeaFaultMessagealso.AnMEPisassociatedwithoneormoremessagesusinganOperation.AnInterfacecancontainasingleOperationoragroupofOperationsrepresentedinanabstractfashion—independentofwireformatsandtransportprotocols.

AnInterfaceintheAbstractModelisboundtoaspecificwireformatandtransportprotocolviaBinding.ABindingisassociatedwithanetworkaddressinanEndpointandasingleServiceintheconcretemodelaggregatesmultipleEndpointsimplementingcommoninterfaces.

DetachedMessageExchange

JBI-basedmessageexchangeoccursbetweenaProviderandConsumerinadetachedfashion.Thismeans,theProviderandConsumerneverinteractdirectly.Intechnicalterms,theyneversharethesamethreadcontextofexecution.Instead,theProviderandConsumeruseJBINMRasanintermediary.Thus,theConsumersendsarequestmessagetotheNMR.TheNMR,usingintelligentroutersdecidesthebestmatchedserviceprovideranddispatchesthemessageonbehalfoftheConsumer.TheProvidercomponentcanbeadifferentcomponentorthesamecomponentastheConsumeritself.TheProvidercanbeanSEoraBCandbasedonthetypeitwillexecutethebusinessprocessbyitselfordelegatetheactualprocessingtotheremotelyboundcomponent.TheresponsemessageissentbacktotheNMRbytheProvider,andtheNMRinturnpassesitbacktotheConsumer.Thiscompletesthemessageexchange.

ThefollowingfigurerepresentstheJBI-basedmessageexchange:

Therearemultiplepatternsbywhichmessagesareexchanged,whichwewillreviewshortly.

Provider—ConsumerRoleThoughaJBIcomponentcanfunctionasaConsumer,aProvider,orasbothaConsumerandProvider,thereisclearcutdistinctionbetweentheProviderandConsumerroles.Theserolesmaybeperformedbybindingsorengines,inanycombinationofthetwo.WhenabindingactsasaserviceProvider,anexternalserviceisimplied.Similarly,whenthebindingactsasaserviceConsumer,anexternalConsumerisimplied.Inthesameway,theuseofaServiceEnginesineitherroleimpliesalocalactorforthatrole.

Thisisshowninthefollowingfigure:

TheProviderandConsumerinteractwitheachotherthroughtheNMR.Whentheyinteract,theyperformthedistinctresponsibilities(notnecessarilyinthesameorder).

Thefollowingisthelistofresponsibilities,performedbytheProviderandConsumerwhileinteractingwithNMR:

1. Provider:Oncedeployed,theJBIactivatestheserviceproviderendpoint.

2. Provider:ProviderthenpublishestheservicedescriptioninWSDLformat.

3. Consumer:Consumerthendiscoverstherequiredservice.Thiscanhappenatdesigntime(staticbinding)orruntime(dynamicbinding).

4. Consumer:Invokesthequeriedservice.

5. ProviderandConsumer:SendandrespondtomessageexchangesaccordingtotheMEP,andstateofthemessageexchangeinstance.

6. Provider:Providestheservicebyrespondingtothefunctioninvocations.

7. ProviderandConsumer:Respondswithstatus(faultordone)tocompletethemessageexchange.

Duringruntimeactivation,aserviceprovideractivatestheactualservicesitprovides,makingthemknowntotheNMR.Itcannowrouteserviceinvocationstothatservice.

javax.jbi.component.ComponentContextcontext;

//Initializedvia.AOP

javax.jbi.messaging.DeliveryChannelchannel=

context.getDeliveryChannel();

javax.jbi.servicedesc.ServiceEndpoint

serviceEndpoint=null;

if(service!=null&&endpoint!=null)

{

serviceEndpoint=context.activateEndpoint

(service,endpoint);

}

TheProvidercreatesaWSDLdescribedserviceavailablethroughanendpoint.AsdescribedintheProvider-Consumercontract,theserviceimplementsaWSDL-basedinterface,whichisacollectionofoperations.Theconsumercreatesamessageexchangetosendamessagetoinvokeaparticularservice.Sinceconsumersandprovidersonlysharetheabstractservicedefinition,theyaredecoupledfromeachother.Moreover,severalservicescanimplementthesameWSDLinterface.Hence,ifaconsumersendsamessageforaparticularinterface,theJBImightfindmorethanoneendpointconformingtotheinterfaceandcanthusroutetothebest-fitendpoint.

MessageExchangeAmessageexchangeisthe"MessagePacket"transferred

betweenaconsumerandaproviderinaserviceinvocation.Itrepresentsacontainerfornormalizedmessageswhicharedescribedbyanexchangepattern.Thusmessageexchangeencapsulatesthefollowing:

Normalizedmessage

Messageexchangemetadata

Messageexchangestate

Thus,messageexchangeistheJBIlocalportionofaserviceinvocation.

ServiceInvocationAnend-to-endinteractionbetweenaserviceconsumerandaserviceproviderisaserviceinvocation.Serviceconsumersemployoneormoreserviceinvocationpatterns.ServiceinvocationthroughaJBIinfrastructureisbasedona'pull'model,whereacomponentacceptsmessageexchangeinstanceswhenitisready.Thus,onceamessageexchangeinstanceiscreated,itissentbackandforthbetweenthetwoparticipatingcomponents,andthiscontinuestillthestatusofthemessageexchangeinstanceiseithersetto'done'or'error',andsentonelasttimebetweenthetwocomponents.

MessageExchangePatterns(MEP)

Serviceconsumersinteractwithserviceprovidersformessageexchangeemployingoneormoreserviceinvocationpatterns.TheMEPdefinesthenames,sequence,andcardinalityofmessagesinanexchange.Therearemanyserviceinvocationpatterns,and,fromaJBIperspective,anyJBI-compliantESBimplementationmustsupportthefollowingfourserviceinvocations:

One-Way:Serviceconsumerissuesarequesttotheserviceprovider.Noerror(fault)pathisprovided.

ReliableOne-Way:Serviceconsumerissuesarequesttotheserviceprovider.Providermayrespondwithafaultifitfailstoprocesstherequest.

Request-Response:ServiceConsumerissuesarequesttotheserviceprovider,withexpectationofresponse.Providermayrespondwithafaultifitfailstoprocessrequest.

RequestOptional-Response:Serviceconsumerissuesarequesttotheserviceprovider,whichmayresultinaresponse.Bothconsumerandproviderhavetheoptionofgeneratingafaultinresponsetoamessagereceivedduringtheinteraction.

TheaboveserviceinvocationscanbemappedtofourdifferentMEPsthatarelistedasfollows.

In-OnlyMEPIn-OnlyMEPisusedforone-wayexchanges.ThefollowingfigurediagrammaticallyexplainstheIn-OnlyMEP:

IntheIn-OnlyMEPnormalscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswiththestatustocompletethemessageexchange.

IntheIn-OnlyMEPnormalscenario,sincetheConsumerissuesarequesttotheProviderwithnoerror(fault)path,anyerrorsattheProvider-levelwillnotbepropagatedtotheConsumer.

RobustIn-OnlyMEPRobustIn-OnlyMEPisusedforreliable,one-waymessageexchanges.Ithasgottwousagescenarios—thenormalscenarioandthefaultscenario.

Normalscenario:IntheRobustIn-OnlyMEPinthenormal(withoutanyfault)scenario,thesequenceofmessageexchangesissimilartothatofIn-OnlyMEP.Thedifferencecomestoplayonlyinthecasewherethereisan

errorattheProvider-level,whichwillbedescribedasthenextitem.

ThefollowingfigureexplainstheRobustIn-OnlyMEP—Normalscenario:

IntheRobustIn-OnlyMEP—Normalscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswiththestatustocompletethemessageexchange.

Faultscenario:IntheRobustIn-OnlyMEPinthefaultscenario,theConsumerissuesarequesttotheProviderandtheProviderwillrespondwithafaultinsteadofthenormalresponse.

ThefollowingfigureexplainstheRobustIn-OnlyMEP—Faultscenario:

IntheRobustIn-OnlyMEP—Faultscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswithafault.

ServiceConsumerrespondswiththestatustocompletethemessageexchange.

So,whatyouneedtonoteisthat,intheRobustIn-OnlyMEP—Normalscenario,theexchangeisterminatedwhentheProviderrespondswithstatustocompletethemessageexchange,whereasintheRobustIn-OnlyMEP—Faultscenario,theexchangeisterminatedwhentheConsumerrespondswiththestatustocompletethemessageexchange.Thestatustocompletethemessageexchangeeveninthecaseoffaultscenario,bringsrobustnesstoit.

In-OutMEPIn-OutMEPisusedforarequest-responsepairofservice

invocations.HeretheConsumerissuesarequesttotheProvider,withexpectationofaresponse.Ithasgottwousagescenarios—thenormalscenarioandthefaultscenario.

Normalscenario:IntheIn-OutMEPinthenormal(withoutanyfault)scenario,theConsumerissuesarequesttotheProvider,withexpectationofaresponse.TheProviderrespondswiththenormalresponse.

ThefollowingfigureexplainstheIn-OutMEP—Normalscenario:

IntheIn-OutMEP—Normalscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswithamessage.

ServiceConsumerrespondswiththestatustocompletethemessageexchange.

Faultscenario:IntheIn-OutMEPinthefaultscenario,theConsumerissuesarequesttotheProviderwithexpectationofaresponseandtheProviderwillrespondwithafaultinsteadofthenormalresponse.

ThefollowingfigureexplainstheIn-OutMEP—Faultscenario:

IntheIn-OutMEP—Faultscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswithafault.

ServiceConsumerrespondswiththestatustocompletethemessageexchange.

In-Optional-OutMEPIntheIn-Optional-OutMEP,theserviceConsumerissuesarequesttotheserviceProvider,whichmayormaynotresultinaresponse.BoththeConsumerandtheProviderhavetheoptionofgeneratingafaultinresponsetoamessagereceivedduringtheinteraction.

One-Way:IntheIn-Optional-OutMEP—One-Wayscenario,theserviceConsumerissuesarequesttotheserviceProvider.TheProviderneitherreturnsanyresponse,norgeneratesanyfault.

ThefollowingfigureexplainstheIn-Optional-OutMEP—One-Wayscenario:

IntheIn-Optional-OutMEP—One-Wayscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswiththestatustocompletethemessageexchange.

Two-Way:IntheIn-Optional-OutMEP—Two-Wayscenario,theserviceConsumerissuesarequesttotheserviceProvider.TheProviderthenreturnsaresponse.

ThefollowingfigureexplainstheIn-Optional-OutMEP—Two-Wayscenario:

IntheIn-Optional-OutMEP—Two-Wayscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswithamessage.

ServiceConsumerrespondswiththestatustocompletethemessageexchange.

Provider-Fault:IntheIn-Optional-OutMEP—Provider-Faultscenario,theserviceConsumerissuesarequesttotheserviceProvider.TheProvidergeneratesafaultinsteadofthenormalresponse.

ThefollowingfigureexplainstheIn-Optional-OutMEP—Provider-Faultscenario:

IntheIn-Optional-OutMEP—Provider-Faultscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswithafault.

ServiceConsumerrespondswiththestatustocompletethemessageexchange.

Consumer-Fault:IntheIn-Optional-OutMEP—Consumer-Faultscenario,theserviceConsumerissuesarequesttotheserviceProvider.TheProviderthenreturnsaresponse.TheConsumergeneratesafaultwhileacceptingtheresponse.

ThefollowingfigureexplainstheIn-Optional-OutMEP—Consumer-Faultscenario:

IntheIn-Optional-OutMEP—Consumer-Faultscenario,thesequenceofoperationsisasfollows:

ServiceConsumerinitiateswithamessage.

ServiceProviderrespondswithamessage.

ServiceConsumerrespondswithafault.

ServiceProviderrespondswiththestatustocompletethemessageexchange.

WhereconsideringaMEP,wealwaysconsidertheserviceprovider'spointofview.Thus,amessagetargetedtowardstheproviderinanIn-OnlyMEPisthe'In'partoftheMEP.Onthecontrary,ifamessageistargetedtowardstheconsumer,itisinfacttargetedoutfromtheprovider,andhenceisthe'Out'partoftheMEP.

Thus,dependingupontheroleofthecomponentinthemessageexchange,theappropriatepartormessageiscreated,initialized,andsenttothedeliverychannel.ForanIn-Outscenario,thetypicalstepsareasfollows:

javax.jbi.messaging.InOutinout=

createInOutExchange(new

QName(addressNamespaceURI,addressLocalPart),

null,null);

inout.setProperty("correlationId",id);

//setotherproperties

javax.jbi.messaging.NormalizedMessagenMsg=

inout.createMessage();

//

nMsg.setProperty(Constants.PROPERTY_SSN_NUMBER,

ssnNumber);

//setotherproperties

inout.setInMessage(nMsg);

send(inout);

ESB—WillitSolveallOurPainPointsInChapter1,weintroducedESBandalsolookedintowhatJBIhasgottoofferhere.IfyouarefamiliarwithSOAprinciples,onesubtlefact,whichisevidentnowisthatESBorJBIarenotanendbythemselves,butameanstowardsanend(whichisSOA).AnESBisnotrequiredtobuildanSOA,norisJBIrequiredforESBorSOA.However,allofthemhavesomethingincommonusingJBI—wecanbuildstandardcomponentstobedeployedintoESBarchitectures.Thus,JBIbyitselfisoneofthewaysbywhichwecanattainSOA.Thereisalsoacaveattothis—justfollowingJBIorESBwillnotguaranteethatyouattainSOA.Increasingly,youwillhearrequestsfromyourprojectstakeholderstoimplementanESBwithoutconsideringSOAasawhole,suchthattheywant

immediatesolutions.ItistechnicallyfeasibletobuildESB,whichactaspipesinterconnectingsystems,butthesuccessofsuchESBarchitectureswithoutconsideringtheSOAlandscape,whichitissupposedtobeapartof,willbedifficulttomeasure.

SummaryJBIisthenewintegrationAPIintroducedintheJ2EEworld.ItisagreatenablerforSOAbecauseitdefinesESBarchitecture,whichcanfacilitatethecollaborationbetweenservices.Itprovidesforlooselycoupledintegrationbyseparatingouttheprovidersandconsumerstomediatethroughthebus.

TheNMRprovidesacommonintegrationchannelthroughwhichthemessagesflow.ServicesarepublishedinthebususingtheWSDLstandard.Providersandconsumersarethedifferentrolestakenbytheintegrationcomponentswithrespecttothebus,whenpluggedintotheJBIbus.MessageexchangetakesplacethroughdifferentMEPs,eachprovidingdifferentlevelsofreliability.

ThenextchapterwillintroduceaJBIcontainer.Bereadytowetyourhandswithsomecodetoo—tobuildanddeployyourfirstJBIsample.

Chapter3.JBIContainer—ServiceMixThefirsttwochaptersintroducedESBandJBIrespectively,withmuchtheoryandlessofcode.Justlikeme,youtoomighthavecomeacrossalotofwhitepapersandpointofviewsontheabovetwotechnologies.However,whenwewanttoactuallyimplementthemintoourtechnicalarchitectures,weneedworkingcodedemonstratingboth.

JustlikeanyotherJavaAPIs,servletorEJB,foraJBIAPItoo,weneedconcreteimplementation.TherearemanyimplementationssupportingESBarchitecturesavailableinthemarkettoday.AcoupleofthemcaninteroperatewiththeJBIAPIwhereasafewotherstackleJBIonthesideofquiteadifferentprogrammingmodel.ServiceMixisanopen-sourceESBplatforminJavaprogramminglanguage,builtfromthegroundupwithJBIAPIsandprinciples.

Duetothereasonquotedinthefirstparagraph,wewilluseServiceMixtobetterunderstandJBIandESB.Hence,mostofthesubsequentchaptersinthisbookwillintroducenewscenariosorpatternsinbusinessintegrationandthentrytosolvethemintheJBIwaywithcodesamplesinServiceMix.Whatyouneedtokeepinmindisthateachoftheseintegrationtechniquescanbeusedasstandalone,orinintegrationwithotherscenariosandpatternstobringoutan

integrationsolutionusingESBarchitecturalblueprints.

Wewillcoverthefollowinginthischapter:

IntroductiontoServiceMix—theJBIcontainer

FewotherESBproductsavailableinthemarket

WheretodownloadandhowtoinstallServiceMix

FirstJBIsample

ServiceMix—UndertheHoodServiceMixisbasedonSOAandEventDrivenArchitecture(EDA),andhenceprovidesaplatformforSOI.LetuslookmoreintothisJBIcontainer.

SalientFeaturesServiceMixisbuiltbasedontheJBI(JSR208)specificationandhencecomponentsareportableacrossESBcontainers.ServiceMixislightweightandcanberunstandaloneorembeddedinothercontainers.SinceitisJBI-compliant,ServiceMixcanitselfbepluggedintoanotherJBI-compliantESB.ServiceMixhasintegratedSpringsupport,andhencewecanintegrateandwireservicesandcomponentsinSpring-likeconfigurationfiles.TheJBIstandardspeaksaboutstandarddeploymentunitformatsintheformofserviceunitandserviceassembly.ThismeanswecanhotdeployanyJBI-compliantBPELengine(orsetofBPELfilesintoaBPELengine),ruleengine,transformationengine,routingengine

(eventhoughServiceMixdoesitsownrouting),scriptingengine,orotherintegrationcomponent(suchasspecificJBIbindingcomponents)directlyintoServiceMix.

ServiceMixArchitectureJBIisaspecificationandvendorsarefreetoimplementtheJBIcontainerintheirownways,justliketherearemultipleEJBcontainersbroughtoutbymultiplevendors.Eachvendor'scontainerhastorespecttheJBIAPIsifitistobeJ2EE-compliant.ServiceMixisaJBIcontainerandhenceiscompliantwiththeJBIAPIs,buthasgotitsownfeaturesandwayofroutingmessages.LetuslookmoreintotheinternalarchitectureofServiceMix.

ArchitectureDiagramJBIcompliancyisthemainfeatureoftheServiceMixarchitecture.Thismeans,asshowninthefollowingarchitecturediagram,ServiceMixisanopenarchitecture.So,anyJBI-compliantcomponentcanfitintothearchitecture.Moreover,thearchitectureisalsoscalablefromadeploymentperspective.Mosthub-and-spokearchitecturesuffersfromthesinglepointoffailure.However,ServiceMix,duetotheopennature,canalsocollaboratewithanyotherESB,effectivelypluggingitsroutingcapabilitiesintootherESBcores,thusgeneratingafederationofservicecontainers.

NormalizedMessageRouterFlowsComponentspluggedintoServiceMix,whethertheyarelocalorremotetoit,interactwitheachotherthroughtheNMR.Moreover,ServiceMixisbasedonMOMprinciples.Hence,messagesareexchangedbetweencomponentsthroughtheNMRusingasuitableMEP.Toexchangemessages,differentmessagedispatchpoliciescanbeadoptedwhichwilldecidetheQOSofthemessageexchanges.EachofthesepoliciesisabstractedoutasdifferentNMRflowsinServiceMix.DependinguponthespecificusecaseyouwanttoimplementusingServiceMix,theactualNMRflowcanbespecified.ItisalsotobenotedthatdifferentNMRflowswillexhibitdifferentcapabilitiesintermsofcrosscuttingconcernssuchasmessagebrokeringandmessagebuffering.

ServiceMix,atpresent,providesfourNMRflowtypes:

Straightthrough(ST)flow:STPisanalogoustotheB2Btradingprocess

forcapitalmarketsandpaymenttransactionsdoneelectronically.thisisdonewithoutneedingtorekeyormanuallyintervenetheSTPflow.AmessageexchangeisroutedSTfromthesourcetothedestination.Thereisnostagingorbufferingofmessagesenroute.ThiskindofflowispreferredforcaseswheretheServiceMixcontainerisdeployedwithsimpleflows(nostate)orisembedded.Sincethereisnostagingorbuffering,latencywillbeaslowaspossible.

ThefollowingfigurerepresentsaSTflow:

StagedEventDrivenArchitecture(SEDA)flow:SEDAdecomposesaserviceintomultiplestages,whereeachstageisanevent-drivenservicecomponentthatperformssomeaspectofprocessingtherequest.Eachstagecontainsasmall,dynamicallysizedthreadpooltodriveitsexecution.SEDAprovidesnonblockingI/Oprimitivestoeliminatethemostcommonsourcesoflongblockingoperations.

IntheServiceMixSEDAflow,wehaveasimpleeventstagingbetweentheinternalprocessesintheNMRbroker.SEDAisthedefaultflowinServiceMixandissuitedforgeneraldeployment,astheadditionalstagingcanbufferexchangesbetweenheavilyroutedtocomponents(wherestatemaybeused),forexample.

ThefollowingfigurerepresentsaSEDAflow:

JavaMessageService(JMS)flow:IntheServiceMixJMSflow,wecanleveragethetestedandprovenmethodologyofMOMtoaddressscalabilityorfailover.UsingJMSflow,multipleServiceMixcontainerscancollaborateinaclusterorotherwise,toprovidecomponentandservicereplication.WhenwedeployacomponenteitherasaPOJOorasanarchivecomponentintoaJMSflowconfiguredServiceMixcontainer,allthecontainersintheclusterarenotifiedofthedeployment.TheJMSNMRflowcanhandleautomaticrouting(andfailover)ofmessageexchange(s)betweenmultiplecontainerinstances.

ThefollowingfigurerepresentsaJMSflow:

JCAFlow:TheServiceMixJCANMRflowisverymuchsimilartotheJMSflow.Infact,ServiceMixusesJMSsessionsastheunderlyingmechanismsothatmultipleServiceMixcontainerscancollaborateinacluster.Inaddition,JCAprovidessupportforXAtransactionswhensendingandreceivingJBIexchanges.

ThefollowingfigurerepresentsaJCAflow:

OtherESBsTherearequiteafewESBframeworksavailableintheindustrytodayandwewilllistafewofthemhereforcompletenessofourdiscussion.

MuleMuleisdefinedasalightweightmessagingframeworkfunctioningasanESB.ThisESBfeaturesadistributedobjectbroker,whichcanhandleinteractionsbetweendifferentsystems,applications,components,andservices,irrespectiveofthetransportprotocolsandbindingtechnologies.MuleprovidesaUniversalMessageObject(UMO)API(insideorg.mule.umopackage),awayforcomponentstointeractwithoutneedingtoknowabouttheprotocolordeliverymechanismsofinformationpassedbetweenthem.

MulecanhoststandardPOJOs,whichcanbemanagedfromcontainerssuchasSpring,Pico,andPlexusorfromtheclasspath,oranyothersource.MulehasaJBIinterfacewhichwillcomplimentandnotcompetewithServiceMix.MuleandJBIfunctionsdifferentlyinthewaytheyexchangemessageformats.

JBIisXMLandWSDLcentricwhereasMulemakesnoassumptionsaboutthemessagetype,sothatyoucaneasilyuseStrings,binaries,MIME,XML,objects,streams,oramixturewithoutanyextradevelopment.TostreamallMulesupportedformatsthroughaJBI-compliantcontainer,suitabletunnelingmayneedtobedoneorbinarylikemessagesneedtobetransformedintoXMLformat.Thus,JBIbringsWSDLcentricstandardization,whereasMuleprovidesmoreoptionsintermsofflexibility.

Celtix

CeltixisanESBwhichisJBI-compliant.LeveragingCeltix,developerscanbuildserviceenginesandbindingcomponents.SinceCeltixisJBI-compliant,theserviceenginesandbindingcomponentstooareJBI-compliant,hencecanbedeployedintoanotherthird-partyJBIcontainer.Similarly,CeltixisalsoafullfledgedJBI-compliantcontainer.Thismeansanythird-partyJBI-compliantserviceenginesandbindingcomponentscanbedeployedintoaCeltixESBcontainer.

EventhoughCeltixisJBI-compliant,JBIobjectivesareslightlydifferentfromthatofCeltix.Themaindifferencesarelistedasfollows:

AJBI-compliantserviceengineorbindingcomponentisessentiallyablackboxandthereislittleornocontroloverthemessageflowwithinthem.

ThenormalizedmessageformatspecifiedbyJBIisXMLandhenceexchangeofnonXML-basedmessageformats,likethatofCORBA,willbedifficultandattheveryleastwillrequirethebinaryformattedmessagestobetransformedintoanXMLformat.

Forbindingcomponentsandserviceenginesintheroleofprovider,WSDListhecontractinJBI.WSDLmaynotbeappropriateinallscenarios.Forexample,inthecaseoflegacyintegrationinvolvingproprietaryAPIcalls.

ObjectreferencesandcallbacksarenotspecifiedinJBI.

Celtix,beingJBI-compliant,isalsotryingtobridgetheabovementionedgaps,whichareyettobeprovenasgapsbyindustrybasedonrealintegrationscenarios.

IonaArtixArtixESBserviceenablesintegrationexistingserversdirectly

attheendpointswithouttheneedforaseparateintegrationserver,thusfacilitatingmacro-levelintegration.ArtixisaplatformindependentinfrastructureproductforbuildingJava,C/C++,andmainframewebservices.Allfeaturescanbeconfigureddynamicallyprovidingmaximumflexibilityforimplementingascalable,fullydistributedSOA.ArtixESBprovidedtoolsincludeArtixDesigner,Codegenerators,andManagementConsoletomakecreating,testing,anddeployingserviceseasy.TheArtixESBcontainerisaserverthatallowsyoutorunserviceplug-ins,eitherthosethatcomewithArtixESBorcustomcomponents,andprovidesthreading,resourcemanagement,andnetworkmanagementservices.However,Artixtechnicalspecificationdoesn'tspeakaboutJBI,nordotheyclaimthatArtixcomponentsinteroperatewithotherJBIcontainers.

PEtALSPEtALSisanopen-sourceJBIplatform.PEtALSisbasedonJSR-208andprovideslightweightandpackagedintegrationsolutions,byprovidingasolidbackboneforyourenterpriseinformationsystem.PEtALSisbasedonESBfordataexchange.PEtALShasastrongfocusondistributionandclusteringbybasingitsmessageexchangemiddlewareonJORAM(anopen-sourceJMSimplementation).

ChainBuilderChainBuilderisJBI-compliantwiththeadvantagethatithides

thecomplexitiesofJBIbehindaGUI.TheseGUIcapabilitiesandconfigurationeditorsenablesthepoint-and-clickmappingofnon-XMLformattedmessagessuchasvariable,fixed,andX12EDIformats.TheGUIhasanEclipse-basedplug-in,whichwillenabledrag-and-dropfunctionalityforESBcomponentsthroughwizards.

InstallingServiceMixIagreethatweneedtostartdoing,ratherthanreading.ThissectionisintendedtohelpthereadergetstartedwithServiceMix.Wewilltryoutfewexampleswithoutlookingmuchintotherationalebehinddoingso,sincethesamehasbeencoveredthroughotherchapters.Moreover,asingle"GettingStarted"sectionaloneisnotsufficienttohelpareadernewtoESBtoappreciateallaspectsofit;hence,wewillnotattemptthatinthischapteralone.

Therearemultiplewaystogetstartedbutobviouslydeveloperslikeushavetocodesomething,build,deploy,andgetthatrunningwithouttoomuchhassle.Thatisexactlywhatwewilldointhissection.Let'sdothatnow.

HardwareRequirementsAsofServiceMix3.0.x,weneedthefollowingminimumhardware:

31MBoffreediskspacefortheServiceMix3.0.xbinarydistribution

OSRequirementsThefollowingflavorsofServiceMixinstallsareavailable:

Windows:WindowsXPSP2,Windows2000

Unix:UbuntuLinux,PowerdogLinux,MacOS,AIX,HP-UX,Solaris,oranyUnixplatformthatsupportsJava

Run-timeEnvironmentServiceMixrequirethefollowingrun-timeenvironmentsettings:

JavaDeveloperKit(JDK)1.6.x(http://java.sun.com/javase/downloads/index.jsp).

TheJAVA_HOMEenvironmentvariablemustbesettotheparentdirectorywheretheJDKisinstalled.

Forexample,C:\Yourfilepath\jdk.1.6.0_04.

ApacheAntand/orMaven.

InstallingServiceMixinWindowsThestepsforinstallingServiceMixinWindowsarelistedasfollows:

ClicktheServiceMix3.1.1ReleaselinkundertheLatestReleasessectionofthedownloadpageavailableathttp://incubator.apache.org/servicemix/download.html.

Downloadthebinarydistributionofyourchoice.Forexample,apache-servicemix-3.1.x.zip;apache-servicemix-3.1.1-

incubatingisthepreferredrelease.

ExtractthisZIPfileintoadirectoryofyourchoice.Itisadvisednottohaveillegalcharactersorblankspacesintheinstallationpathdirectories.

NOTENOTE

Asofthiswriting,apache-servicemix-3.1.1-incubatingisthestablerelease.YoucandownloadthisversionoftheServiceMixbinaryfrom:http://incubator.apache.org/servicemix/servicemix-311.html

InstallingServiceMixinUnixToinstallServiceMixinUnix,followsimilarproceduresasforWindows,exceptdownloadthebinarydistributionwithfilenamesimilartoapache-servicemix-x.x.x.tar.gz.

ConfiguringServiceMixIntheServiceMixinstallationhomedirectory,thereisasub-directorynamedconf.ThishostsallmajorconfigurationfilesforServiceMix.servicemix.propertiesherecontainstheportspecifications,especiallythermi.port.Youcanchangesomethinghere,ifthedefaultportsareengagedorforsomeotherreason.

StartingServiceMixTostartServiceMix,gotoSERVICEMIX_HOME\bin(whereSERVICEMIX_HOMEistheparentdirectorywhereyouhaveextractedthebinaryZIP)andthenexecuteservicemix.bat.Now,ServiceMixisrunningwithabasicconfiguration,butnocomponents.

WhilestartingServiceMix,workingdirectoriesgetcreated

relativetothecurrentdirectoryfromwhereyouarestartingServiceMix.

StoppingServiceMixForbothWindowsandUnixinstallations,youcanterminateServiceMixbytypingCTRL-CinthecommandshellorconsoleinwhichServiceMixisstarted.

ResolvingclasspathIssuesWhenweexpandthebinaryZIPfolderofServiceMixinstallation,alltherequiredlibrariesarenotextractedandincludedinthecorrectfolder.InServiceMix,therequiredJavalibrariesshouldbeplacedinSERVICEMIX_HOME\liborSERVICEMIX_HOME\lib\optionalfolder.Soanymissinglibrariescanbeaddedtothesetwofolders.SomelibrariesarealreadyavailableinSERVICEMIX_HOME\componentsorSERVICEMIX_HOME\components\libfolder,andwecanextractthelibrariesfromtheseplacestoSERVICEMIX_HOME\liborSERVICEMIX_HOME\lib\optionalfoldersasandwhenrequired.

ThefollowingarethetwomostcommonerrorsthathappenwhenstartingServiceMixandtherequiredlibrariesarenotfoundinthecorrectplace:

Causedby:java.lang.ClassNotFoundException:…

Causedby:

org.springframework.beans.factory.BeanDefinitionSto

reException:Unrecognizedxbeannamespacemapping:…

Itisveryimportantthatwheneitheroftheaboveerrorsorsomesimilar"librariesnotfound"errorhappens,youeitherfollowwhatwehavealreadyexplainedordownloadanydependentlibrary(.jarfiles)fromthird-partywebsites,andplacethemintheSERVICEMIX_HOME\liborSERVICEMIX_HOME\lib\optionalfolder.

ServiceMixComponents—aSynopsisAsisshownintheServiceMixarchitecturediagram,ServiceMixshipsstandardJBIcomponentsandlightweightJBIcomponents.

StandardJBIComponentsServiceMixstandardJBIcomponentsarefullyJBI-compliant,andsupporttheJBIpackaginganddeploymentmodel.Theyareplacedinthefolder%SERVICEMIX_HOME%\components,andthemajorcomponentsarelistedasfollows:

servicemix-bean:FormappingPOJObeanstoJBIexchanges.

servicemix-bpe:BPELenginebasedonaSybasedonationtotheApacheODEproject.

servicemix-camel:CamelprovidesafullsetofEnterpriseIntegrationPatternsbothfromJavacodeandSpringXML.

servicemix-drools:ProvidesintegrationwithDroolsrulesengine.

servicemix-eip:ProvidesEnterpriseIntegrationPatterns.

servicemix-file:ThisbindingcomponentprovidesintegrationwiththeFilesystem.

servicemix-ftp:AnFTPbindingcomponent.

servicemix-http:AHTTPbindingcomponent.

servicemix-jms:ProvidesintegrationwithmessagingmiddlewarethroughJMS.

servicemix-jsr181:ServiceEnginetoexposeannotatedPOJOsasservices.

servicemix-lwcontainer:Thiscomponentisacontainertowhichwecandeploylightweightcomponents.

servicemix-quartz:ServiceEngineusedtoscheduleandtriggerjobsusingtheQuartzscheduler.

servicemix-saxon:ServiceEngineforintegratingXSLT/XQueryengines.

servicemix-script:HelpstointegratescriptingengineswithJBI.

servicemix-wsn2005:ServiceEngineimplementingOasisWS-Notificationspecification.

servicemix-xmpp:HelpstocommunicatewithXMPP(Jabber)serversthroughtheJBIbus.

LightweightJBIComponentsServiceMixlightweightcomponentsarenotpackagedanddeployedasperJBIspecification.ThisisbecausethecomponentsusedherearelightweightcomponentsthatactivateasingleJBIendpointandtheydonotsupportJBI

deployments.Instead,theycanbeconfiguredusingtheSpringconfiguration.

Listedasfollowsarethemajorlightweightcomponents:

Cache:Cachecomponentcancacheserviceinvocationstoavoidunnecessaryload.

Componenthelperclasses:ThesecomponentsmakeiteasytowritenewJBIcomponents.

Drools:Droolscanbeusedtodorules-basedrouting.

Email:ProvidessupportforMIMEemailsending.

File:Itcanwritemessagestofilesinadirectory,orpollfiles,ordirectoriestosendmessagestoJBI.

FTP:ProvidesintegrationtoFTPviatheJakartaCommonsNetlibrary.

Groovy:HelpstouseGroovyscriptsasendpoints,transformers,orservices.

HTTP:HelpstoinvokerequestsonremoteHTTPserversandtoexposeJBIcomponentsoverHTTP.

Jabber:CanintegratewithJabbernetworkviatheXMPPprotocol.

JAXWS:UsestheJavaAPIforXML-basedwebservicestoinvokeawebserviceortohostaJava-basedwebserviceandexposeitovermultipleprotocols.

JCA:Providesaveryefficientwayofthreadpooling,transactionhandling,andconsumptiononJMSandotherresourceadapters.

JMS:HelpstosendandreceiveJMSmessages.

Quartz:UsedtoscheduleandtriggerjobsusingtheQuartzscheduler.

Reflection:ForIn-OnlyandIn-OutJBIcomponents,wecancreatedynamicproxies,whichwheninvokeddispatchthemessagesintotheJBIcontainer.

RSS:SupportsRSSandAtomviatheRomelibrary.

SAAJ:ProvidesintegrationwithSOAPwithattachmentsforJava(SAAJ)andApacheAxis.

Scripting:HelpstoscriptIn-OnlyorIn-OutmessageexchangesusingaJSR

223compliantscriptingenginesuchasJavaScript,Jython,orGroovy.

Validation:UsedtovalidatedocumentschemausingJAXP1.3andXMLSchemaorRelaxNG.

VFS:Providesintegrationwithfilesystems,jars/zips/bzip2,temporaryfiles,Samba(CIFS),WebDAV,HTTP,HTTPS,FTP,andSFTP.

WSIF:Providesawaytocallwebservices,hidingthedetailsofhowtheserviceisprovided.

XFire:ProvidesintegrationwithXFireSOAPstack.

XSLT:CandoXSLTtransformationforonenormalizedmessagetoanother.

XSQL:UseOracletoolforturningSQLqueriesintoXMLandfortakingXMLandinsertingorupdatingintoadatabase.

Theabovelistsarenotexhaustive,andthenumberofcomponentsaddedtothelistisincreasingdaybyday.ReadersareadvisedtorefertotheServiceMixwebsiteforupdatedinformation.WewilllookatafewamongsttheabovestandardandlightweightJBIcomponentsinsamplesorotherwise,aswewalkthroughdifferentchaptersinthistext.

YourFirstJBISample—BindinganExternalHTTPServiceIhopeallreaders,whethernoviceorprofessional,canunderstandandappreciatewhatwemeanbysayingaHTTPservice,otherwisemostprobablytheywillnotbereadingatextbooklikethis.Hence,IwillchooseaHTTPservicefordemonstrationpurposeshere.

Servlet-basedHTTPServiceAHTTPserviceisanetworkserviceaccessiblethroughtheHTTPprotocol.ServletsarethesimplestcomponentsavailableinJavawithwhichwecanbuildHTTPservice,andhencewewillusethathere.AssumingthatthereaderisfamiliarwithservletsandhowtodeployaHTTPserviceintheirfavoritewebcontainersuchasTomcat,onlythemajorstepsarelistedhere.Forfurtherdetailsthereaderisencouragedtorefertoanyavailableservlettechnologybooks.

Asthefirststep,wewillbuildanddeployaverysimpleservlet.Theservletcodeisgivenasfollows:

publicclassWelcomeServletextendsHttpServlet

{

publicstaticfinalStringXML_CONTENT="<?xml

version=\"1.0\"?><Name>Binil'sServletwishes

you</Name>";

publicvoidinit(ServletConfigconfig)throws

ServletException

{

super.init(config);

}

publicvoiddoGet(HttpServletRequestrequest,

HttpServletResponseresponse)

throwsServletException,IOException

{

doPost(request,response);

}

publicvoiddoPost(HttpServletRequestrequest,

HttpServletResponseresponse)

throwsServletException,IOException

{

System.out.println("WelcomeServlet.doPost...");

response.setContentType("text/xml");

response.setContentLength(XML_CONTENT.length());

response.setContentLength(XML_CONTENT.length());

PrintWriterout=response.getWriter();

out.println(XML_CONTENT);

out.flush();

}

}

Asshowninthecode,theservletsimplyspitsoutsomeXMLcontenttotheresponsestream,withoutevenlookingatthecontentsoftherequest.Equallysimpleistheweb.xmlfileanditisalsoshownhere:

<?xmlversion="1.0"encoding="ISO-8859-1"?>

<web-app>

<display-name>WAPExamples</display-name>

<description>WAPExamples.</description>

<servlet>

<servlet-name>WelcomeServlet</servlet-name>

<servlet-class>

com.binildas.esb.servicemix.servlet.WelcomeServlet

</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>WelcomeServlet</servlet-name>

<url-pattern>/hello/*</url-pattern>

</servlet-mapping>

</web-app>

Asafirststep,ifyouhaven'tdoneitbefore,editexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter),andchangethepathstheretomatchyourdevelopmentenvironment.

Nowtobuildthewebcomponent,changethedirectoryto

ch03\Servletandexecuteantscript.

cdch03\Servlet

ant

Here,weassumethatyouhaveinstalledthelatestversionofApacheAntbuildtoolandthebinfolderofthatisinyourpathenvironmentvariable.Thiswillgeneratethewebarchive(EsbServlet.war)andplaceitinthedistfolderinsidech03\ServletwhichcanbedeployedinthewebappsfolderofTomcat(oranyotherrelevantwebserver)andrestarttheserver.

TheHTTPservicewouldhavebeenexposedbynowandthesamecanbeaccessedusingyourfavoritebrowserwiththefollowingURL:

http://localhost:8080/EsbServlet/hello/

WecannowwriteClientcodesimilartowhatisshowninthefollowingcodetotesttheHTTPservice:

publicclassHttpInOutClient

{

privatestaticStringurl=

"http://localhost:8080/EsbServlet/hello/";

privatestaticStringfileUrl=

"HttpSoapRequest.xml";

protectedvoidexecuteClient()throwsException

{

InputStreaminputStream=

ClassLoader.getSystemResourceAsStream(fileUrl);

byte[]bytes=newbyte[inputStream.available()];

inputStream.read(bytes);

inputStream.read(bytes);

inputStream.close();

URLConnectionconnection=new

URL(url).openConnection();

connection.setDoOutput(true);

OutputStreamos=connection.getOutputStream();

os.write(newString(bytes).getBytes());

os.close();

BufferedReaderin=newBufferedReader(new

InputStreamReader(connection.getInputStream()));

StringinputLine;

while((inputLine=in.readLine())!=null)

{

System.out.println(inputLine);

}

in.close();

}

publicstaticvoidmain(String[]args)throws

Exception

{

if(args.length==2)

{

url=args[0];

fileUrl=args[1];

}

HttpInOutClienthttpInOutClient=new

HttpInOutClient();

httpInOutClient.executeClient();

}

}

NotethatwearetestingtheHTTPservicebysendingarbitraryXMLcontentasarequest,eventhough,anycharacterstreamwillbeacceptableasrequest.Thisisbecause,laterwewillbindthisservicetotheServiceMixESBandduringthattimemessageshavetoberoutedthroughtheNMR.Forthis,XMListhevalidnormalizedmessage.

Toruntheaboveclient,makesure(edit,ifrequired)theruntargetinthech03\Servlet\build.xmlfilematchesthefollowingcode:

<targetname="run">

<javaclassname="HttpInOutClient"fork="yes"

failonerror="true">

<classpathrefid="classpath">

<argvalue="

http:/localhost:8080/EsbServlet/hello/">

<argvalue="HttpSoapRequest.xml">

</java>

</target>

Now,executingantrunwillsendamessagetotheHTTPservice:

cdch03\Servlet

antrun

ConfiguretheHTTPServiceinServiceMixBeforeIstartdescribingthebindingofservicestoServiceMix,Iwouldliketoputoutonewordofcaution—thebindingcomponentsusedinthischapterareServiceMixlightweightcomponents.Theyaredeprecatedasofnow,andhenceforanyproductionconfigurationswehavetousestandardJBIcomponents,whichwillbecoveredindetailinsubsequentchapters.StillIamusingthesecomponentsbecausetheyare

simple,straightforward,intuitiveenough,andeasytoconfigureforanoviceuser.

AlltheServiceMixspecificbindingsaredoneinch03\HttpBinding\servicemix.xmlandletuslookstraightintothatinthefollowing:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:lb="http://servicemix.apache.org/demos/gettingstarted">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.

config.PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<importresource="classpath:activemq.xml">

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpeccomponentName="trace"

service="lb:trace">

<sm:component>

<beanxmlns="http:/xbean.org/schemas/spring/1.0"

class="org.apache.servicemix.components.util.

TraceComponent">

<sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="timer"

service="lb:timer"

destinationService="lb:httpGetData">

<sm:component>

<bean

class="org.apache.servicemix.components.quartz.

QuartzComponent">

<propertyname="triggers">

<map>

<entry>

<key>

<beanclass="org.quartz.SimpleTrigger">

<propertyname="repeatInterval"value="5000"/>

<propertyname="repeatCount"value="0">

<bean>

</key>

<beanclass="org.quartz.JobDetail">

<propertyname="name"value="MyExampleJob"/>

<propertyname="group"value="ServiceMix">

<bean>

</entry>

</map>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="httpGetData"

service="lb:httpGetData"

destinationService="lb:trace">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="org.apache.servicemix.

components.http.HttpInvoker">

<propertyname="url"

value="http://localhost:8080/EsbServlet/hello/">

<bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="httpReceiver"

service="lb:httpReceiver"endpoint="httpReceiver"

destinationService="lb:httpGetData">

<sm:component>

<beanclass="org.apache.servicemix.

components.http.HttpConnector">

<propertyname="host"value="127.0.0.1"/>

<propertyname="port"value="8912">

<bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

Letusnotlookatthecomplexitiesoftheaboveconfigurationuntillweactuallyruntheservice.Sowewilldeferdiscussionontheabovecodeuntillweseethecodeinaction.

RunServiceMixBasicJBIContainerBeforewebringupServiceMix,yourwebservershouldbeupandrunningwiththewebapplicationgeneratedintheprevioussectiondeployedsuccessfully.

WenowneedtoprepareServiceMixwithafewextralibraries.Forthat,dothefollowing:

Copy%SERVICEMIX_HOME%\components\lib\servicemix-components-3.1.1-incubating.jarto%SERVICEMIX_HOME%\lib\optional.

Open%SERVICEMIX_HOME%\components\servicemix-http-3.1.1-incubating-installer.zipandcopythefollowing.jarsto%SERVICEMIX_HOME%\lib\optional:

jetty*.jar

commons-codec*.jar

commons-httpclient*.jar

Copyquartz.jarfromtheQuartzdistribution(http://www.opensymphony.com/quartz/)to%SERVICEMIX_HOME%\lib\optional.

Now,togetServiceMixupwithcomponentsconfiguredintheXMLconfigurationshownabove,changedirectorytoch03\HttpBinding\andexecute%SERVICEMIX_HOME%\bin\servicemix

servicemix.xml.

WhatyouseeinthefollowingscreenshotisthecontentsofmyServiceMixconsole:

ThefirstpartoftheconsoleoutputisshowingServiceMixinitializingthecomponents,whichwehaveconfiguredpreviouslyinservicemix.xml.Thecomponentsbeinginitialized,inourcase,includetrace,timer,httpGetData,andhttpReceiver.Towardsthelatterpartoftheoutput,wecanseesomeXMLmessages.Infact,whatwehavedoneherebybringingServiceMixupis,wehavetriggeredamessageflowthroughvariouscomponentsconfiguredtotheexternalHTTPservice(inTomcatorso),retrievedtheXMLmessageandsenttotheconsoleoutput.

YouhavesuccessfullyinvokedanexternalHTTPservicethroughServiceMixESB!

RunaClientagainstServiceMixYoucanrepeatsendingmessagesthroughServiceMixESBbyrunningtheclientcodepackagedinthewebapplicationcodebase.Todothis,changethedirectorytoch03\Servlet.

ToruntheclientcodeagainstServiceMix,makesure(edit,ifrequired)theruntargetinthech03\Servlet\build.xmlisasshowninthefollowingcode:

<targetname="run">

<javaclassname="HttpInOutClient"fork="yes"

failonerror="true">

<classpathrefid="classpath">

<arg

value="http:/localhost:8912/EsbServlet/hello/">

<argvalue="HttpSoapRequest.xml">

</java>

</target>

Now,executingthefollowingcommandwillsendanothermessagethroughServiceMixESBtotheHTTPservice.

antrun

WhatJustHappenedinServiceMixThefollowingfigureshowshowweconfiguredvariouscomponentstotheServiceMixESBinservicemix.xml:

Asweknow,allmessageexchangehappensthroughtheNMR.Thedescriptionofvariouscomponentsfollows:

httpReceiver:Here,weconfigureorg.apache.servicemix.components.http.HttpConnector

classtolistentoaparticularport(8912inourcase),connectedtotheNMRusingaHTTPchannel.Thismeansanexternalclient(suchasHttpInOutClientinourcase)cansendHTTPrequeststotheNMRthroughthiscomponent.

httpGetData:org.apache.servicemix.components.http.HttpInvoker

performsHTTPclientinvocationsonaremoteHTTPsite.Asdescribedearlier,wehaveEsbServlet.wardeploymentcontainingWelcomeServletprovidingHTTPserviceintheremotesite.Thus,ineffecttheHttpInvokerfunctionsasabindingcomponentfortheremoteservice.

timer:org.apache.servicemix.components.quartz.QuartzCompo

nentisaQuartzcomponentfortriggeringcomponentswhentimereventsfire.Inourcase,wehaveconfiguredrepeatCountpropertywithavalueofzero,whichmeansthetriggerwillhappenonlyonce.

trace:org.apache.servicemix.components.util.TraceComponen

tisasimpletracingcomponent,whichcanbeplacedinsideapipelinetotracethemessageexchangethoughthecomponent.

Obviously,therearemultiplepathswhichwecandefineusingvariouscombinationsofthesecomponents.Wehaveconfiguredatypicaloneinservicemix.xmlsoastoenabletheclienttosendmessagesthroughthispipelinetotheremoteHTTPservice.WhentheclientsendsamessagetotheServiceMixESB,itreachestheNMRthroughthehttpReceivercomponent.ThedestinationServiceforhttpReceiverishttpGetData,hencethemessageisroutedtohttpGetData.However,httpGetDataisaninvokertotheremoteHTTPService.ThisendsupininvokingtheremoteHTTPservicepassingthemessageparameters.Theservicegetsinvokedandanyresponseisroutedbackthroughasimilarpipelinebacktotheclient.

SpringXMLConfigurationforServiceMixServiceMixusesXMLconfigurationfiles.From2.0onwards,ServiceMixusetheXBeanlibrarytodotheXMLconfiguration.Thus,thesimplestwaytostartusingServiceMixtowiretogetherJBIcomponentsisviaSpringandtheXMLconfigurationfilemechanismfromSpring.

Wewillnowlookatthedetailsofhowwehaveconfiguredcomponentstogether.First,weintroduceafewnewXMLtagsforJBIconfigurationsuchascontainerandactivationSpecs,butapartfromthat,youcanusealltheregularSpringconfigurationtags—beans,bean,property,andvalue.Forexample,insidethe<component>tagyoucanconfigurepropertiesonthe

component.Acomponentcanhave<bean>tagwithnested<bean>tagandsoon.ThisallowsyoutomixandmatchregularSpringconfigurationofPOJOswiththeServiceMixJBISpringconfigurationmechanism.

ThetableshowninthefollowinglistsoutafewkeyattributedetailsfortheJBIcontainerelement.TheServiceMixwebsitewillgivedetailsontheelementsandattributeswhicharenotdescribedhere.AlsothebeanwiringdetailsinSpringstyleandall,arenotdescribedhere,sinceweassumethatthereaderisfamiliarwiththat.Ifnot,anyothertextbookonSpringwillhelpyouhere.

Sr.No.

KeyAttributeName

AttributeType

Description

1

name

String

DenotesnameoftheJBIcontainer.Thishastobeuniqueifitisrunninginaclusterconfiguration.ThedefaultnameisdefaultJBI

2

useMBeanServer

Boolean

Ifsettotrue,ServiceMixwilltrytofindanMBeanServerfromtheMBeanServerFactoryifoneisnotsupplied

3

create

Bool

Ifsettotrue,ServiceMixwillcreateit'sown

3

createMBeanServer

Boolean

Ifsettotrue,ServiceMixwillcreateit'sownMBeanServerifoneisnotsuppliedtothecontainerorfoundfromanMBeanServerFactory

4

rmiPort

Int

Thisistheportusedforthermiregistry(andthus,theJMXconnector)andthedefaultisto1099.

TheServiceMixcomponentmaybegivenfollowingnames:

ComponentName

Service

Endpoint

DestinationService

Wemayalsousethefollowinginacomponenttospecifyitsrouting:

destinationService

destinationInterface

destinationOperation

ThePropertyPlaceholderConfigurerreadsSERVICEMIX_HOME\conf\servicemix.properties

file,whichcontainsvaluesforcommonlyusedenvironmententriessuchasrmi.portorjmx.url.

Aswelookintomoresamplesinsubsequentchapters,youwillbetterunderstandthemechanismofwiringservicesintheJBIbusandhowwecanroutemessagesthroughtheseservices.

SummaryJustlikeanEJBcomponentlivesinanEJBcontainer,aJBIcomponentlivesinaJBIcontainer.AJBIcontainerprovideshostingfacilitiesforaJBIcomponentandcontrolthelifecycleofthecomponent.MultiplevendorsprovidetheirownimplementationsoftheJBIcontainer.

ServiceMixistheonewehaveseenhereindetail,whichwewillbecontinuinginthisbookforthepurposeofshowingJBIusingexamples.JustlikethescenarioyouhavealreadyseeninthischapterofbindinganexternalHTTPservicetotheJBIcontainer,wecanalsobindmanyotherprotocolsandformattedcomponentstotheJBIcontainer,thusprovidingaServiceWorkbenchattheJBIcontainer-level.However,theinterestingparttobenotedisthatevenbeforeJBI,wehavebeendoingbindingandintegrationofdifferentkindsofservicesinmultipleways.

Thenextchapterisdevotedtore-lookathowwehavebeendoingthings,withoutafullfledgedJBIcontainer.ThiswillhelpyoutogetabroaderpictureoftheasisstateofJBI;fromtherewewilldigmoreintoJBIandrelatedservices.

Chapter4.Binding—TheConventionalWayBindingserviceslocallyorremotelyisnotaninnovationbroughtbyESBorJBI,butwehavebeendoingitinmultiplewaysallthroughtheyears.Inthischapter,wewillexplorethemeaningof"Binding"andthenlookathowwecanbindaremotelyavailableservice(intheformofanEJBcomponent)toamiddle-tierandexposeitthroughafirewallfriendlychannellikeHTTP.Bytheendofthechapter,youwillappreciatehowanextraindirectionwithasuitabletunnelingwillhelptoexposeeventechnologyspecificAPIservices,sothattheservicebecomestechnologyagonistic.

Wewillcoverthefollowinginthischapter:

Meaningofbinding

ApacheSOAPbinding

BindingastatelessEJBservicetoApacheSOAP

Runningthesample

Binding—WhatitMeansWewillconsidertheverybasicrequirementoftwoapplicationsortwoservicesinteracting—toexchangemessages.Applicationssharedataintheformofmessages.

Oneoftheapplicationssendsmessageswhiletheotherreceivesit.Messagesareexchangedbetweenasenderapplicationandareceiverapplicationoveramessagingchannel.Letuslookatbindinginthiscontext.

BindingApplicationsconnecttothemessagingchannelthroughamessageEndpoint.TheprocessofconnectinganapplicationorservicetoasuitableEndpointiscalled'binding'.Inmoretechnicalterms,abindingwilldefinehowPortType(abstractinterfaceoftheservice)isboundtoaparticulartransportprotocolandanencodingschema.Abindinginteractioninvolvesaservicerequesterandprovider.Whenanapplicationusestheservicedescriptiontocreateamessagetobesenttotheserviceprovider,wearebindingtotheservice.

EndpointsSincemultipleapplicationsorservicesinteractwitheachotherthroughamessagingchannel,theyhavetodealwithmultipletransportmechanismsandmessageformats.Endpointsdothefunctionalityofconvertingmessagesfromoneformatto

another.Thustherestoftheapplicationknowslittleaboutmessageformats,messagingchannels,oranyotherdetailsofcommunicatingwithotherapplicationswhentheyexchangemessages.Sinceendpointsdothismessagenormalizationfunctionality,amessageendpointcodeiscustomtoboththeapplicationandthemessagingsystem'sclientAPI.

WhenwewriteaprogramtoamessagingAPIsuchasJMS,we'redevelopingendpointcode.Thisinvolveseitherdevelopinglow-levelplumbingcodebyhandorusingappropriateclientAPIsandrun-timetoolstoautomaticallygeneratecode.Later,wewillseethatawholelotofendpointsareavailable,asofftheshelfcomponentsalongwithmessagebusproductslikeServiceMix.Inthischapter,wewilllookatrawformsofbindingservice.Thisexamplehelpustounderstandwhatweactuallymeanbybinding.

ApacheSOAPBindingAssaidearlier,withoutusingaJBIoranESBframework,letusseebindinginactionusingtheApacheopen-sourceSOAPstack.

AWordaboutApacheSOAPApacheSOAPisanimplementationbasedontheSOAPsubmissiontoW3C(WorldWideWebConsortium).ThissubmissionhasbeenproducedbytheXMLProtocolWorkingGroup,whichispartoftheWebServicesActivity.IBM

AlphaworksfirstbroughtaJavareferenceimplementationoftheSOAP1.1specification,whichiscontributedtoformtheApacheSOAPproject.

SOAPisalightweightprotocolfortheexchangeofinformationinadecentralized,distributedenvironment.SOAPisbasedonXMLandconsistsofthreeparts—anenvelope(containingandoptionalHeaderandamandatoryBody)thatdefinesaframeworkfordescribingwhatisinamessageandhowtoprocessit,asetofencodingrulesforexpressinginstancesofapplication-defineddatatypes,andaconventionforrepresentingremoteprocedurecallsandresponses.

ApacheSOAPFormatandTransportsApacheSOAPsupportsthreeencodingstyles:

1. XMIencoding:This(availablewhenusingJava1.2.2)providessupportforautomaticmarshallingandunmarshallingofarbitraryobjects.

2. SOAPencoding:Built-insupportisprovidedforencoding/decodingprimitivetypeslikeStringsandInteger,arbitraryJavaBeans(usingreflection)andone-dimensionalarraysofthesetypes.Forothertypes,theusercanhandwriteencoders/decodersandregisterwiththeXMLSOAPruntime.

3. LiteralXMLencoding:AllowsustosendXMLelements(DOMorg.w3c.dom.Elementobjects)asparametersbyembeddingtheliteralXMLserializationoftheDOMtree.

ApacheSOAPsupportsmessagingandRPCovertwotransports—HTTPandSMTP.AspertheSOAPspecification,

allSOAPimplementationsshouldsupportSOAPXMLpayloadoverHTTPTransport.Asoptionalfeatures,implementationsarefreetosupportothertransportbindingslikeJMS,FTP,andSMTP.Vendorscanevensupportproprietarytransportbindingsforwhatsoeverreasontheyhave,sothereshouldbenothingwhichpreventsonefromnotexposingXMLSOAPevenoverradiowavesasatransportmechanism!

RPCandMessageOrientedAnApacheSOAPserviceorbindingcanbeRPCormessageoriented.

IfitisRPCoriented,theruntimeexpectsastrict,SOAPformattedrequest(andresponsetoo).TheruntimewillprocesstheSOAPenvelope,dispatchtheRPCmethodcallrequesttotheappropriateserviceimplementationclassandtotheappropriatemethod.ForwardtheresponsebacktotheSOAPclient.

Ifitisamessageoriented,requestandresponse,theyaretransportedinadocumentstyle—wehavefreedomtoembedarbitraryformatsofmessageinsidetheSOAPenvelope.ThatmeanstheruntimewillpassthroughtheSOAPbodytotheserviceimplementation,anditisthedutyoftheserviceimplementationtoprocessthecontentsoftheSOAPEnvelope.

BindingServices

ApacheSOAPutilizesdeploymentdescriptorsintheformofXMLfilestoprovideinformationtotheSOAPruntimeabouttheservicesthatshouldbemadeavailabletoclients.TheycanprovideawidearrayofinformationsuchastheUniformResourceNames(URN)fortheservice(whichisusedtoroutetherequestwhenitcomesin),methodandclassdetails,iftheserviceisbeingprovidedbyaJavaclassorthemethod.Moreover,theEJBJNDIname,iftheserviceisbeingprovidedbyanEJB.TheexactcontentsofthedeploymentdescriptordependuponthetypeofartifactwhichisbeingexposedviaSOAP.

NOTENOTE

URNsareintendedtoserveaspersistent,location-independentresourceidentifiers

ApacheSOAPsupportsthefollowingartifactsasservicestobeboundtotheruntime:

StandardJavaclasses

EJBs

BeanScriptingFramework(BSF)supportedscript

Theserviceelementistherootelementofthedeploymentdescriptorandisshowninthefollowingcode:

<isd:service

xmlns:isd="http://xml.apache.org/xmlsoap/deployment"

id="urn:ejbhello">

<!--othercodegoeshere-->

</isd:service>

Theserviceelementcontainsanidattributewhichisusedtospecifythenameoftheservice.SOAPclientsusethevalueoftheidattributetorouterequeststotheservice.WewillusetheURNsyntaxtospecifythenameoftheserviceasurn:ejbhello.TheserviceelementcanalsocontainanoptionaltypeandanoptionalcheckMustUnderstandsattribute.

TheoptionalcheckMustUnderstandswillmandatewhethertheservershouldunderstandaparticularSOAPheaderinthemessage.Ifthereceivercannotrecognizetheelement,itmustfailwhenprocessingtheheader.TheserverwillthrowaSOAPfault,ifthereareSOAPheadersinaSOAPrequestmessagethathavethemustUnderstandattributesettotrue.

Theproviderelementisthemostimportantelementwhichcontainsattributesandsub-elementsthatspecifythedetailsoftheartifactthatisimplementingtheservice.Theproviderelement,attributes,andsub-elementsareshowninthefollowingcode:

<isd:providertype="org.apache.soap.providers.

StatelessEJBProvider"scope="Application"

methods="hello">

<isd:optionkey="JNDIName"

value="sample-statelessSession-TraderHome">

<isd:optionkey="FullHomeInterfaceName"

value="samples.HelloServiceHome">

<isd:optionkey="ContextProviderURL"

value="t3://localhost:7001">

<isd:optionkey="FullContextFactoryName"

value="weblogic.jndi.WLInitialContextFactory">

</isd:provider>

Thetypeattributeoftheproviderelementtellstheruntimewhichproviderimplementationhastobeusedatruntime.Theavailableprovidersare:

java

script

org.apache.soap.providers.StatelessEJBProvider

org.apache.soap.providers.StatefulEJBProvider

org.apache.soap.providers.EntityEJBProvider

Thenestedelementswithintheproviderelementsarespecifictothetypeofartifactusedtodefinetheserviceandareselfexplanatory.

SampleBindaStatelessEJBServicetoApacheSOAPInthissection,wewillwalkthroughasamplebindingscenariowhichwillhelpustounderstandbindingofservices.

SampleScenarioThesamplewillmakeuseofthefollowingrun-timesetups:

ApacheSOAPinTomcat

EJBcontainerinBEAWeblogic

AstatelesssessionEJB(HelloServiceBean)isdeployedinBEAWeblogicServerwhichexposesasinglemethod,shownasfollows:

publicStringhello(Stringphrase)

HelloServiceBeanexposesanEndpoint.ThisEndpointconnectstoaWeblogicspecifict3channel.t3channelcanpassthrought3protocol,forobjectserviceaccess.LetusassumethatwehavearequirementofaccessingtheaboveEJBservicethroughaHTTPchannel(forsomereasonlikeafirewallrestrictionbetweentheserverandtheclient).Wecansolvethisproblembymakinguseofawebserverinfrastructure.

Eventhoughwecanusedifferentwebserversetups(evenWeblogic'swebcontainercanbeusedforthis)toachievethis,wewilluseApacheTomcatforourdemo.TomcatwillhostApacheSOAPasaninternalwebapplication.WewillcreateaservicebindinginsidetheApacheSOAPruntimeinTomcattobindtheEJBservice.Thismeans,wecanchainaHTTPchannelusingasuitablebindingtothet3channel.DoingsowillallowclientstospeaktheHTTPlanguagetoservicebindinginTomcatthroughHTTPchannel,andTomcatwillinturntranslatetheHTTPprotocoltot3protocolandpassthroughthemessagetothet3channel.SothatthemessagewillultimatelyreachtheEJBcomponenthostedinWeblogicapplicationserver.

Theentirescenarioisrepresentedinthefollowingfigure:

Thedeploymentforthesamplerequirementwilltranslatetothatshowninthefollowingfigure:

CodeListingInthissection,wewillwalkthroughthemaincodeusedforthedemo.Allthecodediscussedhereisinthefolderch04\AxisSoapBindEjb:

SessionEJB:TheHelloServiceBean.javaclassisshownhere:

publicclassHelloServiceBeanimplements

SessionBean

{

publicStringhello(Stringphrase)

{

System.out.println("HelloServiceBean.hello{"

+(++times)+"}...");

return"FromHelloServiceBean:HELLO!!You

justsaid:"+phrase;

}

}

TheHelloServiceBean.javaisasimplestatelesssessionEJBandhenceisstraightforward.

<weblogic-ejb-jar>

<weblogic-enterprise-bean>

<ejb-name>statelessSession</ejb-name>

<enable-call-by-reference>True</enable-call-

by-reference>

<jndi-name>sample-statelessSession-

TraderHome</jndi-name>

</weblogic-enterprise-bean>

</weblogic-ejb-jar>

WewilldeploytheEJBinWeblogicserver(eventhoughthesameEJBcanbedeployedinanycompatibleEJBserverlikeWebsphereorJBoss)andhencewerequiretheweblogic-ejb-jar.xmlasshownabove.Themostimportantthingtonotehereisthejndi-namewhosevaluewehaveconfiguredassample-statelessSession-TraderHome.

ApacheSOAPBinding:TheDeploymentDescriptor.xmlcontainsentriesasshowninthefollowingcode:

<?xmlversion="1.0"?>

<isd:service

xmlns:isd="http://xml.apache.org/xmlsoap/deployment"

id="urn:ejbhello">

<isd:provider

type="org.apache.soap.providers.

StatelessEJBProvider"

scope="Application"methods="hello">

<isd:optionkey="JNDIName"

value="sample-statelessSession-TraderHome">

<isd:optionkey="FullHomeInterfaceName"

value="samples.HelloServiceHome">

<isd:optionkey="ContextProviderURL"

value="t3://localhost:7001">

<isd:optionkey="FullContextFactoryName"

value="weblogic.jndi.WLInitialContextFactory"

>

</isd:provider>

<isd:faultListener>

org.apache.soap.server.DOMFaultListener

</isd:faultListener>

</isd:service>

Here,wecannotethatwehavegiventhevaluesample-statelessSession-TraderHomeforthekeyJNDIName.So,herewearereferringtotheEJBservicewedeployedpreviously.Wehaveconfiguredweblogic.jndi.WLInitialContextFactory,whichcancreateinitialcontextsforaccessingtheWebLogicnamingservice.

Wehaveconfiguredorg.apache.soap.providers.StatelessEJBProv

iderforbindingtheEJBservicetospeakSOAPprotocol.StatelessEJBProviderimplementsthetwomethodsdefinedinorg.apache.soap.util.Provider,thatisshowninthefollowingcode:

publicinterfaceProvider

{

publicvoidlocate(DeploymentDescriptordd,

Envelopeenv,Callcall,StringmethodName,

StringtargetObjectURI,SOAPContextreqContext)

throwsSOAPException;

publicvoidinvoke(SOAPContextreq,SOAPContext

res)throwsSOAPException;

}

Aprovider'sfunctionissplitintotwopieces—locatingthe

service(whichalsoincludesanyverificationthattheservicecanbeexecuteatallandbytheclient),andactuallyrunningit.It'suptotheinvokemethodtocalltheactualserviceuptograbandformattheresponseintoaSOAPresponseobject.

Duringinitialization,StatelessEJBProviderwilldothefollowingtogetaremotereferencetotheEJBcomponent:

EJBHomehome=(EJBHome)

PortableRemoteObject.narrow(contxt.

lookup(jndiName),

Class.forName(homeInterfaceName));

MethodcreateMethod=home.getClass().

getMethod("create",newClass[0]);

remoteObjRef=(EJBObject)

createMethod.invoke((Object)home,new

Object[0]);

DuringactualmethodinvocationStatelessEJBProviderwillexecutethefollowingcode:

Methodm=MethodUtils.getMethod(remoteObjRef,

methodName,argTypes);

Beanresult=newBean(m.getReturnType(),

m.invoke(remoteObjRef,args));

RunningtheSampleAsafirststepandifyouhaven'tdoneitbefore,editexamples.PROPERTIESprovidedalongwiththecodedownloadforthischapterandchangethepathstheretomatch

yourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Runningthesampleinvolvesmultiplesteps,asshownasfollows:

DEPLOYINGTHEEJBFordeployingtheEJB,wehavetofollowgeneralEJBdeploymentstepsasspecifiedintheWeblogicdocumentation.

SinceyouarebuildingyourfirstEJBsampleinthisbook,wewillspendalittlemoretimetohelpyoutodeployyourEJBsample.First,changedirectorytotheEJBsamplesdirectory.

cdch04\AxisSoapBindEjb\ejb

Now,settheenvironmentvariablesforthebuildconsoleaspertheWeblogicdocumentationandthenusetheantscriptprovidedalongwiththeWeblogicserverbundle.Forthat,dothefollowing:

%wl.home%\samples\domains\examples\setExamplesEnv

.bat

%wl.home%\server\bin\ant

AssumingthatyouareusingtheWeblogic8.xversion,theabovestepsshouldhavebuilttheEJBbynow.IfyouuseadifferentversionoftheEJBserver,orifyouuseadifferent

vendor'sEJBserver,refertothedocumentationstheretomakechangestothebuildexercise.

WecaneventestwhetherourEJBdeploymentwentfinebyexecutingatestclient,like:

cdch04\AxisSoapBindEjb\ejb

%wl.home%\server\bin\antrun

BINDEJBTOSOAPWewillusetheApacheSOAPimplementationforthisdemonstration.FromtheApacheSOAPdistribution,copythesoap.warfileanddeploythattothewebappsfolderofyourfavoritewebserver(ApacheTomcat).Youalsoneedtocopythefollowingfilesandmakethemavailableinthelibfolderofyourwebserver:

%wl.home%\server\lib\weblogic.jar

%wl.home%\samples\server\examples\build\clientclasses\

sample_statelessSession_client.jar

Nowrestartyourwebserver.

ApacheSOAPprovidesServiceManagerClientusingwhichwecanregistertheremoteEJBbindingtotheSOAPenvironment.Thefollowinganttaskdoesexactlythis:

<targetname="deploy"depends="compile">

<java

classname="org.apache.soap.server.ServiceManagerClient"

fork="true">

<arg

value="http://localhost:8080soapservlet/rpcrouter">

<argvalue="deploy">

<argvalue="DeploymentDescriptor.xml">

<classpath>

<pathrefid="classpath">

</classpath>

</java>

</target>

Thisanttargetcanbeinvokedbytyping:

cdch04\AxisSoapBindEjb\SoapBind

antdeploy

TheServiceManagerClientintheabovedeploytargettakesthreeparameters—theURLtotheSOAPserver,thecommanddeploy,andthefilecontainingyourdeploymentdescriptor.ThefirstparameterspecifiestheURLoftheApacheSOAPRPCrouter,whichwillhelpinroutingclientrequeststotherequestedservice.ThesecondparameterspecifiestheoperationthattheServiceManagerClientshoulddo.Thedeployoperationregisterstheserviceusingthedeploymentinformationlocatedinafilespecifiedbythethirdparameter.Inourcase,thefileiscalledDeploymentDescriptor.xmlanditcontainsthedeploymentdescriptorforthehelloService.

Onceyouhaveexecutedthedeploycommand,youcan

executethelistcommand.Youshouldnowseeoutputlistingurn:ejbhello,whichistheuniqueIDofyourservice.Youcanalsoviewthisservicefromthewebadmintoolbygoingtohttp://localhost:8080soapadmin/index.html

andselectingtheListbutton.Thelistanttargettoexecutethelistcommandisasfollows:

<targetname="list">

<java

classname="org.apache.soap.server.ServiceManagerClient"

fork="true">

<arg

value="http://localhost:8080soapservlet/rpcrouter"/>

<argvalue="list">

<classpath>

<pathrefid="classpath">

</classpath>

</java>

</target>

Wecanverifywhetherthedeploymentwassuccessfulbytypingthefollowing:

antlist

RUNTHECLIENTTheclientcreatesaCall,setsparameters,andinvokestheservicebindingasshowninthefollowingcode:

URLurl=newURL(args[0]);

Callcall=newCall();

call.setEncodingStyleURI(Constants.NS_URI_SOAP_ENC);

call.setTargetObjectURI("urn:ejbhello");

call.setMethodName("hello");

Vectorparams=newVector();

params.addElement(newParameter("phrase",

String.class,"what'syourname?",null));

call.setParams(params);

Responseresp=call.invoke(url,"");

Parameterresult=resp.getReturnValue();

Therunanttargetwillexecutetheclientcode.

<targetname="run">

<javaclassname="samples.ejb.SoapTest"

fork="true">

<arg

value="http://localhost:8080soapservlet/rpcrouter">

<classpath>

<pathrefid="classpath">

</classpath>

</java>

</target>

Toruntheclient,type:

antrun

WhatJustHappenedIfeverythingwentfine,youwouldseesomethingsimilarto

theresultasshowninthefollowingscreenshot:

TheSoapTesthasactuallycreatedaSOAPrequestandroutedittotheservicebindingwithinSOAPruntime.TheformatofthisSOAPrequestisasfollows:

POSTsoapservlet/rpcrouterHTTP/1.0

Host:localhost:8080

Content-Type:text/xml;charset=utf-8

Content-Length:458

SOAPAction:""

<?xmlversion='1.0'encoding='UTF-8'?>

<SOAP-ENV:Envelopexmlns:SOAP-ENV=

"http://schemas.xmlsoap.orgsoapenvelope/"

xmlns:xsi="http://www.w3.org/2001/XMLSchema

-instance"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<SOAP-ENV:Body>

<ns1:helloxmlns:ns1="urn:ejbhello"

SOAP-ENV:encodingStyle=

"http://schemas.xmlsoap.orgsoapencoding/">

<phrasexsi:type="xsd:string">

what&apos;syourname?

</phrase>

</ns1:hello>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

AHTTP-basedSOAPendpointisidentifiedbyaURL.ThisURL,inourcase,intheaboverequestishttp://localhost:8080soapservlet/rpcrouter

.SOAPMethodNameisanoptionalheader,whichuniquelyidentifiesthemethodname.ForHTTPtransport,SOAPmessagesaresentoverPOSTmethod.TheSOAPmessagebodywillcontaintheXMLformattedcontentrequiredfortheSOAPruntimetoinvoketherequestedmethod.

IntheSOAPcontent,therootelementisanelementwhosenamespace-qualifiedtagname(ns1:helloinourcase)matchestheoptionalSOAPMethodNameHTTPheader.ThisredundancyisprovidedtoallowanyHTTPinfrastructureintermediarieslikeproxies,firewalls,webserversoftware,toprocessthecallwithoutparsingXML,atthesametimealsoallowingtheXMLpayloadtostandindependentoftheenclosingHTTPmessage.

Uponreceivingthisrequest,theStatelessEJBProvidercomes

intoaction.theStatelessEJBProviderunmarshallstheSOAPBodycontentandretrievesthemethodparameters.IttheninvokestheEJBservice,whichisremotelyboundtotheSOAPruntime.TheresultsarethenpackagedbacktoaSOAPresponsebodyandsentbacktotheclient.

TheSOAPresponseisshowninthefollowingcode:

HTTP/1.1200OK

Server:Apache-Coyote/1.1

Set-Cookie:

JSESSIONID=929DAB0C201F82C9B3F575C8276692A1;

Path=/soap

Content-Type:text/xml;charset=utf-8

Content-Length:523

Date:Thu,26Oct200608:20:23GMT

Connection:close

<?xmlversion='1.0'encoding='UTF-8'?>

<SOAP-ENV:Envelopexmlns:SOAP-ENV=

http://schemas.xmlsoap.orgsoapenvelope/

xmlns:xsi="http://www.w3.org/2001/

XMLSchema-instance"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<SOAP-ENV:Body>

<ns1:helloResponsexmlns:ns1="urn:ejbhello"

SOAP-ENV:encodingStyle=

"http://schemas.xmlsoap.orgsoapencoding/">

<returnxsi:type="xsd:string">

FromHelloServiceBean:

HELLO!!Youjustsaid:what&apos;syourname?

</return>

</ns1:helloResponse>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

Asyoucanseeabove,theSOAPresponsedoesn'thaveany

SOAPspecificHTTPheaders.ThepayloadwillcontainanXMLdocumentthatcontainstheresultsoftheoperationinvoked.TheresultswillbeinsideanelementwiththenamematchingthemethodnamesuffixedbyResponse.

HowtheSampleRelatestoServiceMixInthissample,wesawhowtouseconventionaltoolslikeanEJBcontainer,ApacheSOAPtoolkit,andApacheTomcatwebcontainertobindanexternalEJBserviceremotelyintoSOAPruntimeandexposetheserviceoveraHTTPtransportchannel.Later,wewillseethatthesamefunctionalitycanbedonewithoutallthesehasslesanddeploymentsteps,butwithjustfewcomponentconfigurationsinServiceMix.Theideabehindthisexampleistomakethereaderfamiliarwiththetechnicalcasebehindtheneedforservicebindingandalsotoreckonthatservicebindingisnotanewconcept,butsomethingwehavebeendoingforalongtime.

SummaryInthischapter,wediscussedasimplebindingscenariobywhichwecanmakeanEJBserviceaccessibleacrossthefirewalltotheoutsideworld.IfyouhaveanApacheSOAPimplementationwithyou,youcanalsotryoutthesamplesandseetheresults.Similartowhatwedidinthissample,attimesweneedtotunnelorredirectservicesthroughintermediaries

eitherduetoprotocolorformatmismatchesorduetosomeotherreasons.

Alltheseactivitiesareconcernsapartfromyourbusinesslogiccodingandneedtobeaddressedatyourapplicationframework-level.Inthischaptertoo,wehaveperformeditinthesamemanner,butwehavedonealotofstepstoconfigurethewebserverwithApacheSOAP.Later,whenyougothroughtheJBIandESBsamplesyouwillrealizethatthesamefunctionalitycanbeachievedbyselectingandconfiguringsuitableJBIcomponents.

ESBimplementationslikeServiceMixmakeuseofnewgenerationSOAPframeworkswhichbindbinaryservicessuchasEJBandPOJOtotheJBIbustomakeitSOA-compliant.

Inthenextchapter,wewilldelvemoreintosuchaSOAPframeworknamelyXFireandlookatsomeveryusefulmediationfeaturesofit.Inthelaterchapters,wewillleveragesimilarfeaturesfromtheJBIbusstraightaway.

Chapter5.SomeXFireBindingToolsJBIadvocatesthatXMLdatabasedonaWSDLmodelshouldbeflowingthroughtheNMR.Hence,areferencetoanappropriateSOAPframeworkcapableofunderstandingWSDLandgeneratingWSDL-compliantformatteddataisimportantinanyJBIdiscussion.

ServiceMixhasthebestintegrationwithXFire,whichisthenewgenerationJavaSOAPframework.SincetheAPIiseasytouseandsupportsstandards,XFiremakesSOAdevelopmentmucheasierandstraightforward.Itisalsohighlyperformanceoriented,sinceitisbuiltonalowmemoryStAX(StreamingAPIforXML)model.Currently,XFireisavailableinversion2.0underthenameCXF.Inthischapter,wewillnotdiscussanyJBIspecificbindingmethods;insteadwewillconcentrateonXFireandlookathowwecanusethesameforintegrationsolutions.

Onceweappreciatethis,wewillbetterunderstandwhatpartoftheintegrationfunctionalitycanbedoneusingXFirewithintheJBIarchitecture.

Wewillcoverthefollowinginthischapter:

BindinginXFire

WebserviceusingXFireConfigurableServlet

WebserviceusingXFireSpringXFireExporter

WebserviceusingXFireSpringJsr181handler

XFireExportandbindEJB

XFireforlightweightintegration

BindinginXFireInXFireterms,bindingsarewaystomapXMLtoJavaobjects.Currently,XFiresupportsthefollowingbindings:

Aegis:AegisisthedefaultXFirebindingwhichmapsXMLtoPOJOs.ItsupportscodefirstdevelopmentwhereyouwriteyourserviceinPOJOsandAegiswillgeneratetheXMLschemaorWSDLforyou.IthasaflexiblemappingsystemsothatyoucancontrolhowyourPOJOsarebound.

JAXB:JAXBisthereferenceimplementationoftheJAXBspecification.XFireintegrateswithJAXB1.0and2.0.

XMLBeans:XMLBeansisanApacheprojectwhichtakestherichness,features,andschemaofXMLandmapsthesefeaturesasnaturallyaspossibletotheequivalentJavalanguageandtypingconstructs.

Message:TheMessageBindinghasspecialsemanticstoallowyoutoworkwithXMLstreamsandfragmentsveryeasily.TheMessageBindingtakestheXMLStreamReaderfromtherequestandprovidesitdirectlytoyourclasses.

Castor:CastorprovidesmarshallingandunmarshallingofXMLandJavaobjectswhichdoesn'trequirerecompilationoftheJavacodeifthemappingdefinitionchanges.HencesystemswheretheservicelayerisbeingdevelopedindependentlyfromthebusinesslayercanbenefitmuchusingCastor.

Adetaileddescriptionoftheaboveframeworksisbeyondthescopeofthisbook,butweneedtolookatwhatXFirehastoofferandhowthisisgoingtohelpusinbindingservicesand

componentstotheServiceMixESB.

XFireTransportsXFireprovidesmultipletransportchannelsforcommunicationsandisbuiltonanXMLmessaginglayer.Themaintransportmechanismsarelistedasfollows:

HTTP:StandardXMLinSOAPformatoverHTTP

JMS:Asynchronousandreliablewayofsendingmessages

XMPPorJabber:AnasynchronousmessagingmechanismforSOAP

AServiceRegistryisthecentralpartoftheXFiremessaginginfrastructure.Userscansendmessagesthroughanyoftheavailabletransportchannels.ThetransportlooksattheservicebeinginvokedandpassesaMessageContextandservicenameofftotheXFireclass.TheXFireclasslooksuptheservicefromtheServiceRegistryandtheninvokestheappropriatehandler.ThusXFiretransportisresponsibleformanagingincomingandoutgoingcommunicationsusingaparticularwireprotocol,whichisshownasabstractinthemethodsignatureinthefollowingcode:

publicinterfaceTransportextends

ChannelFactory,HandlerSupport

{

BindingfindBinding(MessageContextcontext,

Serviceservice);

}

JSR181andXFireJavaWebServicesMetadata(WSM,basedonJSR181)isbuiltoverJavaLanguageMetadatatechnology(JSR175).TheintentionbehindJSR181istoprovideaneasytousesyntaxfordescribingwebservicesatthesource-code-levelfortheJ2EEplatform.Thus,WSMleveragesthemetadatafacilityinJavatowebservices.Inotherwords,aJavawebserviceisjustaPlainOldJavaObject(POJO)withafewannotations.Theannotationscandescribethewebservicename,detailsaboutthemethodsthatshouldbeexposedinthewebserviceinterface,parameters,theirtypes,thebindings,andothersimilarinformation.XFireiscontinuouslyaddingsupportforJSR181andthischapteralsogivesanintroductiontothis,withworkingexamples.

Wewillwalkthroughfourdifferentbutrelatedworkingsamples.AllofthemdemonstratecapabilitiesofXFire.TheparttonoticeisthesimplicitywithwhichwecangetthingsdonewithXFire.

WebServiceUsingXFireConfigurableServletWebservicesaretoagreatextentinthespiritofSOA.MostwebservicesframeworksinternallyusesaSOAPstackfortransportandformathandling.SinceXFireisaSOAPstackcapableofeasilybuildingwebservices,letuslookintoonesampledoingthathere.

SampleScenarioOuraimhereistoexposeaPOJOaswebserviceusingXFire—org.codehaus.xfire.transport.http.XFireC

onfigurableServlet.

CodeListingXFireConfigurableServletexpectsaservicedefinitionintheformofanxmlfilecalledservices.xml.XFirebyitselfisaweb-basedapplication;hencewearegoingtopackagethesampleapplicationasastandardwebarchive.

Wewillnowlookatthecontentsoftheindividualartifactsthatmakeupthewebarchive:

1. IHello.class:IHelloisasimpleJavainterface,declaringasinglemethodsayHello.

Thisisshowninthefollowingcode:

publicinterfaceIHello

{

StringsayHello(Stringname);

}

2. HelloServiceImpl.class:HelloServiceImplimplementstheIHellointerfaceandhassomeverbosecodeprintingoutdetailsintotheserverconsole.

Thefollowingcodedemonstratesit:

publicclassHelloServiceImplimplements

IHello

{

privatestaticlongtimes=0L;

publicHelloServiceImpl()

{

System.out.println("HelloServiceImpl.HelloServiceImpl()...");

}

publicStringsayHello(Stringname)

{

System.out.println("HelloServiceImpl.sayHello("

+(++times)+")");

return"HelloServiceImpl.sayHello:HELLO!

Youjustsaid:"+name;

}

}

3. services.xml:Herewespecifythedetailsofourwebservices,usingtheserviceClassandimplementationClasselements.serviceClassspecifiestheJavainterface,whichhoststhemethodsignaturewhereasimplementationClassspecifiestheclasswhichimplementsthemethod.AllthemethodsinserviceClasswillbeexposedaswebservices.IftheimplementationClassdoesn'timplementanyinterface,theserviceClasselementcanhavetheimplementationClassitselfasitsvalue.services.xmlisplacedwithintheWEB-INF\classes\META-INF\xfiredirectory,sothatthe

XFireruntimecansetuptheserviceenvironment.ThenameandnamespaceelementscanhaveanyvalidXMLnamesasthevalues.

Itisshowninthefollowingcode:

<beans

xmlns="http://xfire.codehaus.org/config/1.0">

<service>

<name>Hello</name>

<namespace>myHello</namespace>

<serviceClass>IHello</serviceClass>

<implementationClass>HelloServiceImpl</implementationClass>

</service>

</beans>

4. web.xml:Themainpartinweb.xmlisconfiguringtheXFireConfigurableServletasshownhere:

<?xmlversion="1.0"encoding="ISO-8859-1"?>

<web-app>

<servlet>

<servlet-name>XFireServlet</servlet-name>

<display-name>XFireServlet</display-name>

<servlet-class>

org.codehaus.xfire.transport.http.XFireConfigurableServlet

</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>XFireServlet</servlet-name>

<url-pattern>/servlet/XFireServlet/*</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>XFireServlet</servlet-name>

<url-pattern>services*</url-pattern>

</servlet-mapping>

</web-app>

AnyrequestofaURLwiththepatternservices*,willberoutedtotheXFireServlet,whichwillinturndothemagicofSOAPhandshaking.

RunningtheSampleAsafirststepandifyouhaven'tdoneitbefore,editexamples.PROPERTIESprovidedalongwiththecodedownloadforthischapter,andchangethepathstheretomatchyourdevelopmentenvironment.Ifyourwebserverdoesn'tincludeXalan(XalanisanXSLTprocessorfortransformingXMLdocuments)libraries,downloadXalanforJava,andtransferxalan*.jarfromthedownloadtothelibrariesfolderofyourwebserver(${tomcat.home}/lib).ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Tobuildthesample,changedirectorytoch05\01_XFireServletWebServiceandexecuteant,asshownhere:

cdch05\01_XFireServletWebService

ant

Thiswillgeneratethewarfile,whichinturncontainsallrequiredlibrariesextractedoutfromtheXFireinstallationfolder.FolderdistwillcontainHelloXFire.war,whichshouldbedeployedinthewebappsfolderofTomcat(oranyotherrelevantwebserver).Now,restarttheserver.

ThewebservicewouldhavebeenexposedbynowandtheservicedefinitioncanbeaccessedusingthefollowingURL:

http://localhost:8080/HelloXFireservicesHe

llo?WSDL

WecannowwriteaClientcodetotestthepreviouswebserviceasshowninthefollowingcode:

publicclassClient

{

privatestaticStringserviceUrl=

"http://localhost:8080/HelloXFireservicesHello";

publicstaticvoidmain(String[]args)throws

Exception

{

if(args.length>0)

{

serviceUrl=args[0];

}

Clientclient=newClient();

client.callWebService("Sowmya"));

}

publicStringcallWebService(Stringname)throws

Exception

{

ServiceserviceModel=new

ObjectServiceFactory().create(IHello.class);

XFirexfire=

XFireFactory.newInstance().getXFire();

XFireProxyFactoryfactory=new

XFireProxyFactory(xfire);

IHelloclient=null;

try

{

client=(IHello)factory.create(serviceModel,

serviceUrl);

}

catch(MalformedURLExceptione)

{

log("WsClient.callWebService():EXCEPTION:"+

e.toString());

}

StringserviceResponse="";

try

{

serviceResponse=client.sayHello(name);

}

catch(Exceptione)

{

log("Client.callWebService():EXCEPTION:"+

e.toString());

serviceResponse=e.toString();

}

returnserviceResponse;

}

}

Attheclientside,weperformthefollowingsteps:

CreateaservicemodelwhichcontainstheservicespecificationfromtheinterfaceIHello.

GetXFireinstanceusingXFireFactory.

RetrieveaproxyfactoryinstanceforXFire.

Usingtheproxyfactory,wecannowgetalocalproxyfortheremotewebserviceusingtheservicemodelandtheserviceendpointURL.

Nowinvoketheremotewebserviceusingtheproxy.

Toruntheclient,assumingthatyouhavealreadycompiledtheclientwhilebuildingthesample,executeantasfollows:

antrun

WebServiceusingXFireSpringXFireExporterHavingseenhowtoexposeaPOJOaswebserviceusingtheXFireclass,org.codehaus.xfire.transport.http.XFireCon

figurableServlet,ournextaimistodothesameusingadifferentapproach.

SampleScenarioHereagain,ouraimistoexposeaPOJOaswebserviceusingXFireSpringsupportclassorg.codehaus.xfire.spring.remoting.XFireEx

porter.Here,theXFireclassXFireExporterisinternallyleveragingSpring'sremotingframeworkandassuchdependsontheSpringlibraries.

CodeListingTheartifactsinthecodelistingisshowninthefollowingfigure:

Wehavefewmoreartifactstobepackagedinthisscenarioandthepackagingtooisslightlydifferentasshownintheabovefigure.Sinceweareusingthesameclasses(IHelloandHelloServiceImpl)asusedinthepreviousexampleheretoo,theyarenotrepeatedhere.Wewilllookattheotherartifactsindetailhere:

1. IHello.class:Thisissameasinthepreviousexample.

2. HelloServiceImpl.class:Thisissameasinthepreviousexample.

3. applicationContext.xml:TheHelloServiceImplclassisconfiguredinSpring'sapplicationContextasshownhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans>

<beanid="helloBean"

class="HelloServiceImpl">

<beans>

4. xfire-servlet.xml:Inxfire-servlet.xml,themainpartistheconfigurationofthewebcontrollerthatexportsthespecifiedservicebeanasanXFireSOAPserviceendpoint.Typically,wewilldothisintheservletcontextconfigurationfile.Asgiveninnextsection,sincethedispatcherservletisnamedxfire,thisfileshouldbecalledxfire-servlet.xml.

Thisisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans>

<beanclass="org.springframework.web.servlet.

handler.SimpleUrlHandlerMapping">

<propertyname="urlMap">

<map>

<entrykey="/HelloService">

<refbean="hello">

<entry>

</map>

</property>

</bean>

<beanid="hello"

class="org.codehaus.xfire.spring.remoting.XFireExporter">

<propertyname="serviceFactory">

<refbean="xfire.serviceFactory">

<property>

<propertyname="xfire">

<refbean="xfire">

<property>

<propertyname="serviceBean">

<refbean="helloBean">

<property>

<propertyname="serviceClass">

<value>IHello</value>

</property>

</bean>

</beans>

1. WehaveconfiguredhelloBeanastheserviceBeanhere.Infact,helloBeaniscomingfromtheapplicationContext.xmlconfiguration.

5. web.xml:Thefeaturetobenotedinweb.xml,istheDispatcherServletconfigurationwhichprovidesthelocationsofwhereyourSpringbeansare.ThecontextConfigLocationtellsSpringwheretofindtheapplicationContext.xmlfiles.

<?xmlversion="1.0"encoding="ISO-8859-1"?>

<web-app>

<context-param>

<param-name>contextConfigLocation</param-name>

<param-value>

WEB-INFapplicationContext.xml

classpath:org/codehaus/xfire/spring/xfire.xml

</param-value>

</context-param>

<listener>

<listener-class>

org.springframework.web.util.Log4jConfigListener

</listener-class>

</listener>

<listener>

<listener-class>

org.springframework.web.context.ContextLoaderListener

</listener-class>

</listener>

<servlet>

<servlet-name>xfire</servlet-name>

<servlet-class>

org.springframework.web.servlet.DispatcherServlet

</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>xfire</servlet-name>

<url-pattern>services*</url-pattern>

</servlet-mapping>

</web-app>

RunningtheSampleTobuildthesample,changedirectorytoch05\02_XFireExportWebServiceandexecuteantasfollows:

cdch05\02_XFireExportWebService

ant

Thiswillgeneratethewarfile,whichinturncontainsallrequiredlibrariesextractedoutfromtheXFireinstallationfolder.FolderdistwillcontainHelloXFireExport.warwhichshouldbedeployedinthewebappsfolderofTomcat(oranyotherrelevantwebserver).Now,restarttheserver.

ThewebservicewouldhavebeenexposedbynowandtheservicedefinitioncanbeaccessedusingthefollowingURL:

http://localhost:8080/HelloXFireExportserv

icesHelloService?WSDL

WecannowwriteaClientsimilartowhatwehaveseeninthepreviousexampletotestthewebservice.

Toruntheclient,assumingthatyouhavealreadycompiledtheClient,whilebuildingthesample,executeantasfollows:

antrun

WebServiceUsingXFireSpringJsr181HandlerJSR181definesanannotatedJavasyntaxforprogrammingwebservicesandisbuiltontheJavaLanguageMetadatatechnology(JSR175).Itprovidesaneasytousesyntaxtodescribewebservicesatthesource-code-levelfortheJ2EEplatform.ItaimstomakeiteasyforaJavadevelopertodevelopserverapplicationsthatconformbothtobasicSOAPandWSDLstandards.Inthissample,wewillincreasethecomplexityofthewebservicebyincludingaTransferObject(TO)asaparameter.WewillalsoseeJSR181annotationsworkbehindthescenestogeneratetheplumbingrequiredtoexposewebservices.

SampleScenarioHereagain,ouraimistoexposeaPOJOaswebserviceanduseJSR181annotationsupportforthis.Boththeserviceinterfaceandtheserviceimplementationwillbeannotated.

CodeListingTheartifactsinthecodelistingisshowninthefollowingfigure:

Wewilllistoutthedifferentartifactswhichmakeupthisexampleinthefollowing:

1. IOrder.class:Thisistheserviceinterfaceandiswebserviceannotated.Sinceallmethodsintheinterfacegetexportedbydefault,youdon'tneedtodefinethe@WebMethodannotationintheinterface.Annotationslike@WebResulttoo,aretotallyoptionalandletyoucontrolhowtheWSDL

lookslike.

Theserviceinterface,IOrder.class,isshowninthefollowingcode:

importjavax.jws.WebService;

importjavax.jws.WebResult;

@WebService

publicinterfaceIOrder

{

@WebResult(name="PurchaseOrderType")

publicPurchaseOrderType

getPurchaseOrderType(StringorderId);

}

2. OrderManagerImpl.class:Asyoucanseehere,OrderManagerImplistheserviceimplementationclassandiswebserviceannotated.Weusethe@WebServiceannotationwithsomeparameterslikewebservicenameasthatisusedontheclient-sidetodecoratetheclassandtellthejsr181processorthatthereisaninterfacetoexportthewebservicemethods.

importjavax.jws.WebService;

@WebService(serviceName="OrderService",

endpointInterface="IOrder")

publicclassOrderManagerImplimplements

IOrder

{

publicPurchaseOrderType

getPurchaseOrderType(StringorderId)

{

PurchaseOrderTypepo=new

PurchaseOrderType();

po.setOrderDate(getDate());

USAddressshipTo=createUSAddress("Binil

Das","23HiddenRange","Dallas",

"TX","17601");

USAddressbillTo=createUSAddress("Binil

Das","29KColonialCreast","Mountville",

"PA","17601");

po.setShipTo(shipTo);

po.setBillTo(billTo);

returnpo;

}

}

1. Itisagainworthnotingtheparameterorreturntypehere,sinceitisnolongersimpleJavatype,butacustomclass(complextype).

3. web.xml:Ifyoucomparethisexamplewiththefirstoneinthischapter,youwillnoticethedifferencehere.InsteadofXFireConfigurableServletwearegoingtouseorg.codehaus.xfire.spring.XFireSpringServletasthecontrollerservlet.Thenyouspecifytheurl-patternsothatsuchpatternURLscanberoutedtoXFireSpringServlet.

<?xmlversion="1.0"encoding="ISO-8859-1"?>

<web-app>

<listener>

<listener-class>

org.springframework.web.context.ContextLoaderListener

</listener-class>

</listener>

<context-param>

<param-name>contextConfigLocation</param-name>

<param-value>

classpath:org/codehaus/xfire/spring/xfire.xml,

WEB-INFclasses/META-INF/xfire/xfire-servlet.xml

</param-value>

</context-param>

<servlet>

<servlet-name>XFireServlet</servlet-name>

<servlet-class>

org.codehaus.xfire.spring.XFireSpringServlet

</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>XFireServlet</servlet-name>

<url-pattern>/servlet/XFireServlet/*</url-pattern>

</servlet-mapping>

<servlet-mapping>

<servlet-name>XFireServlet</servlet-name>

<url-pattern>services*</url-pattern>

</servlet-mapping>

</web-app>

4. xfire-servlet.xml:Next,wehavetodefinetheSpringapplicationContextforXFirecalledxfire-servlet.xml.ThemechanismhereistodefineSpring'sSimpleUrlHandlerMappingwhichinturnmakesuseoftheXFireSpringJsr181HandlerMapping.Oncethatisdone,youonlyneedtodefineyourwebservicePOJOsliketheoneseenwiththeidasannotatedOrder.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans>

<beanid="webAnnotations"

class="org.codehaus.xfire.annotations.

jsr181.Jsr181WebAnnotations"/>

<beanid="handlerMapping"

class="org.codehaus.xfire.spring.

remoting.Jsr181HandlerMapping">

<propertyname="typeMappingRegistry">

<refbean="xfire.typeMappingRegistry">

<property>

<propertyname="xfire">

<refbean="xfire">

<property>

<propertyname="webAnnotations">

<refbean="webAnnotations">

<property>

</bean>

<beanid="annotatedOrder"

class="OrderManagerImpl">

<bean

class="org.springframework.web.servlet.handler.

SimpleUrlHandlerMapping">

<propertyname="urlMap">

<map>

<entrykey="">

<refbean="handlerMapping">

<entry>

</map>

</property>

</bean>

<importresource="

classpath:org/codehaus/xfire/spring/xfire.xml">

<beans>

RunningtheSampleTobuildthesample,changedirectorytoch05\03_XFireJsr181BindWebServiceandexecuteantasfollows:

cdch05\03_XFireJsr181BindWebService

ant

Thiswillgeneratethewarfile,whichinturncontainsallrequiredlibrariesextractedoutfromtheXFireinstallationfolder.FolderdistwillcontainXFireJsr181.war,whichshouldbedeployedinthewebappsfolderofTomcat(oranyotherrelevantwebserver).Now,restarttheserver.

ThewebservicewouldhavebeenexposedbynowandtheservicedefinitionofthesamecanbeaccessedusingthefollowingURL:

http://localhost:8080/XFireJsr181servicesO

rderService?WSDL

WecannowwriteaClientsimilartowhatwehaveseeninthepreviousfewexamplestotestthewebservice.

Toruntheclient,assumingthatyouhavealreadycompiledtheClientwhilebuildingthesample,executeantasfollows:

antrun

XFireExportandBindEJBInChapter4,youhavealreadyseenthesampleofhowtoexposeastatelessEJBservicedeployedinanapplicationserver.Hence,theconsumercanusetheSOAPprotocoltoinvoketheEJBservicethroughaHTTPchannel.Letusagaindoasimilardemonstrationhere,butwithXFirenow.OnceyoucompletethisexampleyouwillbetterappreciatethesimilaritybetweenXFiremechanismsandtheprocessofbinding.

SampleScenarioThescenarioistoexposeanEJBcomponentservicetoexternalclientsthroughaHTTPchannel.ThedifferencebetweentheEJBandSOAPsampleinChapter4(Binding—TheConventionalWay)isthatherewewilluseXFireclassesforservicebinding.Also,thethreeprevioussamplesinthis

chapterhavedemonstratedthepowerofXFireinexposingwebservices.Butthissampleismoretowardsbindinganexternalservice,which,asyouwillseeveryshortly,ismoresimilartothebindingactivitywedousingaJBIstack.

CodeListing

Thecodeforthissampleisorganizedintotwo,intwoseparatefolders,onefortheEJBpartandanotherfortheXFirebinding.Wewillwalkthroughthemainclassesonly,inthefollowing:

1. HelloWorldBI.class:HelloWorldBIistheBusinessInterface(BI)classforthestatelessenterpriseJavasessionbean,henceverysimpleandstraightforward.Thisisdemonstratedasfollows:

publicinterfaceHelloWorldBI

{

StringsayHello(intnum,Strings)throws

IOException;

}

2. HelloWorldEJB.class:HelloWorldEJBistheEJBimplementationclass.

WewillagainuseWeblogiclibrariestomakecodingourEJBsimpler;henceweuseWeblogic'sGenericSessionBeanasthebaseclass,whichwillhavedefaultimplementationsfortheEJBinterface.YoumaywanttodeploytheEJBintoadifferentapplicationserverinwhichcasetweakingthecodeandconfigurationfilesshouldbeatrivialexercise.

Thisisshowninthefollowingcode:

publicclassHelloWorldEJBextends

GenericSessionBean

implementsHelloWorldBI

{

publicStringsayHello(intnum,Strings)

{

System.out.println("sayHellointhe

HelloWorldEJBhas"+"beeninvokedwith

arguments"+s+"and"+num);

StringreturnValue="Thismessagebroughtto

youbythe"+"letter"+s+"andthenumber

"+num;

returnreturnValue;

}

}

3. xfire-servlet.xml:ForreaderswhoarefamiliarwithSpring,xfire-servlet.xmlisselfexplanatorybutfortheinterestofothers,wewillexplainthemainaspects,usingthefollowingcode:.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans>

<import

resource="classpath:org/codehaus/xfire/spring/

xfire.xml">

<beanid="jndiTemplate"

class="org.springframework.jndi.JndiTemplate">

<propertyname="environment">

<props>

<propkey="java.naming.factory.initial">

weblogic.jndi.WLInitialContextFactory

<prop>

<propkey="java.naming.provider.url">

t3://localhost:7001

</prop>

</props>

</property>

</bean>

<beanid="sessionEjbProxy"

class="org.springframework.ejb.access.

SimpleRemoteStatelessSessionProxyFactoryBean">

<propertyname="jndiName">

<value>esb-statelessSession-TraderHome</value>

</property>

<propertyname="jndiTemplate">

<refbean="jndiTemplate">

<property>

<propertyname="resourceRef">

<value>false</value>

</property>

<propertyname="lookupHomeOnStartup">

<value>false</value>

</property>

<propertyname="businessInterface">

<value>

examples.webservices.basic.statelessSession.HelloWorldBI

</value>

</property>

</bean>

<beanid="webService"

class="org.codehaus.xfire.spring.remoting.XFireExporter">

<propertyname="style">

<value>rpc</value>

</property>

<propertyname="use">

<value>encoded</value>

</property>

<propertyname="serviceFactory">

<refbean="xfire.serviceFactory">

<property>

<propertyname="xfire">

<refbean="xfire">

<property>

<propertyname="serviceBean">

<refbean="sessionEjbProxy">

<property>

<propertyname="serviceInterface">

<value>

examples.webservices.basic.

statelessSession.HelloWorldBI

</value>

</property>

</bean>

<bean

class="org.springframework.web.servlet.handler.

SimpleUrlHandlerMapping">

EJB-XFiresampleclasses<property

name="urlMap">

<map>

<entrykey="/InvokeService">

<refbean="webService">

<entry>

</map>

</property>

</bean>

</beans>

xfire-servlet.xmldefinestheSpringapplicationContextforXFire.ThefirstpartisdefiningajndiTemplatepointingtheapplicationservercontext.jndiTemplateprovidesmethodstolookupandbindobjects.Weareusingweblogic.jndi.WLInitialContextFactoryhere,butthisneedstobechangedtosuityourapplicationserverenvironment.SinceourEJBisaremotestatelesssessionbean,wecanusetheSpringprovidedSimpleRemoteStatelessSessionProxyFactoryBeanclassforproducingproxiestolookupandaccessservices.

ThejndiTemplatepropertysuppliesdetailstolookupwhereasthebusinessInterfacepropertyspecifiesthebusinessinterface

implementedbytheservice.ThismuchisenoughtogetahandleontheremoteserviceandthenextpartistoexporttheservicefromwithintheXFirecontext,whichwecandousingtheXFireSpringXFireExporter.NexttheSimpleUrlHandlerMappingwillrouteanyrequestsofURLpattern,/InvokeService,totheaboveexportedservice.

4. web.xml:web.xmlisasshowninthefollowingcode,whichisagainsimilartothatinthepreviousexample.

<?xmlversion="1.0"encoding="ISO-8859-1"?>

<web-app>

<context-param>

<param-name>contextConfigLocation</param-name>

<param-value>WEB-INFxfire-servlet.xml

classpath:org/codehaus/xfire/spring/xfire.xml

</param-value>

</context-param>

<listener>

<listener-class>

org.springframework.web.util.Log4jConfigListener

</listener-class>

</listener>

<listener>

<listener-class>

org.springframework.web.context.ContextLoaderListener

</listener-class>

</listener>

<servlet>

<servlet-name>xfire</servlet-name>

<servlet-class>

org.springframework.web.servlet.DispatcherServlet

</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>xfire</servlet-name>

<url-pattern>services*</url-pattern>

</servlet-mapping>

</web-app>

5. build.xml:Thebuild.xmlrequiresspecialattentioninthiscasebecauseweexplicitlyrefertotheEJBclientjar.WegeneratethisasapartoftheEJBbuildprocessandlater,duringXFireexport,weincludethisclientjartooalongwiththewarfileastheXFireruntimerequiresthebusinessinterface,home,andremotestubsofEJB,andothersimilarhelperclassesduringserviceinvocation.

Thebuild.xmlisshownasfollows:

<targetname="copyjars">

<copytodir="${tomcat.home}/lib">

<fileset

dir="${bea.home}/weblogic812/server/lib">

<includename="weblogic.jar">

<fileset>

</copy>

<copytodir="${build.dir}WEB-INFlib">

<fileset

dir="${bea.home}/weblogic812/samples/server/

examples/build/clientclasses">

<includename="${ejb.client.jar}">

<fileset>

</copy>

</target>

RunningtheSampleRunningthesampleinvolvesmultiplestepsthatarelistedasfollows:

DeployingtheEJB:TodeploytheEJB,wehavetofollowgeneralEJBdeploymentstepsasspecifiedinWeblogicdocumentation.

First,changedirectorytotheEJBsamplesdirectoryasshownhere:

cdch05\04_XFireExportAndBindEjb\ejb

NowsettheenvironmentvariablesforthebuildconsoleaspertheWeblogicdocumentationandthenusetheantscriptprovidedalongwiththeWeblogicserverbundle.Forthat,dothefollowing:

%wl.home%\samples\domains\examples\setExample

sEnv.bat

%wl.home%\server\bin\ant

WecaneventestwhetherourEJBdeploymentwentfinebyexecutingatestclient,asshownhere:

%wl.home%\server\bin\antrun

XFireexportandBindEJB:Inthisstep,wecreatethewebapplicationin.warformatanddeployitinthewebserver.Changedirectorytoch05\04_XFireExportAndBindEjb\XFireBindandexecuteanttobuildthewebapplication,asshownhere:

cdch05\04_XFireExportAndBindEjb\XFireBind

ant

Thiswillgeneratethewarfile,whichinturncontainsallrequiredlibrariesextractedoutfromtheXFireinstallationfolder.FolderdistwillcontainXFireBindEjb.war,whichshouldbedeployedinthewebappsfolderofTomcat(oranyotherrelevantwebserver).Now,restarttheserver.

ThewebservicewouldhavebeenexposedbynowandtheservicedefinitioncanbeaccessedusingthefollowingURL:

http://localhost:8080/XFireBindEjbservices

InvokeService?WSDL

WecannowwriteaClientsimilartowhatwehaveseeninthepreviousfewexamplestotestthewebservice.

Toruntheclient,assumingthatyouhavealreadycompiledtheclient,whilebuildingthesample,executeantasfollows:

antrun

XFireforLightweightIntegrationAlmostallliteraturethatwehavebeenreadingaboutXFire,isfordeployingandaccessingwebserviceinalightweightmanner.SincethistextisspeakingonSOI,weareinterestedintheSOIaspectsofXFire.Wehavedemonstratedthisthroughtheexamplesinthischapter.Later,whenwelookattheServiceMixexamples,wewillseetherealpowerofXFire,especiallytheXFireProxyclasses.

SummaryWebservicesprovideuswithameanstoattainSOA-basedarchitectures.Withthegrowingnumberoftechnologyframeworksavailabletoday,itiseasytodeploywebservices.

XFireisaSOAPstackwithwhichwecanquicklyandeasilyexposewebservices.Asseeninthischapter,acombinationof

technologystackslikeXFireandSpringcanhelptobindexternalservices,includingexternalEJBservices.Oncebound,theseservicescanbere-publishedaswebservicessothattheybecomefirewallfriendly.ThisissimilartoJBIbindingofservicesprovidingamediationlayerforserviceintegration,moreofwhichwewillseeinlaterchapters.

WenowhavehadenoughoftraditionalbindingsandbindingsusingXFire.WiththisbackgrounditistimenowtodelvedeepintoJBIandrelatedservices.WewillcontinuewithmoreJBIdiscussionsinthenextchapterbyunderstandingtheJBIpackaginganddeploymentmodel.

Chapter6.JBIPackagingandDeploymentSmallthingsmatter;whetherpackaginganddeploymentaresmallerconcernscomparedtodesignanddevelopment,isstillunderdispute.However,onethingisclear,thatastandardwayofpackaginganddeploymentpromotescross-platformandcross-vendorportabilityofcomponents,whetheritisourfamiliar.jar,.war,and.rarfilesorthenewJBIarchivedefinedbytheJBIspecification.

ServiceMixisacontainerforJBIcomponents.AtthesametimetheServiceMixJBIcontainerbyitselfisaJBIcomponent.ThischaracteristicenablesServiceMixtobedeployedasastandardJBIcomponentintoanothervendor'sESBcontainer,providedthehostESBcontainersupportsJBIcomponents.Thisissimilartoajava.awt.Framewhichisacomponentthatyoucanincludeinacontainer.Atthesametime,theFramebyitselfisacontainerwhichcancontainothercomponents.ServiceMixisanalogoustoourFrameexample.

WhenwesayaServiceMixcontainerisaJBIcomponent,itmeansthatahostcontainer(likeOpenESBfromSun)canmakeuseofalmosteveryServiceMixcomponent,whetherthecomponentisastandardJBIcomponentoralightweightcomponent(thedifferencebetweenthesetwoisexplained

later).Thepromiseofthismodelisthatthedeveloper-createdServiceMixcomponentscanbereusedinanyotherJBIcontainer.

ThischapterdealswiththedetailsofhowwepackageanddeployJBIcomponentsintoServiceMix.Wewilllookintothefollowing:

Installation,serviceassembly,andserviceunitpackaging

StandardversuslightweightJBIcomponentsinServiceMix

Apackaginganddeploymentsample

PackaginginServiceMixServiceMix,beingJBI-compliant,followstheJBIpackagingschema.JBIspecificationdefinesstandardpackagingforbothinstallationofcomponentsanddeploymentofartifactstothosecomponentsthatfunctionascontainersforothercomponents.

InstallationPackagingJBItalksabouttwotypesofJBIcomponentsforinstallation—aJBIcomponentandashared-libraryforusebysuchcomponents.TheJBIinstallationpackageisaZIParchivefile.ThisZIParchivehascontentsthatareopaquetoJBIexceptforthesocalledinstallationdescriptorthatmustbenamedandlocatedasfollows:

META-INFjbi.xml

Thejbi.xmlmustconformtoeitherthecomponentinstallationdescriptorschemaortheshared-libraryinstallationdescriptorschema.Asampleinstallationdescriptorisshowninthefollowingcode:

<?xmlversion="1.0"encoding="utf-8"?>

<jbiversion="1.0"

xmlns="http://java.sun.com/xml/ns/jbi"

xmlns:sam="http://www.binildas.com/esb/sample">

<componenttype="service-engine">

<identification>

<name>sample-engine-1</name>

<description>Anexampleservice

engine</description>

<sam:TypeInfopart-number="012AB490-578F-114FAA">

BPEL:2.0:XQuery:1.0:XPath:2.0:XPath:1.0

</sam:TypeInfo>

</identification>

<component-class-namedescription="sam">

com.binildas.esb.Sample1

</component-class-name>

<component-classpath>

<path-element>Sample1.jar</path-element>

</component-classpath>

<bootstrap-class-name>

com.binildas.esb.Sample1Bootstrap

</bootstrap-class-name>

<bootstrap-classpath>

<path-element>Sample1.jar</path-element>

</bootstrap-classpath>

<shared-library>slib1</shared-library>

<sam:Configurationversion="1.0">

<sam:ThreadPoolsize="10">

<sam:Queue1size="50">

</sam:Configuration>

</component>

</jbi>

Thejbi.xmlcanincludeextensionelements.IfyouobservethesampledescriptorabovetherearetwoextensionelementsnestedbetweentheConfigurationelements.Theseextensionelementsprovidecomponentspecificinformation,usinganXMLnamespacethatisoutsidethatofdocumentelements(http://www.binildas.com/esb/sampleinourcase).TheyareThreadPoolandQueue1.JBIimplementationsandcomponentimplementationsmayusetheseextensionelementstoprovideextra,componentspecificinformationfortheuseofthecomponent,componenttooling,orboth.Forexample,youcanthinkofanIDEwhichwillhelpinJBIdevelopmentanddeployment,usingwhichyoucanconfigurethecharacteristicsoftheextensionelements(likethenumberofthreadsinthepool,inoursample).

ServiceAssemblyPackagingAServiceAssembly(SA)deploymentpackagecontainsopaque(toJBI)deploymentartifacts,andadeploymentdescriptor.Thisdeploymentdescriptorisnamedjbi.xmlandprovidesinformationfortheJBIdeploymentservicetoprocessthecontentsofthedeploymentpackappropriately.TheSAthencontainsoneormoreServiceUnit(SU)archives,allcontainedwithinaZIParchivefile.AsampledeploymentdescriptorreferringtotwoSUsisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<jbixmlns="http://java.sun.com/xml/ns/jbi"

version="1.0">

<service-assembly>

<service-assembly>

<identification>

<name>soap-demo</name>

<description>Soapdemo</description>

</identification>

<service-unit>

<identification>

<name>engine-su</name>

<description>Containstheservice</description>

</identification>

<target>

<artifacts-zip>engine-su.zip</artifacts-zip>

<component-name>servicemix-jsr181</component-

name>

</target>

</service-unit>

<service-unit>

<identification>

<name>binding-su</name>

<description>Containsthebinding</description>

</identification>

<target>

<artifacts-zip>binding-su.zip</artifacts-zip>

<component-name>servicemix-http</component-name>

</target>

</service-unit>

</service-assembly>

</jbi>

ThisdeploymentdescriptorreferstotwodifferentSUsnamelyengine-suandbinding-su.ThesetwoSUarchives,plusthedescriptoritself,arecombinedintoasingleZIParchivetoformtheSA.ThedeploymentdescriptorisplacedinsidetheZIParchiveinadirectorystructureasgiveninthefollowing,whichwillbeexplainedwithfigureslaterinthischapter:

META-INFjbi.xml

ServiceUnitPackagingTheSAcontainsopaque(toJBI)deploymentartifactscalledSUs,whichareagainZIParchivefiles.ThesearchivescontainasingleJBI-defineddescriptorfile:

META-INFjbi.xml

Thejbi.xmldescriptorprovidesinformationabouttheservices,whicharestaticallyprovidedandconsumedasaresultofdeployingtheSUtoitstargetcomponent.

TheServiceMixJBIcontaineralsosupportsXBean-baseddeployment—wecandeploySUscontainingafilenamedxbean.xml.Since,atSA-level,theSUsareopaquetoJBIdeployment,eventheSAcontainingXBean-basedSUscanbeportedacrossJBIcontainers.

DeploymentinServiceMixJBIcomponents,bythemselves,canactasJBIcontainers.Addingmoreartifactstoinstalledcomponentsiscalleddeployment.ServiceMixsupportstwomodesofdeployment—standardandJBIcomplaint,andlightweight.

StandardandJBIcompliantUsingthismode,wecaninstallcomponentsatruntimeanddeploySAsontothem.ThesecomponentsareJBI

specificationcompliantandhencetheyareJBIcontainersforothercomponentstoo.TheycanacceptSAdeploymentsandareimplementedusingtheservicemix-commonmodule.SincetheyareJBIcompliant,theyarepackagedasZIParchivefileswithajbi.xmldescriptor.

ExamplesofafewServiceMixstandardJBIcomponentsareshowninthefollowinglist:

servicemix-jsr181

servicemix-drools

servicemix-http

servicemix-jms

Wecanalsoconfiguretheabovementionedstandardcomponents,tobeusedinastaticdeploymentmodeusingtheservicemix.xmlconfigurationfile.

Wecandeploylightweightcomponentsinthismode.Todothat,lightweightcomponentsmustbedeployedtotheservicemix-lwcontainer.

LightweightLightweightcomponentsarePOJOcomponentsimplementingtherequiredJBIinterfaces.Theydon'tfollowstandardJBIpackaging;hence,donotsupportSUdeployments.Duetothisreason,theycannotnormallybedeployedatruntime.Incaseweneedtodeploythematruntime,wecandeploythemontheservicemix-lwcontainer(lightweightcontainer).

LightweightcomponentsnormallyinherittheComponentSupportclassdirectlyorindirectly,andaremainlyintheservicemix-componentsmodule.Wenormallyusetheservicemix.xmlstaticconfigurationfilewhenwewanttorunasingleapplicationfortestingpurposes,orwhenweembedServiceMixinawebapplication,forexample.

AFewexamplesareshowninthefollowinglist:

JDBCcomponent

Quartzcomponent

XSLTcomponent

PackagingandDeploymentSampleWewillnowcreateSUsandSAs,anddeploythemintotheServiceMixJBIcontainer.Thewholeprocesscanbedividedintotwophases,withmultiplestepsineachphase.

Thetwophasesintheprocessarethefollowing:

Componentdevelopment

Componentpackaging

PhaseOne—ComponentDevelopment

Thisphaseincludescodingandbuildingthecodebase.Wehavethecodebasesplitupintomultiplefolderseachrepresentingseparateartifacts,whichgointothefinalSAsasshowninthefollowingfigure.

Thecomponentsfolderissupposedtocontainlightweight(orPOJO)components,butinourcase,wehaveasimpleserviceclass(HelloServicePojo)implementingaBI(HelloServiceBI),thisisshowninthefollowingcode:

publicinterfaceHelloServiceBI

{

Stringhello(Stringphrase);

Stringhello(Stringphrase);

}

publicclassHelloServicePojoimplements

HelloServiceBI

{

privatestaticlongtimes=0;

publicStringhello(Stringphrase)

{

System.out.println("HelloServiceBean.hello{"+

(++times)+"}...");

return"FromHelloServiceBean:HELLO!!Youjust

said:"+phrase;

}

}

PhaseTwo—ComponentPackagingWewillnowhavetwoServiceUnits—oneaSEandtheotheraBC.BoththeseServiceUnitswillbepackagedintoasingleServiceAssemblysothatwecandeploythemintotheESB.Theservicemix-sharedServiceAssemblyprovidescommonservicesandhencewewillalsodeploythattoointotheESB.Thefullsetupisasshowninthefollowingfigure:

WewillnowlookintothepackagingofindividualSUsandSAs.

Theengine-su(ServiceEngineServiceUnit)isbasedonxbean.xml,whichleveragesjsr181:endpointtoexposeourserviceclassasawebservice.Thisisshowninthefollowingcode:

<?xmlversion="1.0"?>

<beans

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:demo="http://binildas.com/esb/sample">

<classpath>

<location>.</location>

</classpath>

<jsr181:endpoint

pojoClass="samples.HelloServicePojo"

annotations="none"service="demo:hello-service"

endpoint="hello-service"

serviceInterface="samples.HelloServiceBI">

<beans>

Thebinding-su(BindingComponentServiceUnit)isalsobasedonxbean.xml,whichleverageshttp:endpointintheconsumer(consumertoNMR)role.Thisisshowninthefollowingcode:

<?xmlversion="1.0"?>

<beans

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:demo="http://binildas.com/esb/sample">

<http:endpointservice="demo:hello-service"

endpoint="hello-service"role="consumer"

locationURI="http://localhost:8192/Service/"

defaultMep="http://www.w3.org/2004/08/wsdl/in-out"

soap="true">

<beans>

ThetwoServiceUnitscanbenowpackagedintoasingleServiceAssembly.So,thesetwoSUsareconfiguredinthe.xmlfileshownasfollows:

META-INFjbi.xml

Thecontentsofjbi.xmlfileareasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<jbixmlns="http://java.sun.com/xml/ns/jbi"

version="1.0">

<service-assembly>

<identification>

<name>soap-demo</name>

<description>Soapdemo</description>

</identification>

<service-unit>

<identification>

<name>engine-su</name>

<description>Containstheservice</description>

<description>Containstheservice</description>

</identification>

<target>

<artifacts-zip>engine-su.zip</artifacts-zip>

<component-name>servicemix-jsr181</component-

name>

</target>

</service-unit>

<service-unit>

<identification>

<name>binding-su</name>

<description>Containsthebinding</description>

</identification>

<target>

<artifacts-zip>binding-su.zip</artifacts-zip>

<component-name>servicemix-http</component-name>

</target>

</service-unit>

</service-assembly>

</jbi>

Asisevident,theServiceAssemblyencapsulatestwoServiceUnits—engine-suandbinding-su.

Thus,theServiceUnitisaZIParchivethatwillcontainyourapplication'sJavaclassfilesandtheservicemix.xmlconfigurationfile.TheServiceUnitcanalsocontainajbi.xmlfilewhichprovidesinformationaboutservicesstaticallyprovidedandconsumed.ThenameoftheZIParchivethatwecreatehereislaterreferredtofromthejbi.xmlfileoftheenclosingServiceAssembly.

Buildingandpackagingcanbeautomatedusingtheantbuildtoolwiththehelpofbuild.xml,showninthefollowingcode:

<projectname="jms-binding"default="setup"

basedir=".">

<targetname="build-components"depends="init">

<javacsrcdir="${comp.src.dir}"

destdir="${comp.build.dir}">

<classpathrefid="javac.classpath">

<javac>

</target>

<targetname="build-engine-su"

depends="build-components">

<zipdestfile="${build.dir}/engine-su.zip">

<filesetdir="${comp.build.dir}"/>

<filesetdir="${su.engine.src.dir}">

<zip>

</target>

<targetname="build-binding-su">

<zipdestfile="${build.dir}/binding-su.zip">

<filesetdir="${su.binding.src.dir}">

<zip>

</target>

<targetname="build-sa"

depends="build-engine-su,build-binding-su">

<zipdestfile="${build.dir}/soap-demo-sa.zip">

<filesetdir="${build.dir}"

includes="engine-su.zip">

<filesetdir="${build.dir}"

includes="binding-su.zip">

<filesetdir="${sa.src.dir}">

<zip>

</target>

<targetname="setup"depends="build-sa">

<mkdirdir="${install.dir}">

<mkdirdir="${deploy.dir}">

<copytodir="${install.dir}">

<filesetdir="${servicemix.home}/components"

includes="jsr181">

<filesetdir="${servicemix.home}components"

includes="http">

<filesetdir="${servicemix.home}components"

includes="servicemix-shared">

<copy>

<copyfile="${build.dir}/soap-demo-sa.zip"

todir="${deploy.dir}">

<target>

</project>

Inthesetuptargetwecanseethatwecopythejsr181component,httpcomponent,andservicemix-sharedfromtheServiceMixinstallationpathtoourtargetinstalldirectory.ThesearestandardJBIcomponentsontowhichwearedeployingtheSUartifacts.Whenwedothat,ifServiceMixisalreadyrunning,itwilldetectthefilepresentthereandstartit.

RunningthePackagingandDeploymentSampleAsafirststepandifyouhaven'tdoneitbefore,editexamples.PROPERTIESprovidedalongwiththecodedownloadforthischapterandchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Nowweneedtobuildthesamples.Forthis,changedirectorytoch06\SoapBindingandthenexecuteant,asshownhere:

cdch06\SoapBinding

ant

Thiswillbuildtheentiresample.

Nowwearegoingtorunthisexampleasstandalone.Thatis,ServiceMixwillbestartedandthentheSOAPdemoisdeployedandrun.Thisisdonebyexecutingtheservicemix.xmlfilefoundinthetopmostfolder(ch06\SoapBinding).

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.

config.PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<sm:containerid="jbi"rootDir="./wdir"

installationDirPath="./install"

deploymentDirPath="./deploy"flowName="seda">

<sm:activationSpecs>

</sm:activationSpecs>

</sm:container>

</beans>

WecanbringupServiceMixbyrunningthefollowingcommands:

cdch06\SoapBinding

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

WhenwestartServiceMix,theJBIcontainerisconfiguredusingtheaboveservicemix.xmlfile.

Torunthedemo,thereisaClient.htmlfileprovidedagaininthetopfolder.TheClientwillsendthefollowingrequest:

<SOAP-ENV:Envelopexmlns:SOAP-ENV=

"http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-

instance"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<SOAP-ENV:Body>

<ns1:hello

xmlns:ns1="http://binildas.com/esb/sample"SOAP-

ENV:encodingStyle=

"http://schemas.xmlsoap.org/soap/encoding/">

<phrasexsi:type="xsd:string">what&apos;syour

name?

</phrase>

</ns1:hello>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

TheclientsendstheaboveSOAPrequesttohttp://localhost:8192/Service/.As,wealreadyconfiguredServiceMixhttp:endpointlisteninginport8192,theSOAPrequestwillbeinterceptedandsenttotheJBINMR.http:endpointhastheconsumerrolewhenitsendsaSOAPrequesttotheNMRanditwillberoutedto

http:endpointlisteninginport8192.ThisserviceistheJSR181bindingcomponentforourserviceimplementationclass,whichwheninvokedwillcarryoutthebusinessfunctionalityandanyresponseisreturnedthroughasimilarchannelbacktotheclient.

SummaryWeusemultiplearchiveformatsforvariousJ2EEcomponents—.jar,.war,.ear,and.rararefewamongstthem.Now,JBIspecificationrecognizes.zipasavalidarchiveformatforJBIcomponents.SUsandSAsarepackagedasvalid.zipfilesandaredeployedintoJBIcompliantcontainers.Inthischapter,wehaveseenhowtowritecodefromscratch,packageitintostandardJBIformats,anddeployittotheESBruntime.Wewillfollowsimilarpackagingformostofoursamplesinthesubsequentchapters.

ThenextchapterwillteachhowtocustomcodeJBIcomponentsonourown,sothattheycantakepartinthemessageexchangeshappeningthroughtheJBIbus.

Chapter7.DevelopingJBIComponentsUntillnow,youhavebeenassemblingJBIcomponentswhicharepre-builtandavailablealongwiththeServiceMixinstallationinyourownway.TheaimofthischapteristogetstartedindevelopingyourowncomponentsanddeployingthemintotheServiceMixJBIcontainer.Inthischapter,wewillvisitthecoreAPIfromServiceMixaswellasfromtheJBIspecification,whichwillfunctionasusefulhelperclassesusinglightweightcomponents.WewillalsocreateourownJBIcomponentanddeployitintotheJBIbus.

DevelopingJBIcomponentsinServiceMixrequiresthedevelopertowriteabitofplumbingcode,whichmayormaynotbesoappealing.Tomakethedeveloper'slifeeasy,ServiceMixsupportsSpring-basedPOJOclassesandtheirconfiguration.ServiceMixalsoprovidesmanycomponenthelperclasses.Itisuptothedeveloperwhethertomakeuseofthesehelperclasses,ordeveloptheirowncomponentsorcodeagainstthecoreAPIsofServiceMixandJBI,thoughthereisnoreasonwhyanyoneshouldn'tbeusingthehelperclasses.

So,wewillcoverthefollowinginthischapter:

NeedforcustomJBIcomponents

ServiceMixcomponenthelperclasses

Create,deploy,andrunJBIcomponents

Buildandrunasample

NeedforCustomJBIComponentsWehavealreadyseenmanyServiceMixcomponents,bothJBIcompliantandlightweight.ManyofthemareavailableinsidethecomponentsfolderintheServiceMixinstallation.Anaturalqueryinthiscontextis"WhydoesoneneedtodevelopcustomcomponentsinServiceMix?".OftenIseemyselfasalazyprogrammer,tryingtoreusecodes,components,orservicesratherthanhandcodethemeverytime.

Goingbythattrend,IamalsocompelledtolookatServiceMixwithanaimtoreuseanythingandeverything,andnottohandcodeanything.Thepropositionlooksfine,butthetruthisthattheworldisnotidealallthetime.Inanidealworld,wewillhavealltheServiceMixcomponents,tools,andhooksavailable,sothatwecanassembleorreconfigurethecomponentstosuitourneeds.Thismakessenseinapureintegrationinitiativewhereweonlyintegrate,anddonotdevelopanything—afterall,JBIandServiceMixisallaboutintegration.However,sincetheworldisfarfromidealandallofuswillhaveourownintegrationproblemsandscenarios.Often,wewillhavetocustomcodeintegrationwrappers,messageorchestrationlogic,orerrorhandlinglogic.ThislogiccanbecodedintocomponentscreatedoutofServiceMixhelperclassesandeasilydeployedintoaServiceMix

container.

ServiceMixComponentHelperClassesServiceMixprovidesalotofplumbingcodeintheformofreusablecomponenthelperclasses.Mostoftheseclassesareabstractbaseclassesfromwhichthedevelopercanderivetheirownclassestoputcustomlogic.Themainclassesofinterestandtheirrelationshipareshowninthefollowingfigure:

MessageExchangeListenerMessageExchangeListenerisaServiceMixpackageinterface,verysimilartotheJMSMessageListener.Thisinterfaceisshowninthefollowingcode:

packageorg.apache.servicemix;

importjavax.jbi.messaging.MessageExchange;

importjavax.jbi.messaging.MessagingException;

publicinterfaceMessageExchangeListener

{

/**

MessageExchangepasseddirectlytothelistener

insteadofbeingqueued

@paramexchange@throwsMessagingException

/

publicvoidonMessageExchange(MessageExchange

exchange)throwsMessagingException;

}

Whenourcustomcomponentsimplementthisinterface,wewillbeabletoreceivenewmessageexchangeseasily,ratherthanwritinganewthread.ThedefaultJBIasynchronousdispatchmodeliswhereathreadisusedperJBIcomponentbythecontainer.However,whenthecomponentimplementtheMessageExchangeListenerinterface,theServiceMixcontainerwilldetecttheuseofthisinterfaceandbeabletoperformimmediatedispatch.

TransformComponentSupportTransformComponentSupportcontainsadefault

implementationfortheonMessageExchangemethod.Thecodeismoreexplanatorythanatextualdescriptionofthesequences.Hence,let'sreproducethatinthefollowingcode:

publicvoidonMessageExchange(MessageExchange

exchange)

{

if(exchange.getStatus()==ExchangeStatus.DONE)

{

return;

}

elseif(exchange.getStatus()==

ExchangeStatus.ERROR)

{

return;

}

try

{

InOnlyoutExchange=null;

NormalizedMessagein=getInMessage(exchange);

NormalizedMessageout;

if(isInAndOut(exchange))

{

out=exchange.createMessage();

}

else

{

outExchange=

getExchangeFactory().createInOnlyExchange();

out=outExchange.createMessage();

}

booleantxSync=exchange.isTransacted()&&

Boolean.TRUE.

equals(exchange.getProperty(JbiConstants.SEND_SYNC));

copyPropertiesAndAttachments(exchange,in,out);

if(transform(exchange,in,out))

{

if(isInAndOut(exchange))

{

exchange.setMessage(out,"out");

if(txSync)

{

getDeliveryChannel().sendSync(exchange);

}

else

{

getDeliveryChannel().send(exchange);

}

}

else

{

outExchange.setMessage(out,"in");

if(txSync)

{

getDeliveryChannel().sendSync(outExchange);

}

else

{

getDeliveryChannel().send(outExchange);

}

exchange.setStatus(ExchangeStatus.DONE);

getDeliveryChannel().send(exchange);

}

}

else

{

exchange.setStatus(ExchangeStatus.DONE);

getDeliveryChannel().send(exchange);

}

}

catch(Exceptione)

{

try

{

fail(exchange,e);

}

catch(Exceptione2)

{

logger.warn("Unabletohandleerror:"+e2,e2);

if(logger.isDebugEnabled())

{

logger.debug("Originalerror:"+e,e);

}

}

}

}

Theabovecodecallstransform(exchange,in,out).Bydoingso,itisinvokingtheabstractmethodinTransformComponentSupport.Theabstractmethodisreproducedasfollows:

protectedabstractboolean

transform(MessageExchangeexchange,

NormalizedMessagein,NormalizedMessageout)

throwsException;

Hence,itiseasytojustimplementthetransformmethodinthecustomcodeandletthehelperclassworksbehindthescenesforallmessageexchanges.

ComponentSupportandPojoSupportaretheothertwohelperclassesinthehierarchy.

Create,Deploy,andRunJBIComponentThissectioncoversfromendtoend,thecreation,deployment,andrunningofasampleJBIcomponentinServiceMix.

Followingthebasicsdemonstratedinthischapter,readerscancodeJBIcomponentstosuittheirownrequirements.Wewillalsoseemanysuchcomponentsintheexamplesincomingchapters.Thecodeforthissampleiskeptinch07\CustomComponentfolder.

CodeHttpInterceptorComponentHttpInterceptor,asthenameimplies,willinterceptmessagescomingintheHTTPchannel.Itthenprintsoutthemessagetotheconsole,andsendssomemessagebackthroughtheresponsechannel.Toquicklycodeourcomponent,wewillextendtheServiceMixcomponenthelperclassnamelyTransformComponentSupport.

Thisisdemonstratedinthefollowingcode:

publicclassHttpInterceptorextends

TransformComponentSupport

{

publicHttpInterceptor(){}

protectedbooleantransform(MessageExchange

exchange,NormalizedMessagein,NormalizedMessage

out)throwsMessagingException

{

NormalizedMessagecopyMessage=

exchange.createMessage();

getMessageTransformer().transform(exchange,in,

copyMessage);

Sourcecontent=copyMessage.getContent();

System.out.println("HttpInterceptor.transform02.

content="+content);

StringcontentString=null;

if(contentinstanceofDOMSource)

{

contentString=XMLUtil.node2XML(((DOMSource)

content).getNode());

System.out.println("HttpInterceptor.transform03.

contentString="+contentString);

}

out.setContent(newStringSource("<?xml

version=\"1.0\"encoding=\"UTF-8\"?>

<Response>ResponseFromServer</Response>"));

returntrue;

}

}

Aswedescribedearlier,wewillimplementtheabstracttransformmethodinTransformComponentSupport.TheTransformmethodwillhaveareferencetotheMessageExchangeandalsototheinandoutNormalizedMessages.Wefirstcopythecontentsfrom

theinmessageandprintthatouttotheconsole.Then,wecreateanewStringSourcewithsomemessagefromtheserver,sendingthattotheoutNormalizedMessages.Thecodeisassimpleasthat,sincemostoftheplumbinghasalreadybeendoneforyoubythebaseclassmethods.

ConfigureHttpInterceptorComponentAs,wecanconfiguretheHttpInterceptorcomponentasSU,wewilldotheconfigurationofthiscomponentasaSUintheservicemix.xmlfilekeptatch07\CustomComponent\su\servicemix.xml.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:demo="http://www.binildas.com/esb/customcomponent">

<classpath>

<location>.</location>

</classpath>

<sm:serviceunitid="jbi">

<sm:activationSpecs>

<sm:activationSpeccomponentName="interceptor"

endpoint="interceptor"

service="demo:interceptor">

<sm:component>

<beanclass=

"com.binildas.esb.customcomponent.HttpInterceptor">

<sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:serviceunit>

</beans>

ThisisdifferentfromtheXBean-basedpackagingexample,thatwesawinthepreviousexample.As,weareusingservicemix.xmltospecifytheSU.Thus,wecanseethattherearemultiplewaysbywhichwecanconfigureandpackageourSUs.

PackageHttpInterceptorComponentInChapter6,wesawhowtopackageanddeploycomponentsinServiceMix.Wewillfollowthesamepackagingmethodologyhere.WewillcreateanSUandthenpackageitintoanSA.

WehavealreadyseentheSUconfiguration,letusnowlookintotheSAconfigurationasfollows:

\sa\META-INF\jbi.xml

ThecontentoftheJbi.xmlfileisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<jbixmlns="http://java.sun.com/xml/ns/jbi"

version="1.0">

<service-assembly>

<identification>

<name>InterceptorAssembly</name>

<name>InterceptorAssembly</name>

<description>InterceptorService

Assembly</description>

</identification>

<serviceunit>

<identification>

<name>Interceptor</name>

<description>InterceptorService

Unit</description>

</identification>

<target>

<artifacts-zip>Interceptor-su.zip</artifacts-zip>

<component-name>servicemix-

lwcontainer</component-name>

</target>

</serviceunit>

</service-assembly>

</jbi>

Here,wepackagetheInterceptorServiceUnitintotheSA.ThemainpointtobenotedintheSAjbi.xmlisthetargetelementoftheserviceunit.Here,wespecifythattheSUartifact(thatis,Interceptor-su.zip)istobedeployedintotheservicemix-lwcontainertargetcontainer.

DeployHttpInterceptorComponentTodeploytheHttpInterceptorcomponent,wehaveaservicemix.xmlfileinthetopmostfoldertostarttheServiceMixcontainer.

Thecontentoftheservicemix.xmlfileisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:demo="http://www.binildas.com/esb/customcomponent">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<sm:containerid="jbi"rootDir="./wdir"

installationDirPath="./install"

deploymentDirPath="./deploy"flowName="seda"

monitorInstallationDirectory="true"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpeccomponentName="httpReceiver"

service="bt:httpBinding"endpoint="httpReceiver"

destinationService="demo:interceptor">

<sm:component>

<beanclass="org.apache.servicemix.components.

http.HttpConnector">

<propertyname="host"value="127.0.0.1"/>

<propertyname="port"value="8912">

<bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

Thefirstthingtonotehereisthatwehave

installationDirPath="./install"fortheJBIcontainer.ThisiswhereweplaceourJBIcomponents,whicharetobeinstalledbyServiceMix.Hence,theycanactascontainersforcomponentslikeourHttpInterceptor.

ItisalsoworthnotingthatwehaveanHttpConnectorconfiguredwithoursample,andHttpInterceptor,asthedestinationServicesothatwehaveawaytotestoursampletoo.

BuildandRuntheSampleAsafirststepandifyouhaven'tdoneitbefore,editexamples.PROPERTIESprovidedalongwiththecodedownloadforthischapterandchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Thebuild.xmlisasusualbutwewilllistthemajordifferenceshere.

As,wewantHttpInterceptorSUtobedeployedintoservicemix-lwcontainerwhilebuildingthecodebase,wewillalsocopytheservicemix-lwcontainerfromServiceMixinstallationtoinstallationDirPath.

<copytodir="${install.dir}"overwrite="true">

<filesetdir="${servicemix.home}/components"

includes="lwcontainer">

<filesetdir="${servicemix.home}components"

includes="shared">

<copy>

Executeanttobuildthesampleasshownasfollows:

cdch07\CustomComponent

ant

WecanbringupServiceMixbyrunningthefollowingcommands:

cdch07\CustomComponent

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

WhenwestartServiceMix,theJBIcontainerisconfiguredusingtheaboveservicemix.xmlfile.Torunthedemo,thereisaClient.htmlfileprovidedagaininthetopfolder.

SummaryInthischapter,welookedatthecoreAPIfromServiceMixaswellasfromtheJBIspecification,whichwillfunctionasusefulhelperclassesusingwhichwecandeveloplightweightcomponentsquickly.

WehavealsocustomcodedaJBIcomponentanddeployeditintotheJBIbus.Youmaynotwanttoalwayscustomcodecomponents.Manytimes,JBIcomponentswillbeavailableasoff-the-shelf-libraries.Suchcomponentscantakepartinthe

messageexchangesthroughtheESBandcanprovideintegrationwithexternalserviceslikeCICSandCORBA,forexample.IfbyanychanceyouwanttocreateyourownJBIcomponents,thenyoucanfollowtheguidelinespresentedinthischapterasastartingpoint.

AswehavecoveredthestandardJBIpackaginganddeploymentmodelinChapter6,wenowhaveenoughtoolsetstodelvedeepintoJBIandESB.WewillcontinueourjourneybylookingatusingSpringbeanstoSpring-wrapanEJBserviceontotheJBIbusinthenextchapter.Bydoingso,wewillexposeEJBasaWSDLcompliantserviceacrossfirewalls—yesreally,wearegoingtodothat!Hence,don'tscrapyourexistinginvestmentsinEJBtillyoucoverthenextchapter.

Chapter8.BindingEJBinaJBIContainerEJBisthedistributedcomponentparadigmintheJava-J2EEworld.EJBprovednottobeapushbuttonsolutionforprogrammingproblems.Still,afewofthepromises(ofcourse,realitytoo)—distributedtransactionpropagation,component-baseddeploymentmodel,andinterface-baseddesign,provedtobereallyuseful.Today,wehavebeentalkingaboutlightweightcontainersandaspect-basedprogramming,andwhetherEJBstillholdsthecrownissomethingwhichhastobeansweredonacasebycasebasis.BeingneitheraproponentnoranopponentofEJB,onethingIhavetoadmitisthattheindustryhasalotinvestedinthistechnology.Scrapingalltheseinvestmentsandimplementingalternatesolutionsissurelynotatopicforourdiscussion,atleastinthistextbook.ForourSOI-baseddiscussion,perhaps,itismoreinterestingtolookathowtoreusethoseexistinginvestments.Hence,wecancontinuebuildingnewersystembasedonhigherlevelsofSOA,maturitycoexistingwitholdfunctionality.Inclearerterms,coexistingservicesandcomponents.

Wewillcoverthefollowinginthischapter:

Componentversusservices.

Indiscriminationatconsumerperspective.

StepwisebindingEJBsample.

ReconcilingEJBresources.

ComponentversusServicesInachapterlikethis,itmakessensetodiscussthedifferencebetweencomponentsandservices.

Componentsarefirst-classdeployableunitspackagedintostandardartifacts.Componentsliveinsomecontainer;thereiscomponent-containerinteractionforcomponentlifecyclemanagementandeventnotification.Thus,componentsarephysicalunits.Componentswillalsoassumeexplicitlyabouttheprotocolandformatofdatasentoverthewire,sincemostofthetimetheyaretechnology-dependent.

ServicesontheotherhandhaveURLaddressablefunctionality,accessibleoverthenetwork.Atleastfromtheconsumerperspective,therearenolifecycleactivitiesassociatedwiththeservice,sinceservicesarestatelessandidempotent.Betweenanytwoserviceinvocations,thereisnostatemaintainedattheprovider-level(ofcourse,therearestatefulservicestoo).Thusservicesarevirtualdistributedcomponents,whichareneutralabouttheprotocolandformatofsendingmessages.Byneutral,wemeanitdoesn'tmatterwhattheunderlyingtechnologyorplatformisaslongastheproviderandconsumeragreestoacommonprotocolandformat.

CoexistingEJBComponentswith

ServicesWeneedtodeviseamechanismbywhichwecanallowcoexistenceofcomponentsandservices.Bycoexistence,wemeanaconsumershouldbeabletoconsumeawebserviceandanEJBservicewithoutanydifference.Traditionalcomponentdevelopers,whoalsoknowhowtodevelopawebservice,willfirstwonderhowthiscanbepossible.Bothhavecompletelydifferentconsumptionmechanisms—awebserviceischaracter-orientedwhereasanEJBserviceisbinary-oriented,justoneofthemanymismatches.

ESBBindingComponents(BC)comestotherescue.ByjudiciouscombinationofBCs,evenanEJBcomponentcanbehookedtotheNMRsothatanyconsumer,whethertheyareinadifferenttechnologylike.NETorMainframe,caninteroperate.Ofcourse,thisisnotsomethingnew,sincewehavebeendoingthisforyearsusingCORBAorCOBOLCopyBooks,butneverinastandardway.NowJBIpromisesthesamesothatinteroperabilityofourcomponentsacrossmultipleJBIcontainersisnolongeradream.

Theadvantageofthiskindofinteroperabilityismultifold.First,evenanorganizationwithlessSOAmaturityimplementationscanquickstarttheirenterpriseefforts,andwhentheydosotheycanreuseexistingITassets.ThisisdifferentfromtheBing-Bangapproach,whichwillreducetheoverallriskconsiderably.Secondly,developerswillbereadytoacceptthechangesincechangeisnotabrupt—changewillstillharmonizetheirpastintellectualspendingintermsoftimeandeffortfordevelopingallthosepast(EJB)components.

IndiscriminationatConsumerPerspectiveWhenwewanttocoexistcomponentsandservicestogether,technicalindiscriminationisveryimportant.Asaconsumercannowusethesamesetoftoolsandmethodologiestoaccessfunctionality,whetheritisa(web)serviceoranEJBcomponent.IfyouhaveprogrammedanEJBorwebservicebefore,youwillagreethatthecontractmodelsaredifferent.InthecaseofanEJB,theconsumer-providercontractistheEJBhomeandEJBremoteinterface(betteristhecasewiththeCORBAworld,wheretheinterfaceistheIDL).Moreover,theseinterfacesdon'tmakeanysensetoanyconsumerwhodoesn'tspeakJava.However,inawebservicethecontractistheWSDL,whichissupposedtobeinterpretedbyanyconsumer.Toindiscriminate,wewillneedtoprovidethesameinterfaceasthewebserviceandseehoweasyitistodowiththehelpofanESB.

BindingEJBSampleWewillnotspendtoomuchtimedescribinghowtowriteanddeployanEJBcomponent,sincetherearealotofbooksandresourcesavailablewhichwilldojustthat.However,wewillspendsometimelookingathowwecanuseSpringbeanstoSpring-wrapanEJBservice.MoretimewillbespentonactualbindingofEJBandrelateddiscussion.Asusual,wewilldothissampleinastepbystepmanner.

StepOne—DefineandDeploytheEJBServiceTheEJBserviceweimplementisverysimple;theclassesandinterfacesinvolvedareshowninthefollowingfigure:

WeneedtoabstractouttheinterfacefromallEJBspecificdetails;hence,wehavefollowedtheBIpatterntodefinetheinterface.HelloServiceBIistheBI,whichisvoidofanyEJBspecificAPI.

packagesamples;

publicinterfaceHelloServiceBI

{

Stringhello(Stringphrase)throws

java.io.IOException;

}

Asafirststepandifyouhaven'tdoneitbefore,edit

examples.PROPERTIESprovidedalongwiththecodedownloadforthischapterandchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Forthesampledeployment,wewilluseBEAWeblogicserver'sexampledomain.Hence,allnecessarydeploymentdescriptorsfortheWeblogicEJBcontainerareprovidedintherespectivefolders.IncaseyouneedtodeploytheEJBintoadifferentvendor'sEJBcontainer,changethedeploymentdescriptorsaccordingly.

Executethefollowingscriptsinthecommandprompttobringuptheserverfirst:

cd

%BEA_HOME%/weblogic812/samples/domains/examples

%BEA_HOME%/weblogic812/samples/domains/examples/s

tartExamplesServer

TobuildanddeploytheEJB,inadifferentcommandpromptchangedirectoryto:

ch08\BindEjb\01_Ejb

%BEA_HOME%/weblogic812/samples/domains/examples/s

etExamplesEnv

%BEA_HOME%/weblogic812/server/bin/ant

Thiswillbuild,package,anddeploytheEJBmoduleintotheWeblogicserver.Itwillalsocreateaclientjarcontainingall

theclient-sidestubs,whichisrequiredlaterforaccessingtheservice.Incaseyouneedtotestwhetheryourdeploymentwentfine,thereisaclientprovidedwhichyoucanexecutebytypingthefollowingcode:

ch08\BindEjb\01_Ejb

antrun

StepTwo—BindEJBtoServiceMixOncetheEJBserviceisupandrunning,wenowwanttoexposetheserviceacrossfirewallsinatechnologyneutralformatandprotocol.Bydoingso,wecanmaketheEJBserviceconsumablebyotherB2Bpartners.ThedeploymentdiagramforanESB-basedsolutionforthesamplescenarioisshowninthefollowingfigure:

Here,theApplicationServerwillhostourEJBcomponentservices.TheESBserver(cluster)infrontoftheApplicationServerwillhosttherequiredBCstoproxytheEJBservicebehindthescenesasfirewall-friendlyservices,consumablebyotherB2Bclients.

InChapter6,youhavealreadyseenhowwecanleveragethe

servicemix-jsr181standardJBIcomponentasacontainerforcustomPOJOclasses,sothatthemethodsdefinedinaPOJOareexposedasservices.WeneedtofollowasimilarapproachtobindanEJBservicetoototheJBIbus,buttheconfigurationisslightlydifferent.Thesamplebindingscenarioinsidethebusisrepresentedinthefollowingfigure:

LetusnowbindtheEJBservicetotheJBIbususingtheservicemix-jsr181component.servicemix-jsr181canbeconfiguredinthelightweightmodetoo.Letuslookintotheservicemix.xmlfileforthat,asshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:my="http://binildas.com/esb/bindejb">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<sm:containerid="jbi"useMBeanServer="true"

createMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<http:component>

<http:endpoints>

<http:endpointservice="my:HelloServiceBIService"

endpoint="HelloServiceBI"role="consumer"

defaultOperation="hello"

targetService="my:jsrEjbEP"

targetEndpoint="jsrEjbEP"

locationURI="http://localhost:8192/Services/

HelloWebService"soap="true"

defaultMep="http://www.w3.org/2004/08/wsdl/

in-out">

<http:endpoints>

</http:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="jsrEjbBC"

service="my:jsrEjbBC"endpoint="jsrEjbBC">

<sm:component>

<jsr181:component>

<jsr181:endpoints>

<jsr181:endpointannotations="none"

service="my:jsrEjbEP"endpoint="jsrEjbEP"

serviceInterface="samples.HelloServiceBI">

<jsr181:pojo>

<beanclass="org.springframework.ejb.

access.SimpleRemoteStatelessSession

ProxyFactoryBean">

<propertyname="jndiName"value=

"sample-statelessSession-TraderHome">

<propertyname="businessInterface"

value="samples.HelloServiceBI">

<propertyname="jndiTemplate">

<refbean="jndiTemplate">

<property>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

</jsr181:endpoints>

</jsr181:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="jndiTemplate"

class="org.springframework.jndi.JndiTemplate">

<propertyname="environment">

<props>

<propkey="java.naming.factory.initial">

weblogic.jndi.WLInitialContextFactory

</prop>

<propkey="java.naming.provider.url">

t3://localhost:7001

</prop>

</props>

</property>

</bean>

</beans>

Wewillnowdiscussthiscodesectionbysection.

JNDIcontextisthestartingpointingettingareferencetoanEJBresource.Inthepreviousstep,wehavedeployedourEJBservicetotheWeblogicserver.ToaccessWebLogic'sJNDItree,youneedtoestablishastandardJNDIInitialContextrepresentingthecontextrootoftheserver'sdirectoryservice.Forthis,thePROVIDER_URLpropertyspecifiestheURLoftheserver,whoseJNDItreewewanttoaccessandtheINITIAL_CONTEXT_FACTORYpropertycontainsthefullyqualifiedclassnameofWebLogic'scontextfactory.

IfyouneedtoaccessWebLogic'sJNDItree,itisadvisedtoestablishthecontextusingtheclassnameweblogic.jndi.WLInitialContextFactory,sothatwecanusetheWeblogicspecifict3protocolwhichisoptimizedforaccessingservices.Wedefinethesedetailsbyconfiguringtheorg.springframework.jndi.JndiTemplate

bean.

ThenextstepistodefineourPOJOclass.ThePOJOclasshereisnotaserviceclass,butaclient-sideproxytotheremoteEJBservice.There'salotofbackendplumbinghappeningherewhenweuseSimpleRemoteStatelessSessionProxyFactoryBe

an,courtesyoftheSpringAOPframework.ThePOJObeandefinitioncreatesaproxyfortheremotestatelessEJB,whichimplementsthebusinessmethodinterface.TheEJBremotehomeiscachedonstartup,sothere'sonlyasingleJNDIlookup.EachtimetheEJBisinvoked,theproxyinvokesthecorrespondingbusinessmethodontheEJB.AllthecontextdetailsnecessaryforcontactingtheserverareretrievedfromthepreviousjndiTemplatebean.

OnceourPOJObeanisready,itisjustamatterofwrappingthatupintheservicemix-jsr181asshownintheconfigurationabove.Whenyouconfigurethejsr181:endpoint,youcanalsospecifytheserviceInterface.Thiswillholdtheclassnameoftheinterfacetoexposeasaserviceandthisabstractionwillhelpthebindingtobeexposedinstandardways(usingWSDL),whichwewillexploreshortly.

WewillappreciatethefactthatEJBcomponentsareremotable,buttheynormallyexposebinaryinterfaces.Binaryprotocolsarenotplatformagonistic,noraretheyfirewall-friendly.Hence,EJBcomponentsarenormallypreferredonaLANwherewehaveperfectcontrolofthenetwork,sothatnothinghindersmarshallingbytesacrossdomains.Ifwehavetomakethemfirewall-friendly,wecantunnelthemthroughadifferentprotocol,whichbyitselfisfirewall-friendly.Weblogicandothersimilarserversprovideeasytunnelingoptionsbutstillthemechanismisnotastandardapproach.ThesecondmethodistowrapEJBwithwebservices.Thisisalsomadeeasynowadaysbyapplicationservers,itisjustamatterofenablingoptionsduringdeploymenttime.

WhenwehaveanESB,anoptionavailabletousistoleveragetheprotocolorformatconversioncapabilityoftheESBtomakeEJBinvocationsfirewall-friendly.ServiceMixservicemix-httpisexactlywhatweneedhere.Byconnectingaservicemix-httpchannelinserialandinfrontoftheservicemix-jsr181,wecanmaketheEJBcomponentserviceavailableoutsidethefirewallasanormalwebservice!Whatmore,wecanevenrunourentirenormalwebservicesclienttoolkittoretrieveWSDL,andthentogenerateclient-sideproxyclassessothatitiseasytoinvokefunctionality.ThetargetServiceandthetargetEndpointattributesofservicemix-httppointbacktotherespectivenamesoftheservicemix-jsr181,sothatweconnectthecomponentstogether.

StepThree—DeployandInvokeEJBBindinginServiceMixForthissamplewewillfollowthelightweightdeploymentmodel.

ch08\BindEjb\02_BindInEsbcontainsallthenecessaryfilesforbinding,building,anddeployingtheartifactsintoaServiceMixcontainer.TobuildtheESBbindingcodebaseanddeploythesample,changedirectorytoch08\BindEjb\02_BindInEsb,whichcontainsatop-levelbuild.xmlfile.Thenotablesectioninthebuild.xmlisshowninthefollowingcode:

<targetname="copy-components"depends="init"

description="Buildcomponents">

<copytodir="${servicemix.home}/lib/optional"

overwrite="true">

<filesetdir="${client.classes.dir}"

includes="sample_statelessSession_client.jar">

<copy>

<copytodir="${servicemix.home}/lib/optional"

overwrite="true">

<filesetdir="${wl.home}/server/lib"

includes="weblogic.jar">

<copy>

</target>

Here,wefirstcopytheEJBclientjarfromtheWeblogicdirectorytoServiceMix'soptionallibraryfolder.Otherthanthis,wedon'thaveanyexplicitreferraltoEJBclassesintheServiceMixbindingabove.Whatyou'reseeingisSpring'ssuccessinabstractingawaytheclientsideoftheclunkyEJB

contract.However,thehomeandremoteinterfacesarestillrequired—Springisusingthemunderthehood,justasyouwouldifyouhadtowritetheJNDIlookup,EJBhome,andcreatecallsyourself.WhatSpringisdoingbehindthescenesismakingaJNDIlookupforthehome,thencallingthecreate()methodonthehomeandenablingyoutoworkwiththat.ThatiswhywerequiretheEJBclientjarintheclasspath.

Wehaveseenpreviously,howweconfiguredjndiTemplatebyexplicitlyreferringtheweblogic.jndi.WLInitialContextFactory.Thisisincludedinweblogic.jarandhenceweincludethatjarintheServiceMix'soptionallibraryfoldertoo.IncaseyouareusingadifferentEJBserverandyouuseadifferentjava.naming.factory.initialclass,thenincludetherespectivejarsinServiceMix'soptionallibraryfoldertoo.Tobuild,executeantasshowninthefollowingcode:

cdch08\BindEjb\02_BindInEsb

ant

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder.

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

TheClient.htmlfileprovidedagaininthesamefoldercanbeusedtosendmessagestotestthedeployedservice.

StepFour—AccessWSDLandGenerateAxis-basedStubstoAccessEJBOutsideFirewallAsdiscussedabove,wecannowaccesstheWSDLauto-generatedbyServiceMixoutoftheearlierEJBbinding.TheWSDLcanbeaccessedbypointingyourbrowsertothefollowingURL:

http://localhost:8192/Services/HelloWebSer

vice/?wsdl

or

http://localhost:8192/Services/HelloWebSer

vice/main.wsdl

TheWSDLisreproducedinthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

xmlns:ns1="http://io.java"

xmlns:soap11="http://schemas.xmlsoap.org/soap/

envelope/"

xmlns:soap12="http://www.w3.org/2003/05/

soap-envelope"

xmlns:soapenc11="http://schemas.xmlsoap.org/soap/

encoding/"

xmlns:soapenc12="http://www.w3.org/2003/05/

soap-encoding"

xmlns:tns="http://binildas.com/esb/bindejb"

xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/

soap/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

targetNamespace="http://binildas.com/esb/bindejb">

<wsdl:types>

<xsd:schemaattributeFormDefault="qualified"

elementFormDefault="qualified"

targetNamespace="http://io.java"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:complexTypename="IOException">

<xsd:schema>

<xsd:schemaattributeFormDefault="qualified"

elementFormDefault="qualified"

targetNamespace="http://binildas.com/esb/bindejb"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:elementname="hello">

<xsd:complexType>

<xsd:sequence>

<xsd:elementmaxOccurs="1"minOccurs="1"

name="in0"nillable="true"type="xsd:string">

<xsd:sequence>

</xsd:complexType>

</xsd:element>

<xsd:elementname="helloResponse">

<xsd:complexType>

<xsd:sequence>

<xsd:elementmaxOccurs="1"minOccurs="1"

name="out"nillable="true"type="xsd:string">

<xsd:sequence>

</xsd:complexType>

</xsd:element>

<xsd:elementname="IOException"

type="ns1:IOException">

<xsd:schema>

</wsdl:types>

<wsdl:messagename="helloResponse">

<wsdl:partelement="tns:helloResponse"

name="parameters">

</wsdl:part>

</wsdl:message>

<wsdl:messagename="IOException">

<wsdl:partelement="tns:IOException"

name="IOException">

</wsdl:part>

</wsdl:message>

<wsdl:messagename="helloRequest">

<wsdl:partelement="tns:hello"name="parameters">

</wsdl:part>

</wsdl:message>

<wsdl:portTypename="jsrEjbEPPortType">

<wsdl:operationname="hello">

<wsdl:inputmessage="tns:helloRequest"

name="helloRequest">

</wsdl:input>

<wsdl:outputmessage="tns:helloResponse"

name="helloResponse">

</wsdl:output>

<wsdl:faultmessage="tns:IOException"

name="IOException">

</wsdl:fault>

</wsdl:operation>

</wsdl:portType>

<wsdl:bindingname="HelloServiceBIBinding"

type="tns:jsrEjbEPPortType">

<wsdlsoap:bindingstyle="document"

transport="http://schemas.xmlsoap.org/soap/

http">

<wsdl:operationname="hello">

<wsdlsoap:operationsoapAction="">

<wsdl:inputname="helloRequest">

<wsdlsoap:bodyuse="literal">

<wsdl:input>

<wsdl:outputname="helloResponse">

<wsdlsoap:bodyuse="literal">

<wsdl:output>

<wsdl:faultname="IOException">

<wsdlsoap:faultname="IOException"use="literal">

<wsdl:fault>

</wsdl:operation>

</wsdl:binding>

<wsdl:servicename="HelloServiceBIService">

<wsdl:portbinding="tns:HelloServiceBIBinding"

name="HelloServiceBI">

<wsdlsoap:address

location="http://localhost:8192/Services/

HelloWebService/">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

WewillnowuseApacheAxistoolstoauto-generateclient-sidestubsandbindingclassesusingwhichwecanwriteasimpleJavaclientclass,toaccesstheservicethroughtheHTTPchannel.Whenwedothis,theinterestingpointisthatweareaccessinganEJBservicebehindthescenes,butusingtheSOAPformatforrequestandresponse,thattoothroughafirewall-friendlyHTTPchannel.TheAxisclientclassesareplacedinthedirectorych08\BindEjb\03_AxisClient.

Todothat,wehavetousethewsdl2javaanttask.Letusfirstdeclarethetaskdefinitionandexecutethattasktogeneratestubclasses,asshowninthefollowingcode:

<taskdefname="wsdl2java"

classname="org.apache.axis.tools.ant.wsdl.Wsdl2javaAntTask"

loaderref="axis">

<classpathrefid="classpath">

<taskdef>

<targetname="wsdl2java">

<javaclassname="org.apache.axis.wsdl.WSDL2Java"

fork="true"

failonerror="true">

<argvalue="-o">

<argvalue="${src}">

<argvalue="-x">

<argvalue="http:/io.java">

<argvalue="HelloWebService.wsdl">

<classpath>

<pathrefid="classpath"/>

<pathelementlocation="${build}">

<classpath>

</java>

</target>

ThetaskwillextractthedetailsfromtheWSDLandgeneratethefollowingclient-sideartifactsinthech08\BindEjb\03_AxisClient\srcfolder:

com\binildas\esb\bindejb\HelloServiceBIBindingStub.java

com\binildas\esb\bindejb\HelloServiceBIService.java

com\binildas\esb\bindejb\HelloServiceBIServiceLocator.java

com\binildas\esb\bindejb\JsrEjbEPPortType.java

RememberthattheaboveWSDLfromwheretheAxistoolgeneratedtheclient-sideartifactsis,infact,theWSDLretrievedfromtheServiceMixESB.TheClientjavaclasscanbewrittenagainstthesegeneratedfilesasfollows:

publicclassClient

{

privatestaticStringwsdlUrl=

"http://localhost:8192/

Services/HelloWebService/main.wsdl";

privatestaticStringnamespaceURI=

"http://binildas.com/esb/bindejb";

privatestaticStringlocalPart=

"HelloServiceBIService";

protectedvoidexecuteClient(String[]args)throws

Exception

Exception

{

HelloServiceBIServicehelloServiceBIService=

null;

JsrEjbEPPortTypejsrEjbEPPortType=null;

if(args.length==3)

{

helloServiceBIService=new

HelloServiceBIServiceLocator(args[0],new

QName(args[1],args[2]));

}

else

{

helloServiceBIService=new

HelloServiceBIServiceLocator(wsdlUrl,new

QName(namespaceURI,localPart));

}

jsrEjbEPPortType=

helloServiceBIService.getHelloServiceBI();

log("ResponseFromServer:"+

jsrEjbEPPortType.hello("Binil"));

}

publicstaticvoidmain(String[]args)throws

Exception

{

Clientclient=newClient();

client.executeClient(args);

}

}

TobuildtheentireAxisclientcodebase,assumingthatboththeEJBserverandtheServiceMixcontainerisupandrunning,changedirectorytoch08\BindEjb\03_AxisClient,whichcontainsatop-levelbuild.xmlfile.Executeantasshowninthefollowingcommands:

cdch08\BindEjb\03_AxisClient

ant

ThiswillgeneratetherequiredAxisclient-sidestubsandcompiletheclientclasses.Nowtoruntheclient,executethefollowingcommand:

antrun

ReconcilingEJBResourcesThischapterdemonstratedhowtoengineerwithServiceMix,hencewecanconsiderEJBcomponentservicesequivalenttonormalwebservicessothesamerulescanbeappliedfromaconsumerperspective.Thiswillhavegreaterimpactintoday'ssolutioninfrastructure.Thisisbecauseinthelastonedecadeorso,wesawtheriseofEJBcomponent-basedprogramming.Settingaside(if)anydrawbacks,EJBgaveusalotofsupportforcrosscuttingconcernsliketransactionmanagementandinstancepooling.Forthesamereason,lotsofsolutionartifactsarestillavailableandremaininghostedintheformofEJBservices.UsinganESB,wearenolongerforcedtothrowawayallthoseinvestments,insteadleveragetheminaservicesecosystemenvironment.IamsureIwillhaveaneasytimeconvincingmyCTOthatIdon'tneedtoscrapallmyEJBinvestments,insteadIcanreusetheminthebestpossiblemanner.Ihopeyouwillalsoenjoythesame.

SummaryESBasaservicefabricsupportsintegratingmultipleservicesandcomponenttypes.Hence,fromtheconsumerperspective,theyseeapureservicesinterfacewithallSOAqualities.ThischapterdemonstratedhowthesameprincipleshelpedustoexposeanEJBserviceasafirewall-friendlywebservice.ThenotablethinghereistheeasewithwhichanESBframeworkdoesthis—andthatiswheretherighttoolswillhelptosolveevennontrivialproblemseasily.So,insteadofholdingtheESBhammerandlookingateveryITproblemasanail,useESBandJBItosolveappropriateintegrationproblemsfollowingSOIguidelinesalone.MostcomponentframeworksavailabletodayallowevenPOJOcomponentstobeexposedasservicessothattheycanbeconsumedremotely.ThisisalightweightapproachcomparedtothetraditionalEJBprogrammingparadigm.

Inthenextchapter,wewilllookintothisconcepttounderstandhowwecanexposeanannotatedPOJOasservicesintheESB.

Chapter9.POJOBindingUsingJSR181Firstthingsfirstandsimplethingsforemost!IshouldhaveintroducedthePOJObindingasthefirstexampleduetothesimplicityinthename"POJO".However,thereisanothercomponentassociatedwiththePOJObinding,whichistheservicemix-jsr181componentthatweneedtolearntogether.ThisiswhywedelayedthePOJObindinguntilnow.Wecannowmoveon.

Wewillcoverthefollowinginthischapter:

OverviewonPOJO

JSR181andservicemix-jsr181component

APOJObindingsampledemonstratingPOJOasservices

AsecondsampletodemonstrateaccessingtheJBIbusdirectlyatprogrammingAPI-level

POJOChristopherRichardsoninhiscoverstory"WhatIsPOJOProgramming"says:

Fortunately,there'snowamuchbetterwaytobuildEnterpriseJavaapplications:PlainOldJavaObjects(POJOs),which

areclassesthatdon'timplementinfrastructureframework-specificinterfaces,andnon-invasiveframeworkssuchasSpring,Hibernate,JDO,andEJB3,whichprovideservicesforPOJO.

WhatarePOJOsPOJOsdependonbasicorcoreJavaanddon'timplementanyotherAPI's.Theyneithercontainanyframeworkspecificcallbackmethods,nordependonanyexternalmethods,whichtheyneedtocall.Instead,anythird-partyframeworkcanmakeuseofaPOJOclassandexposeitorutilizeitintheirownway.Forexample,anO-RmappingframeworkcanuseaPOJOmodelclassandpersistinarelationaldatabase.Similarly,aservicegenerationframeworkcanexposeallthepublicmethodsinaPOJOserviceclassasservices.ATOassemblercangetandsetvaluesfromaPOJOTOtocreateacoarsergrained,POJOTOgraph.

ComparingPOJOwithotherComponentsPOJOs,beingsignificantlylightweight,willhavetheirownadvantagesanddisadvantageswhencomparedtoothercounterpartcomponentssuchasEJBsandservlets.

ThemainadvantageisthatthePOJOscanbedeployedandruninthesimplestoftheJavaruntimesavailable,andnothingpreventsyoufromdeployingthemintoafull-fledged

containerinfrastructure.Thiswillhelpyoutoleveragethebestofboththeworlds—thelightweightdeploymentmodelandthefull-fledgedcontainerinfrastructurefunctionalities.

Atthesametime,thedownsideofPOJOsisthattheyarenotremotable.Remotingisthemechanismbywhichfunctionalitycanbeaccessedfromaremotenode,throughanetwork.EJB,servlet,andJSP.Thesecomponentsareinherentlyremotable.HowinterestedwouldareaderbeifwecouldmakeaPOJOremotable—withoutmuchhassle?Holdon,wewilldothatinthischapter.

ServiceMixservicemix-jsr181ServiceMix'sservicemix-jsr181componentisbuiltbasedontheJSR181specification.

JSR181JSR181definesanannotatedJavasyntaxforprogrammingwebservicesandisbuiltontheJavaLanguageMetadatatechnology(JSR175),toprovideaneasywaytousesyntaxtodescribewebservicesatthesource-code-levelfortheJ2EEplatform.ItaimstomakeiteasyforaJavadevelopertodeveloptheserverapplicationsthatconformbothtobasicSOAPandWSDLstandards.TheWSMfortheJavaplatformisbuiltupontheJSR175andhencerequiresaJDKinstallationsupportingJavametadata.

servicemix-jsr181servicemix-jsr181componentisaJBIstandardSE.ItcanexposeannotatedPOJOasservices.servicemix-jsr181internallyusesXFiretoexposePOJOsasservices.servicemix-jsr181linkstheJBIchanneltoXFiretransportusingthefollowingsteps:

servicemix-jsr181firstcreatesaDefaultXFireandregisterstheJbiTransporttothetransportmanagerofXFire.

ThenitusesXFire'sObjectServiceFactorytocreateanXFireservice.

servicemix-jsr181thenconfigurestheserviceandregistersitintheXFireserviceregistry.

TheabovestepslinktheJBIchanneltoXFiretransport.However,allthesearethebackgroundplumbingabstractedoutbytheservicemix-jsr181,sothatthedeveloperwon'tseeallthesecomplexities.WehavealreadydiscussedthepowerofXFireandworkedoutafewsamples.AgainwewillleverageXFire,butnowintheformofastandardJBIcomponentitself,forbinding.

AspertheServiceMixdocumentation,servicemix-jsr181supportsthefollowingfeatures:

noannotations

jsr181annotations

commons-attributesannotations

aegisbinding

jaxb2binding

xmlbeansbinding

wsdlautogeneration

MTOMorattachmentssupport

servicemix-jsr181DeploymentXBean-baseddeploymentcanbeusedtodeployservicemix-jsr181,bothintheproviderandconsumerroles.

Thefirststepistodeclarethenecessaryjsr181namespaceelements,shownasfollows:

<beans

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:test="http://binildas.com/esb/jsrpojo">

</beans>

WhetheritisasimplePOJObindingoranEJBbinding,weneedtoincludealltherequiredinterfaceandimplementationclassestotherespectiveclasspaths.WecandothisbyincludingtherequiredclassfilesorjararchivesintheSUandreferencethemusingthefollowingtagsinthexbean.xmlconfigurationfile:

<classpath>

<location>.</location>

</classpath>

ThepathvaluespecifiedforthelocationtagisrelativetotheunzippedSU.Forexample,ifJsrBindistheSUname

andwehaveaclasscalledtest.EchoService,thenweneedtopackagetheclasswithinthefoldertest,relativetothetop-levelofJsrBindarchive.Similarly,youcanalsoaddJavaarchives(.jar)containingclassfilesbyexplicitlyspecifyingthemasfollows:

<classpath>

<location>lib/test.jar</location>

</classpath>

servicemix-jsr181Endpointservicemix-jsr181endpointscanbeconfiguredinmultipleformatsusingSpringbeanconfigurations.Themultipleformatsarelistedinthefollowinglist:

1. <jsr181:endpointannotations="none"service="test:helloService">

<jsr181:pojo>

<beanclass="samples.HelloServicePojo">

</bean>

</jsr181:pojo>

</jsr181:endpoint>

2. <beanid="helloPojo"class="samples.HelloServicePojo"/>

<jsr181:endpointpojo="#helloPojo"/>

3. <jsr181:endpointpojoClass="samples.HelloServicePojo"annotations="none"/>

POJOBindingSampleFromtheentirediscussionwehavehadinthischapter,letusbuildaPOJObindingsample.Thecodebaseforthesampleislocatedinthefolderch09\Jsr181BindPojo.

SampleUseCaseInthisPOJObindingsampleusecase,wewillintegratePOJOcomponentswithServiceMixJBIcomponentssothattheywilltakepartinmessageexchangeswiththeNMR.ThePOJOclassusedinthesamplecanbereplacedwithyourcodeperformingtransformation,dependinguponyourbusinessscenario.Inoursamplehere,wewilluseasetofcomponentsintegratedintheESBasshowninthefollowingfigure:

AsimplePOJOclassaloneisenoughtodemonstratethebindingsample.However,wewillalsoexposePOJOasanormalwebservice,accessWSDL(yes,really),andrunanAxisclientagainsttheWSDLtogenerateclientstubstoaccessthePOJOserviceremotely.Tofacilitateallthis,wewillfirstintegrateourPOJOclass(HelloServicePojo)withaservicemix-jsr181component.Nowasweknow,HTTPisaneasyandsimplechanneltoaccessservices.Hence,letusalsointegrateaservicemix-httpintheconsumerroletotheNMRsothatourtestclientscanhaveaneasychanneltosendmessages.Thecomponentsareintegratedasshownintheabovefigure.Whentheclientsendsamessage,

themessage-flowacrosstheNMRthroughvariousJBIcomponentsaremarkedbynumbersinsequence.

POJOCodeListingLetusfirstdefineaBI.NotethattheBIisnotmandatoryforPOJObinding,buthereweareusingbest(interface-basedprogramming)practices.Thus,HelloServiceBIistheBI.

TheinterfaceHelloServiceBIisshowninthefollowingcode:

publicinterfaceHelloServiceBI

{

Stringhello(Stringphrase)throws

java.io.IOException;

}

InJavaRMIorEJBprogramming,thebusinessmethodsareusuallymarkedtothrowajava.rmi.RemoteException.WecangeneralizethisexceptionscenariobyreplacingtheRemoteExceptionwiththejava.io.IOException.WewillfollowthisconventionbymarkingourbusinessmethodsasthrowingIOException.Thereisabsolutelynothingwrongifwedon'tmentiontheexceptioninthethrowsclausetoo,foroursampleshere.Now,HelloServicePojowillimplementtheaboveinterface.Moreoverasyoucansee,thisclassqualifiestobeahundredpercentPOJOclass.

TheHelloServicePojoclassisshownasfollows:

publicclassHelloServicePojoimplements

HelloServiceBI

{

privatestaticlongtimes=0;

publicStringhello(Stringphrase)

{

System.out.println("HelloServiceBean.hello{"+

(++times)+"}");

return"FromHelloServiceBean:HELLO!!Youjust

said:"+phrase;

}

}

XBean-basedPOJOBindingUsingXBean,wewillnowconfigurethePOJOtobedeployedontothestandardservicemix-jsr181JBIcomponent.

Thexbean.xmlisasshowninthefollowingcode:

<beans

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:test="http://binildas.com/esb/jsrpojo">

<classpath>

<location>.</location>

</classpath>

<jsr181:endpointannotations="none"

service="test:helloService"

serviceInterface="samples.HelloServiceBI">

<jsr181:pojo>

<beanclass="samples.HelloServicePojo">

</bean>

</jsr181:pojo>

</jsr181:endpoint>

</jsr181:endpoint>

</beans>

TheaboveconfigurationwillexposeHelloServicePojoasaserviceontheJBIbus,sothatfromnowonanyJBIcomponentcanexchangemessageswiththiscomponent.

Toeasilydemonstrateaccessingtheservice,wewillalsobindtheHTTPchanneltotheJBIbus.ThenasimpleHTMLclientcaninteractwiththebussendingthemessages.TheHTTPbindingisshowninthefollowingcode:

<beans

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:test="http://binildas.com/esb/jsrpojo">

<classpath>

<location>.</location>

</classpath>

<http:endpointservice="test:PojoBindService"

endpoint="PojoBindService"role="consumer"

targetService="test:helloService"

locationURI="http://localhost:8081/services/

PojoBindService"soap="true"

defaultMep="http://www.w3.org/2004/08/wsdl/

in-out">

<beans>

DeploymentConfigurationFordeployment,wewillpackagetherelevantartifactsfortheJSRPOJObindingintoaZIParchivenamedjsrbind-su.zip.Weneedtodeploythisarchiveontotheservicemix-jsr181componentandthatisdonethrough

thejbi.xmlasshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<jbixmlns="http://java.sun.com/xml/ns/jbi"

version="1.0">

<service-assembly>

<identification>

<name>JsrBindAssembly</name>

<description>JsrBindService

Assembly</description>

</identification>

<service-unit>

<identification>

<name>JsrBind</name>

<description>JsrBindServiceUnit</description>

</identification>

<target>

<artifacts-zip>jsrbind-su.zip</artifacts-zip>

<component-name>servicemix-jsr181</component-

name>

</target>

</service-unit>

</service-assembly>

</jbi>

Assaidearlier,wealsohaveaHTTPbindingtoeasilyaccessthePOJOservice.Hence,wehaveanotherjbi.xml,whichwillspecifyhowtodeploytheHTTPartifactsontotheservicemix-httpstandardJBIcomponent.Thisisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<jbixmlns="http://java.sun.com/xml/ns/jbi"

version="1.0">

<service-assembly>

<identification>

<name>HttpBindAssembly</name>

<name>HttpBindAssembly</name>

<description>HttpBindService

Assembly</description>

</identification>

<service-unit>

<identification>

<name>JsrProxy</name>

<description>HttpBindServiceUnit</description>

</identification>

<target>

<artifacts-zip>httpbind-su.zip</artifacts-zip>

<component-name>servicemix-http</component-name>

</target>

</service-unit>

</service-assembly>

</jbi>

DeployingandRunningtheSampleAsthefirststepandifyouhaven'tdoneitbefore,editexamples.PROPERTIESprovidedalongwiththecodedownloadforthischapterandchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Tobuildtheentirecodebaseanddeploythesample,changedirectorytoch09\Jsr181BindPojo,whichcontainsatop-levelbuild.xmlfile.Executeantasshowninthefollowingcommand:

cdch09\Jsr181BindPojo

ant

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder.

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

TheClient.htmlprovidedagaininthesamefoldercanbeusedtosendmessagestotestthedeployedservice.

AccessWSDLandGenerateAxis-basedStubstoAccessPOJORemotelyYoucannowaccesstheWSDLauto-generatedbyServiceMixoutoftheearlierPOJObinding.TheWSDLcanbeaccessedbypointingyourbrowsertothefollowingURL:

http://localhost:8081/services/PojoBindSer

vice/?wsdl

or

http://localhost:8081/services/PojoBindSer

vice/main.wsdl

EventhoughtheWSDLherehasnothingfancyaboutit,theimportantaspectisthatthisWSDLisauto-generatedbytheJBIbus,outoftheserviceInterface(theBI,discussedearlier)configuredinthejsr181:endpoint.LetusmakesurethattheWSDLisverysimilartoanyWSDLwegenerate

outfromanormalwebservice.LetuslisttheWSDLhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

xmlns:ns1="http://io.java"

xmlns:soap11="http://schemas.xmlsoap.org/soap/

envelope/"

xmlns:soap12="http://www.w3.org/2003/05/

soap-envelope"

xmlns:soapenc11="http://schemas.xmlsoap.org/soap/

encoding/"

xmlns:soapenc12="http://www.w3.org/2003/05/

soap-encoding"

xmlns:tns="http://binildas.com/esb/jsrpojo"

xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/

soap/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

targetNamespace="http://binildas.com/esb/jsrpojo">

<wsdl:types>

<xsd:schemaattributeFormDefault="qualified"

elementFormDefault="qualified"

targetNamespace="http://binildas.com/esb/jsrpojo"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:elementname="hello">

<xsd:complexType>

<xsd:sequence>

<xsd:elementmaxOccurs="1"minOccurs="1"

name="in0"nillable="true"type="xsd:string">

<xsd:sequence>

</xsd:complexType>

</xsd:element>

<xsd:elementname="helloResponse">

<xsd:complexType>

<xsd:sequence>

<xsd:elementmaxOccurs="1"minOccurs="1"

name="out"nillable="true"type="xsd:string">

<xsd:sequence>

</xsd:complexType>

</xsd:element>

<xsd:elementname="IOException"

type="ns1:IOException">

<xsd:schema>

<xsd:schemaattributeFormDefault="qualified"

elementFormDefault="qualified"

targetNamespace="http://io.java"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<xsd:complexTypename="IOException">

<xsd:schema>

</wsdl:types>

<wsdl:messagename="helloRequest">

<wsdl:partelement="tns:hello"name="parameters">

</wsdl:part>

</wsdl:message>

<wsdl:messagename="helloResponse">

<wsdl:partelement="tns:helloResponse"

name="parameters">

</wsdl:part>

</wsdl:message>

<wsdl:messagename="IOException">

<wsdl:partelement="tns:IOException"

name="IOException">

</wsdl:part>

</wsdl:message>

<wsdl:portTypename="helloServicePortType">

<wsdl:operationname="hello">

<wsdl:inputmessage="tns:helloRequest"

name="helloRequest">

</wsdl:input>

<wsdl:outputmessage="tns:helloResponse"

name="helloResponse">

</wsdl:output>

<wsdl:faultmessage="tns:IOException"

name="IOException">

</wsdl:fault>

</wsdl:operation>

</wsdl:portType>

<wsdl:bindingname="PojoBindServiceBinding"

type="tns:helloServicePortType">

<wsdlsoap:bindingstyle="document"

transport="http://schemas.xmlsoap.org/

soap/http">

<wsdl:operationname="hello">

<wsdlsoap:operationsoapAction="">

<wsdl:inputname="helloRequest">

<wsdlsoap:bodyuse="literal">

<wsdl:input>

<wsdl:outputname="helloResponse">

<wsdlsoap:bodyuse="literal">

<wsdl:output>

<wsdl:faultname="IOException">

<wsdlsoap:faultname="IOException"use="literal">

<wsdl:fault>

</wsdl:operation>

</wsdl:binding>

<wsdl:servicename="PojoBindService">

<wsdl:portbinding="tns:PojoBindServiceBinding"

name="PojoBindService">

<wsdlsoap:address

location="http://localhost:8081/

services/PojoBindService/">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

WewillnowusetheApacheAxistoolstoauto-generatetheclient-sidestubsandthebindingclassesusingwhichwecanwriteasimpleJavaclientclasstoaccesstheservicethroughaHTTPchannel.TheAxisclientclassesareplacedinthedirectorych09\Jsr181BindPojo\03_AxisClient.

Todothat,wehavetousethewsdl2javaanttask.Letusdeclarethetaskdefinitionandexecutethattasktogeneratethestubclasses.

<taskdefname="wsdl2java""

classname="org.apache.axis.tools.ant.wsdl.Wsdl2javaAntTask"

loaderref="axis">

<classpathrefid="classpath">

<taskdef>

<targetname="wsdl2java">

<javaclassname="org.apache.axis.wsdl.WSDL2Java"

fork="true"failonerror="true">

<argvalue="-o">

<argvalue="${src}">

<argvalue="-x">

<argvalue="http:/io.java">

<arg

value="http:/localhost:8081/services/PojoBindService/

main.wsdl">

<classpath>

<pathrefid="classpath">

<pathelementlocation="${build}">

<classpath>

</java>

</target>

ThetaskwillextractWSDLfromthespecifiedlocationandgeneratethefollowingclient-sideartifacts:

com\binildas\esb\jsrpojo\HelloServicePortType.java

com\binildas\esb\jsrpojo\PojoBindService.java

com\binildas\esb\jsrpojo\PojoBindServiceBindingStub.java

com\binildas\esb\jsrpojo\PojoBindServiceLocator.java

TheClientJavaclasscanbewrittenagainstthesegeneratedfilesasfollows:

publicclassClient

{

privatestaticStringwsdlUrl=

"http://localhost:8081/services/

PojoBindService/main.wsdl";

privatestaticStringnamespaceURI=

"http://binildas.com/esb/jsrpojo";

privatestaticStringlocalPart=

"PojoBindService";

protectedvoidexecuteClient(String[]args)throws

Exception

{

PojoBindServicepojoBindService=null;

HelloServicePortTypehelloServicePortType=null;

if(args.length==3)

{

pojoBindService=new

PojoBindServiceLocator(args[0],new

QName(args[1],args[2]));

}

else

{

pojoBindService=new

PojoBindServiceLocator(wsdlUrl,new

QName(namespaceURI,localPart));

}

helloServicePortType=

pojoBindService.getPojoBindService();

log("ResponseFromServer:"+

helloServicePortType.hello("Binil"));

}

publicstaticvoidmain(String[]args)throws

Exception

{

Clientclient=newClient();

client.executeClient(args);

}

}

TobuildtheentireAxisclientcodebase,assumingthatServiceMixisupandrunning,changedirectorytoch09\Jsr181PojoAccessBus\04_AxisClient,whichcontainsatop-levelbuild.xmlfile.Executeantasfollows:

cdch09\Jsr181PojoAccessBus

ant

ThiswillgeneratetherequiredAxisclient-sidestubsandcompiletheclientclasses.Nowtoruntheclient,executethefollowingcommand:

antrun

AccessingJBIBusSampleIntheprevioussample,wehaveseenhowtobindaPOJOtoJBIandaccesstheserviceagainusingthestandardwebserviceaccessmechanisms.Occasionally,yourcomponentsmayalsowanttoaccesstheJBIbusdirectlyatprogrammingAPI-level,andwecandothatusingthenumerousAPIsprovidedbyServiceMixandJBI.

ThepreferredmechanismtoaccessJBIfromyourcomponentistofirstgettheComponentContextimplementationandfromtheretraversetheotherJBIAPIs.

<jsr181:endpointannotations="none"

service="some:Service"

serviceInterface="some.Interface">

<jsr181:pojo>

<beanclass="some.Pojo">

<propertyname="context"ref="context">

<bean>

</jsr181:pojo>

</jsr181:endpoint>

Correspondingly,wewillnowhaveourPojo(Oh,yes;ourPOJOsaregettingbulkierhere!)classintowhichtheJBIcontainercaninjectareferenceoftheComponentContext.Thepojoclassisreproducedinthefollowingcode:

publicclassPojo

{

privatejavax.jbi.component.ComponentContext

context;

publicvoid

setContext(javax.jbi.component.ComponentContext

context)

{

this.context=context;

}

}

ComponentContextistheJBIAPIusingwhichwecanaccesstheunderlyingDeliveryChannel.Thisisshowninthefollowingcode:

publicinterfaceComponentContext

{

publicDeliveryChannelgetDeliveryChannel()throws

MessagingException;

MessagingException;

}

DeliveryChannelcanbeusedtosendmessagestotheJBIbus.ItistobenotedthatonlysendSync()isallowedforactiveJBIexchanges(butyouhavetousesend()forDONEorERRORstatusexchanges).Thisisshowninthefollowingcode:

publicinterfaceDeliveryChannel

{

publicMessageExchangeaccept()throws

MessagingException;

publicvoidsend(MessageExchangeexchange)throws

MessagingException;

publicbooleansendSync(MessageExchangeexchange)

throwsMessagingException;

publicbooleansendSync(MessageExchangeexchange,

longtimeout)throwsMessagingException;

}

SampleUseCaseforAccessingJBIBusWewillhaveanotherfullsampleforPOJObindingtodemonstratehowtoaccesstheJBIbusfromwithinaPOJO.Asdescribedabove,wecanuseComponentContexttoaccesstheDeliveryChanneltosendmessagestotheJBIbus.AnotherwaytointeractwiththeJBIbusistousetheclientAPI.LetusdefineasampleusecasetoaccesstheJBIbus.

Wewillhavethefollowingcomponentstoimplementthesampleusecase:

Client

HTTPbinding

JSRPOJOBridge

JSRPOJODestination

Thesecomponentsareintegratedasshowninthefollowingfigure.Whentheclientsendsamessage,themessageflowthroughtheNMRthroughvariousJBIcomponentsismarkedbynumbersinsequence.

Theabovecomponentswillexchangemessagesinthefollowingsequence:

1. ClientsendsmessagetoHTTPbinding.

2. HTTPbindingroutesmessagestodestinationthroughJBIbus.

3. JSRPOJOBridgebeingthedestinationfortheabovemessage,willacceptthemessage.

4. TheJSRPOJOBridgewillperformthefollowingstepstosendthenextmessagetotheJBIbus.

1. ItfirstcreatesareferenceofServiceMixClient.

ServiceMixClientclient=new

ServiceMixClientFacade(this.context);

2. ItthencreatesaQNametoreferthedestinationservice.

QNameservice=new

QName("http://binildas.com/esb/

jsrpojo","destinationHelloService");

3. UsingtheaboveServiceMixClientandtheservicereference,itthencreatesanEndpointResolver.

EndpointResolverresolver=

client.createResolverForService(service);

4. Now,wecansendthemessagetotheJBIbususingtheServiceMixClient.

client.send(resolver,null,null,

messageToDespatch);

5. Now,destinationHelloServiceistheservicepointingtoJSRPOJODestination.So,themessagefromtheJBIbuswillbeacceptedbyJSRPOJODestination.

Thefollowingfigureshowstheabovesequencesofevents:

SampleCodeListingThereisnotmuchdifferenceinthecodethanwhatwehaveseenintheprevioussample,buttheBridgeHelloServicePojoclasswillbelistedasfollows,todiscussafewpoints:

publicclassBridgeHelloServicePojoimplements

BridgeHelloServiceBI

{

privateComponentContextcontext;

publicvoidsetContext(ComponentContextcontext)

{

this.context=context;

}

publicStringbroker(Stringphrase)

{

try

{

send(phrase);

}

catch(JBIExceptionjbiException)

catch(JBIExceptionjbiException)

{

jbiException.printStackTrace();

returnjbiException.getMessage();

}

return"Success";

}

privatevoidsend(Stringmessage)throws

javax.jbi.JBIException

{

System.out.println("BridgeHelloServicePojo.1.

message:"+message);

ServiceMixClientclient=new

ServiceMixClientFacade(this.context);

QNameservice=newQName(namespaceURI,

localPart);

EndpointResolverresolver=

client.createResolverForService(service);

StringmessageToDespatch=getMessage(message);

client.send(resolver,null,null,

messageToDespatch);

}

privateStringgetMessage(Stringmessage)

{

StringBufferstringBuffer=newStringBuffer();

stringBuffer.append("<hello>").append("

<helloRequest>").append("<message

xmlns=\"http://soap\">"+message+"</message>")

.append("</helloRequest>").append("</hello>");

returnstringBuffer.toString();

}

}

Perhaps,youmightgetstuckatthemessagebuildingsectionofthecodeabove.ThiswillleadtothefollowingXMLcode:

<hello>

<helloRequest>

<messagexmlns=\"http://soap\">"+message+"

</message>

</message>

</helloRequest>

</hello>

ThisisslightlydifferentfromtheusualSOAPenvelopedmessages,whichwesenttotheJBIbus.Thedifferenceisthatwedon'thaveaSOAPenvelope,butjustthemessage.ThisisbecausesimplebindingthePOJOusingservicemix-jsr181requirestheconsumertosendjustanormalized(XML)message,andnotaSOAPmessage.

Build,Deploy,andRuntheSampleThecodebaseforthissampleislocatedatch09\Jsr181PojoAccessBus.Tobuildtheentirecodebaseanddeploythesample,changedirectorytoch09\Jsr181PojoAccessBus,whichcontainsatop-levelbuild.xmlfile.Executeantasfollows:

cdch09\Jsr181PojoAccessBus

ant

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder,asshowninthefollowingcommands:

cdch09\Jsr181PojoAccessBus

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

TheClient.htmlfileprovidedagaininthesamefolder

canbeusedtosendmessagestotestthedeployedservice.

Forcompletenessofthesample,wealsohavecodetoaccesstheserviceusingtheAxisclientinthefolderch09\Jsr181PojoAccessBus\04_AxisClient.

TobuildtheentireAxisclientcodebase,assumingthatServiceMixisupandrunning,changedirectorytoch09\Jsr181PojoAccessBus\04_AxisClient,whichcontainsatop-levelbuild.xmlfile.Executeantasfollows:

cdch09\Jsr181PojoAccessBus

ant

ThiswillgeneratetherequiredAxisclient-sidestubsandcompiletheclientclasses.Nowtoruntheclient,executethefollowingcommand:

antrun

SummaryThischapterdiscussedPOJOclasses,andhowwecanhookthemontotheJBIbus.Hence,theservicesprovidedbytheseclassescanevenbeaccessedremotely,justlikeyouaccessanormalwebservice.JBIisallaboutSOIandthusprovidesaframeworkforintegratingcomponentsasservicestothebus.

Thisiswhatwehaveseeninthischapter,whenweboundaPOJOtotheNMRandaccesseditthroughnormalwebservicechannels.

Inthenextchapter,wewilllookintoyetanothercommonscenariofoundinproductionanddeploymentofwebservicesnamelyWebServicesGateways.

Chapter10.BindWebServicesinESB—WebServicesGatewaySinceSOIisallaboutintegratingmultipleSOA-basedsystems,webservicesplayacriticalroleintheintegrationspace.Thischapterisallabouttheimportanceofwebservicesinintegration.WewillusethesamplestoillustratehowtobindwebserviceswiththeServiceMixESBtofacilitateintegration.

Wewillcoverthefollowinginthischapter:

Webservicesandbinding

IntroductiontoHTTP

ServiceMix'sservicemix-httpcomponent

TheconsumerandproviderrolesfortheServiceMixJBIcomponents

servicemix-httpintheconsumerandproviderroles

Webservicebinding(Gateway)sample

WebServicesWebservicesseparateouttheservicecontractfromtheserviceinterface.ThisfeatureisoneofthemanycharacteristicrequiredforanSOA-basedarchitecture.Thus,eventhoughit

isnotmandatorythatweusethewebservicetoimplementanSOA-basedarchitecture,yetitisclearlyagreatenablerforSOA.

Webservicesarehardware,platform,andtechnologyneutralTheproducersand/orconsumerscanbeswappedwithoutnotifyingtheotherparty,yettheinformationcanflowseamlessly.AnESBcanplayavitalroletoprovidethisseparation.

BindingWebServicesAwebservice'scontractisspecifiedbyitsWSDLanditgivestheendpointdetailstoaccesstheservice.WhenwebindthewebserviceagaintoanESB,theresultwillbeadifferentendpoint,whichwecanadvertisetotheconsumer.Whenwedoso,itisverycriticalthatwedon'tloseanyinformationfromtheoriginalwebservicecontract.

WhyAnotherIndirection?Therecanbemultiplereasonsforwhywerequireanotherlevelofindirectionbetweentheconsumerandtheproviderofawebservice,bybindingatanESB.

Systemsexisttodaytosupportbusinessoperationsasdefinedbythebusinessprocesses.Ifasystemdoesn'tsupportabusinessprocessofanenterprise,thatsystemisoflittleuse.Businessprocessesareneverstatic.Iftheyremainstaticthenthereisnogrowthorinnovation,anditisdoomedtofail.

Hence,systemsorservicesshouldfacilitateagilebusinessprocesses.Thegoodarchitectureanddesignpracticeswillhelptobuild"servicestolast"butthatdoesn'tmeanourbusinessprocessesshouldbestable.Instead,businessprocesseswillevolvebyleveragingtheexistingservices.Thus,weneedaprocessworkbenchtoassembleandorchestrateserviceswithwhichwecan"MixandMatch"theservices.ESBisoneofthearchitecturaltopologieswherewecandothemixandmatchofservices.Todothis,wefirstbindtheexisting(andlonglasting)servicestotheESB.ThenleveragetheESBservices,suchasaggregationandtranslation,tomixandmatchthemandadvertisenewprocessesforbusinessestouse.

Moreover,therearecrossserviceconcernssuchasversioning,management,andmonitoring,whichweneedtotakecaretoimplementtheSOAathigherlevelsofmaturity.TheESBisagainonewaytodotheseaspectsofserviceorientation.

HTTPHTTPistheWorldWideWeb(www)protocolforinformationexchange.HTTPisbasedoncharacter-orientedstreamsandisfirewall-friendly.Hence,wecanalsoexchangeXMLstreams(whichareXMLencodedcharacterstreams)overHTTP.InawebserviceweexchangeXMLintheSOAP(SimpleObjectAccessProtocol)formatoverHTTP.Hence,theHTTPheadersexchangedwillbeslightlydifferentthananormalwebpageinteraction.Asamplewebservicerequestheaderisshownasfollows:

GETAxisEndToEndservices/HelloWebService?WSDL

HTTP/1.1

User-Agent:Java/1.6.0-rc

Host:localhost:8080

Accept:text/html,image/gif,image/jpeg,;q=.2,

/*;q=.2

Connection:keep-alive

POSTAxisEndToEndservices/HelloWebService

HTTP/1.0

Content-Type:text/xml;charset=utf-8

Accept:application/soap+xml,application/dime,

multipart/related,text/*

User-Agent:Axis/1.4

Host:localhost:8080

Cache-Control:no-cache

Pragma:no-cache

SOAPAction:""

Content-Length:507

Thefirstlinecontainsamethod,aURIandanHTTPversion,eachseparatedbyoneormoreblankspaces.Thesucceedinglinescontainmoreinformationregardingthewebserviceexchanged.

ESB-basedintegrationheavilyleveragestheHTTPprotocolduetoitsopennature,maturity,andacceptability.WewillnowlookatthesupportprovidedbytheServiceMixinusingHTTP.

ServiceMix'sservicemix-httpBindingexternalwebservicesattheESBlayercanbedoneinmultiplewaysbutthebestwayistoleverageJBIcomponents

suchastheservicemix-httpcomponentwithinServiceMix.WewilllookindetailathowtobindthewebservicesontotheJBIbus.

servicemix-httpinDetailservicemix-httpisusedforHTTPorSOAPbindingofservicesandcomponentsintotheServiceMixNMR.ForthisServiceMixusesanembeddedHTTPserverbasedontheJetty.

InChapter3,youhavealreadyseenthefollowingtwoServiceMixcomponents:

org.apache.servicemix.components.http.HttpInvoker

org.apache.servicemix.components.http.HttpConnector

Asoftoday,thesecomponentsaredeprecatedandthefunctionalityisreplacedbytheservicemix-httpstandardJBIcomponent.Afewofthefeaturesoftheservicemix-httpareasfollows:

SupportsSOAP1.1and1.2

SupportsMIMEwithattachments

SupportsSSL

SupportsWS-AddressingandWS-Security

SupportsWSDL-basedandXBean-baseddeployments

SupportforallMEPsasconsumersorproviders

Sinceservicemix-httpcanfunctionbothasaconsumer

andaprovider,itcaneffectivelyreplacethepreviousHttpInvokerandHttpConnectorcomponent.

ConsumerandProviderRolesWhenwespeakoftheConsumerandProviderrolesfortheServiceMixcomponents,thedifferenceisverysubtleatfirstsight,butveryimportantfromaprogrammerperspective.ThefollowingfigureshowstheConsumerandProviderrolesintheServiceMixESB:

Theabovefigureshowstwoinstancesofservicemix-httpdeployedintheServiceMixESB,oneinaproviderrole

andtheotherintheconsumerrole.Asitisevident,theserolesarewithrespecttotheNMRoftheESB.Inotherwords,aconsumerroleimpliesthatthecomponentisaconsumertotheNMRwhereasaproviderroleimpliestheNMRistheconsumertothecomponent.Basedontheseroles,theNMRwilltakeresponsibilityofanyformatorprotocolconversionsfortheinteractingcomponents.

Letusalsointroducetwomorepartiesheretomaketheroleofaconsumerandaproviderclear—aclientandaservice.Inatraditionalprogrammingparadigm,theclientinteractsdirectlywiththeserver(orservice)toavailthefunctionality.IntheESBmodel,boththeclientandtheserviceinteractwitheachotheronlythroughtheESB.Hence,theclientandtheserviceneedpeerswiththeirrespectiverolesassigned,whichinturnwillinteractwitheachother.Thus,theESBconsumerandproviderrolescanberegardedasthepeerrolesfortheclientandtheservicerespectively.

AnyclientrequestwillbedelegatedtotheconsumerpeerwhointurninteractswiththeNMR.ThisisbecausetheclientisunawareoftheESBandtheNMRprotocolorformat.However,theservicemix-httpconsumerknowshowtointeractwiththeNMR.Henceanyrequestfromtheclientwillbetranslatedbytheservicemix-httpconsumeranddeliveredtotheNMR.Ontheservicesidealso,theNMRneedstoinvoketheservice.Buttheserverserviceisneutralofanyspecificvendor'sNMRanddoesn'tunderstandtheNMRlanguageassuch.Apeerproviderrolewillhelphere.TheproviderreceivestherequestfromtheNMR,translatesitintotheactualformatorprotocoloftheserverserviceandinvokes

theservice.Anyresponsewillalsofollowthereversesequence.

servicemix-httpXBeanConfigurationTheservicemix-httpcomponentssupportstheXBean-baseddeployment.Sincetheservicemix-httpcomponentcanbeconfiguredinboththeconsumerandproviderroles,wehavetwosetsofconfigurationparametersforthecomponent.Letuslookintothemainconfigurationparameters:

servicemix-httpasconsumer:Asampleservicemix-httpconsumercomponentconfigurationisshownasfollows:

<http:endpoint

service="test:MyConsumerService"

endpoint="HelloWebService"role="consumer"

targetService="test:IHelloWebService"

locationURI="http://localhost:8081/services/

HelloWebService"soap="true"

defaultMep="http://www.w3.org/2004/08/wsdl/in-out"

wsdlResource="http://localhost:8080AxisEndToEnd

services/HelloWebService?WSDL"/>

Thefollowingtablegivestheexplanationforthemainconfigurationparameters:

AttributeNa

Type Description

MandatoryorNot

me

service

QName

Servicenameoftheproxyendpoint Mandatory

endpoint

String

Endpointnameoftheproxyendpoint

Mandatory

interfaceName

QName

Interfacenameoftheproxyendpoint

NotMandatory

targetService

QName

Servicenameofthetargetendpoint NotMandatory.Defaultisthevalueoftheserviceattribute

targetEndpoint

String

Endpointnameofthetargetendpoint

NotMandatory.Defaultisthevalueoftheendpointattribute

role Stri Whetheraconsumeroraprovider Mandatory.Value

role String

Whetheraconsumeroraprovider Mandatory.Valueshouldbeconsumer

locationURI

URI

HttpURLwherethisproxyendpointwillbeexposedsothattheESBclientscanaccesstheproxyservice.

Mandatory

defaultMEP

URI

TheMEPURIbywhichclientsinteractwiththeconsumercomponent

NotMandatory

soap

boolean

Ifitistrue,thecomponentwillparsetheSOAPenvelopeandpassthecontentstotheNMR

NotMandatory.Defaultvalueisfalse.

wsdlResource

SpringResource

Ifitisset,theWSDLwillberetrievedfromthisconfiguredSpringresource.

NotMandatory

Thus,thelocationURIattributeintheservicemix-httpconsumerreferstotheHttpURLwherethisproxyendpointisexposed,sothattheESBclientscanaccesstheproxyservice.LaterwewilllookathowtogeneratestaticclientstubsoutofthisproxyURI.

servicemix-httpasprovider:Whileconfiguringtheprovider,thereareafewaspectstobetakencareofwithrespecttotheWSDL.IfwehavethesampleWSDLasshownasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

targetNamespace="http://AxisEndToEnd.axis.

apache.binildas.com"

xmlns:impl="http://AxisEndToEnd.axis.apache.

binildas.com"><!--otherdescriptions-->

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebServiceSoapBinding"

name="HelloWebService">

<wsdlsoap:address

location="http://localhost:8080/

AxisEndToEnd/services/HelloWebService">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

Now,whileconfiguringtheprovidercomponentyouneedtoensurethattheservice(IHelloWebService)andtheendpoint(HelloWebService)matchtheservicenameandportelementsoftheWSDLthatyouusetocorrectlyreturntheWSDLfortheendpoint.Moreover,theservicenamewillusethetargetNamespacefortheWSDL(http://AxisEndToEnd.axis.apache.binildas.com).

Asampleservicemix-httpprovidercomponentconfigurationisshownasfollows:

<http:endpointservice="test:IHelloWebService"

endpoint="HelloWebService"role="provider"

Thefollowingtablethegivestheexplanationforthemainconfigurationparameters:

AttributeName

Type Description MandatoryorNot

service

QName

Servicenameoftheexposedendpoint Mandatory

endpoint

String Endpointnameoftheexposedendpoint Mandatory

interfaceName

QName

Interfacenameoftheexposedendpoint NotMandatory

locationURI="http://localhost:8080AxisEndToEnd

services/HelloWebService"

soap="true"

soapAction=""

wsdlResource="http://localhost:8080AxisEndToEnd

services/HelloWebService?WSDL"/>

role String Whetheraconsumeroraprovider Mandatory.Valueshouldbeprovider

locationURI

URI HttpURLofthetargetservice. Mandatory

soap boolean

Ifitistrue,thecomponentwillparsetheSOAPenvelopeandpassthecontentstotheNMR

NotMandatory.Defaultvalueisfalse.

soapAction

String TheSOAPActionheadertobesendoverHTTPwheninvokingthewebservice

NotMandatory.Defaultvalueis"".

wsdlResource

SpringResource

Ifitisset,theWSDLwillberetrievedfromthisconfiguredSpringresource.

NotMandatory

servicemix-httpLightweightConfigurationInadditiontotheXBean-basedconfiguration,servicemix-httpcanalsobedeployedbasedonthelightweightmodetouseinanembeddedServiceMix.Theconfigurationwouldbeasfollows:

<sm:activationSpec>

<sm:component>

<http:component>

<http:endpoints>

<http:endpointservice="test:IHelloWebService"

endpoint="HelloWebService"role="provider"

locationURI="http://localhost:8080/

AxisEndToEnd/services/HelloWebService"soap="true"soapAction=""

wsdlResource="http://localhost:8080/AxisEndToEnd/services/

HelloWebService?WSDL">

<http:endpointservice="test:MyConsumerService"

endpoint="HelloWebService"role="consumer"

targetService="test:IHelloWebService"

locationURI="http:/localhost:8081/services/HelloWebService"

soap="true"

defaultMep="http://www.w3.org/2004/08/wsdl/in-out"

wsdlResource="http://localhost:8080/AxisEndToEnd/services/

HelloWebService?WSDL">

<http:endpoints>

</http:component>

</sm:component>

</sm:activationSpec>

WebServiceBindingSampleWewillnowlookatacompletesampleofhowtobindawebservicetotheServiceMix.Whiledoingso,wewillalsoseehowtousetheApacheAxisclient-sidetoolstogeneratestubsbasedonthebindingatServiceMix.NormallywepointtotheactualWSDLURLtogenerateclientstubs,butinthisexamplewewillpointthetoolstotheServiceMixbinding.ThentheServiceMixbindingwillactcompletelyasthewebservicegatewayvisibletotheexternalclients,thusshieldingtheactualwebserviceinthebackground.

SampleUseCaseByusingawebservicesgateway,youcanusetheintermediationtobuildanddeploythewebservicesroutingapplication.Butkeepinmindthattheroutingisjustoneofthevarioustechnicalfunctionalitiesthatyoucanimplementatthegateway.Foroursampleusecase,wehaveanexternalwebservice,deployedandhostedinanoderemotetotheESB.IntheESB,wewillsetupaWebServicesGateway,whichcanproxytheremotewebservice.Theentiresetupisshowninthefollowingfigure:

Alongwiththepreviousdiscussion,weneedtheservicemix-httpintheconsumerandproviderroles.MyConsumerServiceisaservicemix-httpcomponentintheconsumerroleandIHelloWebServiceisaservicemix-httpcomponentintheproviderrole.Bothofthemareshowninthefollowing

figure:

LetusnowtakeacloserlookatthegatewayconfiguredintheESB.Here,weconfigureservicemix-httpinboththeconsumerandproviderrolesandhookittotheNMR.AnyclientrequestsareinterceptedbytheconsumerandtheconsumerthensendstherequestonbehalfoftheclienttotheNMR.Fromtheretherequestwillberoutedtothedestinationwebservicethroughtheprovider.Themessageflowismarkedinsequenceinthefollowingfigure:

DeploytheWebServiceAsafirststep,ifyouhaven'tdoneitbefore,editexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter),andchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Wehaveasimplewebserviceinthecodebasepresentinthefolderch10\ServiceMixHttpBinding\01_ws.Todeploythewebservice,firstchangedirectorytothech10\ServiceMixHttpBindingfolderandexecutetheantcommandasfollows:

cdch10\ServiceMixHttpBinding

ant

Infact,thebuild.xmlfilewillcallthebuildinthesubprojectstobuildthewebserviceaswellastheServiceMixsubproject.

Thewebserviceisbuiltcompletelyandthewarfilecanbefoundinthefolderch10\ServiceMixHttpBinding\01_ws\dist\AxisEndToEnd.war

.Todeploythewebservice,dropthiswarfileintoyourfavoritewebserver'swebappsfolderandrestartthewebserver,ifnecessary.

Nowtomakesurethatyourwebservicedeploymentworksfine,wehaveprovidedawebservicetestclient.Toinvokethetestclient,executethefollowingcommands:

cdch10\ServiceMixHttpBinding\01_ws

antrun

WecanalsocheckthewebservicedeploymentbyaccessingtheWSDLfromtheURL:http://localhost:8080AxisEndToEndservices/HelloWebServ

ice?WSDL

LetuslistouttheWSDLhere,sincewewanttocompareitwiththeWSDLaccessedfromtheServiceMixbindinglatertocrosscheckthesimilarities.Thisisprovidedinch10\ServiceMixHttpBinding\HelloWebService-axis.wsdl

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitionstargetNamespace="http://AxisEndToEnd.axis.

apache.binildas.com"

xmlns:apachesoap="http://xml.apache.org/xmlsoap"

xmlns:impl="http://AxisEndToEnd.axis.apache.binildas.com"

xmlns:intf="http://AxisEndToEnd.axis.apache.binildas.com"

xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<wsdl:types>

<schemaelementFormDefault="qualified"

targetNamespace="http://AxisEndToEnd.axis.apache.binildas.com"

xmlns="http://www.w3.org/2001/XMLSchema">

<elementname="hello">

<complexType>

<sequence>

<elementname="in0"type="xsd:string">

<sequence>

</complexType>

</element>

<elementname="helloResponse">

<complexType>

<sequence>

<elementname="helloReturn"type="xsd:string">

<sequence>

</complexType>

</element>

</schema>

</wsdl:types>

<wsdl:messagename="helloRequest">

<wsdl:partelement="impl:hello"name="parameters">

<wsdl:message>

<wsdl:messagename="helloResponse">

<wsdl:partelement="impl:helloResponse"name="parameters">

<wsdl:message>

<wsdl:portTypename="IHelloWeb">

<wsdl:operationname="hello">

<wsdl:inputmessage="impl:helloRequest"name="helloRequest"/>

<wsdl:outputmessage="impl:helloResponse"name="helloResponse">

<wsdl:operation>

</wsdl:portType>

<wsdl:bindingname="HelloWebServiceSoapBinding"

type="impl:IHelloWeb">

<wsdlsoap:bindingstyle="document"transport="http://schemas.

xmlsoap.org/soap/http">

<wsdl:operationname="hello">

<wsdlsoap:operationsoapAction="">

<wsdl:inputname="helloRequest">

<wsdlsoap:bodyuse="literal">

<wsdl:input>

<wsdl:outputname="helloResponse">

<wsdlsoap:bodyuse="literal">

<wsdl:output>

</wsdl:operation>

</wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:portbinding="impl:HelloWebServiceSoapBinding"

name="HelloWebService">

<wsdlsoap:addresslocation="http://localhost:8080/

AxisEndToEnd/services/HelloWebService">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

XBean-basedservicemix-httpBinding

ForXBean-baseddeploymentofservicemix-http,ourxbean.xmlmatchesthefollowing:

<beansxmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:test="http://AxisEndToEnd.axis.apache.binildas.com">

<classpath>

<location>.</location>

</classpath>

<http:endpointservice="test:IHelloWebService"

endpoint="HelloWebService"role="provider"

locationURI="http://localhost:8080AxisEndToEnd

services/HelloWebService"soap="true"soapAction=""

wsdlResource="http://localhost:8080AxisEndToEnd

services/HelloWebService?WSDL">

<http:endpointservice="test:MyConsumerService"

endpoint="HelloWebService"role="consumer"

targetService="test:IHelloWebService"

locationURI="http:/localhost:8081/services/HelloWebService"

soap="true"defaultMep="http://www.w3.org/2004/08/wsdl/in-out"

wsdlResource="http://localhost:8080AxisEndToEnd

services/HelloWebService?WSDL">

<beans>

Thepreviousexecutionofanthasalreadybuiltandpackagedtheserviceassemblyforthesample.

DeployingandRunningtheSampleTodeploytheServiceMixsample,wehavethefollowingservicemix.xml:

<?xmlversion="1.0"encoding="UTF-8"?>

<beansxmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:binil="http://www.binildas.com/voipservice">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"value="classpath:servicemix.properties"

>

<bean>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<sm:containerid="jbi"MBeanServer="#jmxServer"

useMBeanServer="true"createMBeanServer="true"rootDir="./wdir"

installationDirPath="./install"deploymentDirPath="./deploy"

flowName="seda">

<sm:activationSpecs>

</sm:activationSpecs>

</sm:container>

</beans>

TobringuptheServiceMix,changedirectorytoch10\ServiceMixHttpBindingandexecutetheServiceMixscriptasfollows.

cdch10\ServiceMixHttpBinding

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

WecannowtestourServiceMixdeploymentbyusingthefollowingtestclient:

ch10\ServiceMixHttpBinding\Client.html

AccessWSDLandGenerateAxisStubstoAccesstheWebServiceRemotely

Nowforthereallycoolstuff.Aswediscussedearlier,wehavesetuptheServiceMixasaseparatewebservicegatewayinfrontoftheactualwebservicedeployment.NowwehavetocheckwhetherwecanaccesstheWSDLfromtheServiceMix.Forthis,wecanpointourbrowserusingthestandardWSDLquerystring,like:

http://localhost:8081/services/HelloWebService/?wsdl

or

http://localhost:8081/services/HelloWebService/main.ws

dl

Notethat,theaboveURLpointstothelocationURIattributeconfiguredfortheconsumercomponent,whichishttp://localhost:8081/services/HelloWebService.TheWSDLplacedinlocationch10\ServiceMixHttpBinding\HelloWebService-esb.wsdl,matchesthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

xmlns:apachesoap="http://xml.apache.org/xmlsoap"

xmlns:impl="http://AxisEndToEnd.axis.apache.binildas.com"

xmlns:intf="http://AxisEndToEnd.axis.apache.binildas.com"

xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

targetNamespace="http://AxisEndToEnd.axis.apache.binildas.com">

<wsdl:types>

<schemaxmlns="http://www.w3.org/2001/XMLSchema"

elementFormDefault="qualified"

targetNamespace="http://AxisEndToEnd.axis.apache.binildas.com">

<elementname="hello">

<complexType>

<sequence>

<elementname="in0"type="xsd:string">

<sequence>

</complexType>

</element>

<elementname="helloResponse">

<complexType>

<sequence>

<elementname="helloReturn"type="xsd:string">

<sequence>

</complexType>

</element>

</schema>

</wsdl:types>

<wsdl:messagename="helloRequest">

<wsdl:partelement="impl:hello"name="parameters">

</wsdl:part>

</wsdl:message>

<wsdl:messagename="helloResponse">

<wsdl:partelement="impl:helloResponse"name="parameters">

</wsdl:part>

</wsdl:message>

<wsdl:portTypename="IHelloWeb">

<wsdl:operationname="hello">

<wsdl:inputmessage="impl:helloRequest"name="helloRequest">

</wsdl:input>

<wsdl:outputmessage="impl:helloResponse"name="helloResponse">

</wsdl:output>

</wsdl:operation>

</wsdl:portType>

<wsdl:bindingname="HelloWebServiceBinding"

type="impl:IHelloWeb">

<wsdlsoap:bindingstyle="document"

transport="http://schemas.xmlsoap.org/soap/http">

<wsdl:operationname="hello">

<wsdlsoap:operationsoapAction="">

<wsdl:inputname="helloRequest">

<wsdlsoap:bodyuse="literal">

<wsdl:input>

<wsdl:outputname="helloResponse">

<wsdlsoap:bodyuse="literal">

<wsdl:output>

</wsdl:operation>

</wsdl:binding>

<wsdl:servicename="MyConsumerService">

<wsdl:portbinding="impl:HelloWebServiceBinding"

name="HelloWebService">

<wsdlsoap:addresslocation="http://localhost:8081/

services/HelloWebService/">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

IfwecomparethetwoWSDL,themajordifferenceisintheservicedescriptionsection.Here,ServiceMixformstheserviceandportnametakingvaluesfromserviceandendpointattributesoftheconsumerservice—MyConsumerServiceandHelloWebServicerespectively.

IfweareabletoretrievetheWSDL,thenextstepistousetheApacheAxistoolstoauto-generatetheclient-sidestubsandbindingclasses,usingwhichwecanwritesimpleJavaclientcodetoaccesstheservicethroughHTTPchannel.TheAxisclientclassesareplacedinthedirectorych10\ServiceMixHttpBinding\03_AxisClient.

Todothat,wehavetousethewsdl2javaanttask.Letusfirstdeclarethetaskdefinitionandexecutethattasktogeneratethestubclasses.

<taskdefname="wsdl2java"

classname="org.apache.axis.tools.ant.wsdl.Wsdl2javaAntTask"

loaderref="axis">

<classpathrefid="classpath">

<taskdef>

<targetname="wsdl2java">

<javaclassname="org.apache.axis.wsdl.WSDL2Java"fork="true"

failonerror="true">

<argvalue="-o">

<argvalue="${src}">

<argvalue="-x">

<argvalue="http:/io.java">

<argvalue="http:/localhost:8081/services/HelloWebService/

main.wsdl">

<classpath>

<pathrefid="classpath">

<pathelementlocation="${build}">

<classpath>

</java>

</target>

ThetaskwillextracttheWSDLfromthespecifiedlocationandgeneratethefollowingclient-sideartifacts:

com\binildas\apache\axis\AxisEndToEnd\HelloWebServiceBindingStub.java

webservicebindingsampleAxis-basedstubs,

generatingcom\binildas\apache\axis\AxisEndToEnd\IHelloWeb.java

com\binildas\apache\axis\AxisEndToEnd\MyConsumerService.java

com\binildas\apache\axis\AxisEndToEnd\MyConsumerServiceLocator.java

TheClientJavaclasscanbewrittenagainstthesegeneratedfilesasfollows:

publicclassClient

{

privatestaticStringwsdlUrl="http://localhost:8081/services/

HelloWebService/main.wsdl";

privatestaticStringnamespaceURI="http://AxisEndToEnd.

axis.apache.binildas.com";

privatestaticStringlocalPart="MyConsumerService";

protectedvoidexecuteClient(String[]args)throwsException

{

{

MyConsumerServicemyConsumerService=null;

IHelloWebiHelloWeb=null;

if(args.length==3)

{

myConsumerService=newMyConsumerServiceLocator(args[0],new

QName(args[1],args[2]));

}

else

{

myConsumerService=newMyConsumerServiceLocator(wsdlUrl,new

QName(namespaceURI,localPart));

}

iHelloWeb=myConsumerService.getHelloWebService();

}

publicstaticvoidmain(String[]args)throwsException

{

Clientclient=newClient();

client.executeClient(args);

}

}

TobuildtheentireAxisclientcodebase,assumingthattheServiceMixisupandrunning,changedirectorytoch10\ServiceMixHttpBinding\03_AxisClient,whichcontainsabuild.xmlfile.Executeantasshownasfollows:

cdch10\ServiceMixHttpBinding\03_AxisClient

ant

ThiswillgeneratetherequiredAxisclient-sidestubsandcompiletheclientclasses.Nowtoruntheclient,executethefollowingcommand:

antrun

SummaryWestartedthischapterbyintroducingtheservicemix-httpJBIcomponent.ThenwelookedatthesamplesofbindingwebservicestoESBusingtheservicemix-httpbindingcomponent.Bydoingso,wehave,infact,implementedacompletefunctionalwebservicesgatewayattheESB.

Alotoftimes,weutilizethispatterntoexposeusefulwebserviceshosteddeepinsideyourcorporatenetworksprotectedbymultiplelevelsoffirewall.Whenwedoso,thewebservicesgatewayistheaccesspointforanyexternalclient.Itshouldmocktheactualwebservicenotonlyinprovidingthefunctionalitybutalsoinexposingthewebservicescontract(WSDL).Now,doyouwanttoimprovetheQOSattributesofyourwebservice?

ThenextchapterwilltakeyouthroughasimilarexercisebydemonstratinghowtoaccessyourHTTP-basedwebservicesthroughanMOMchannellikeJMS.

Chapter11.AccessWebServicesUsingtheJMSChannelWebservicesaregreatenablersfortheSOAarchitectureswhichareneutraloftheunderlyingplatformandtechnology.Itcanalsopenetratethroughthecorporatefirewalls,thusactingasaremotecontrolswitch.However,attimes,wemaywanttoguaranteeafewQOSaspectsofthisserviceinvocation.ThereliabilityoftheHTTPtransportchannelmaynotbesufficientforscenariossuchasthis.Inthischapter,wewilllookathowJavaJMS,whichisaplatform-dependentmessagingtechnology,canincreasetheQOSfeaturesofthewebservices.

Sowewilllookatthefollowinginthischapter:

WhatisJMS?

Reliabilityandwebservices.

SOAPversusJMS.

JMSsupportingcomponentsinServiceMix.

AprotocolbridgetoconvertHTTPtoJMS.

AsampledemonstratingthebindingofwebservicestoaJMSchannel.

JMSJMSdefinesthestandardforareliableenterprisemessaging,alsoreferredtoasMOM.Enterprisemessagingprovidesareliableandflexiblemechanismforthelooselycoupled(asynchronous)exchangeofcriticalbusinessdataandeventsthroughoutanenterprise.TheJMSAPIaddstothisacommonAPIandaproviderframeworkthatenablesthedevelopmentofportable,message-basedapplicationsintheJavaprogramminglanguage.

TheJMSAPIenhancesJ2EEinthefollowingways:

Message-drivenbeansbasedontheJMSenabletheasynchronousconsumptionoftheJMSmessages.

JMSmessageexchangecanparticipateintheJavaTransactionAPI(JTA)transactions.

TheJCAinterfacesallowJMSimplementationsfromdifferentvendorstobeexternallypluggedintoaJ2EEenvironment.

SinceMOMdefinesthebackboneformanyESBimplementations,JMSplaysacriticalroleinJava-basedESB.

WebServiceandJMSReliabilityisoftheprimeconcernincriticalapplications,especiallyininteractionsinvolvingfinancialtransactions.Considerthescenariooffundtransferwherewedebitoneaccountandcreditanotheraccountwiththesameamountofmoney.Wecannotalloweitherofthesetransactionstofailor

todebittwiceinanaccountasaresultofmessageduplications.UnreliabletransportchannelslikeHTTPandnon-reliabilityinmessagedeliverywillimpedethecorrectnessofthemissioncriticaltransactions.ThisiswherethealternativestoSOAPoverHTTP,whichisbeingexplored.

SpecificationsforWebServiceReliableMessagingThewebservicesworlddefinestwospecificationstointroducereliability,namely:

WS-Reliability.

WS-ReliableMessaging.

BoththesespecificationsuseSOAPheaderstoexchangemessagegroupingandcorrelationinformationbetweenaconsumerandaprovidersothatthereliabilitylayercanguaranteethefollowingqualityconcerns:

Guaranteeddelivery.

Onceandonlyoncedelivery.

Messageordering.

WebServicesReliability(WS-Reliability)isaSOAP-basedprotocolwiththepurposeofexchangingSOAPmessageswithguaranteeddelivery,noduplicates,andguaranteedmessageordering.WS-ReliabilityisdefinedasSOAPheaderextensionsandis,infact,independentoftheunderlyingprotocolused.Atthesametime,thisspecificationcontainsa

bindingtoHTTP.ThereliablemessageprotocolisabstractedfromthecommunicationbetweenasendingReliableMessagingProcessor(RMP)andareceivingRMP.HencetheSOAPintermediariesdonotplayanyactiveroleinthereliabilitymechanisms.WS-ReliabilitywaspublishedinJanuary2003byHitachi,Oracle,Sonic,andSunMicrosystems,andthensubmittedtotheOASISWebServicesReliableMessagingTechnicalCommittee.

TheWebServicesReliableMessaging(WSRM)protocolisbasedontheWS-ReliablemessagingspecificationandwaspublishedinMarch2003bysoftwaremajorsincludingBEA,IBM,Microsoft,andTibco.WSRMalsoworkssimilartowebservicesreliability.Insteadofagroup,theWSRMhasthenotionofasequencetoensuremessagereliabilityconcerns.

Dependinguponthecriticalityofthebusinessapplications,varyingordersofreliabilitymightberequiredandWSRM-basedproductswillsupportthis.However,boththeWSRMspecificationsaresilentonmanyoftheaspects.Afewofthesearelistedasfollows:

Undeliverablemessages—Nodefinitionofdeadletterqueue.

Messagepriority.

Messagepersistence.

TheaboveaspectsareoutofthescopeoftheWSRMspecifications,eventhoughtheimplementationsofreliablemessagingneedstoaddressalloranyofthemdependingupontheorderofreliabilityrequired.TraditionalJMS-basedMOMprovideswaystoaddresstheaboveconcerns,whichwecan

leverageeveninnormalwebservices.ItisinthiscontextthatweneedtolookintocombiningtheMOMinfrastructurewithSOAP(WebServices),togetthebestofboththeworlds.

SOAPoverHTTPversusSOAPoverJMSSOAPistransportindependentandcanbeboundtoanytransport.TheusualtransportbindingforSOAPisHTTPandSOAPoverHTTPiswhatweusuallylookatasinteroperable.HTTPbelongstotheapplicationlayerofboththeOpenSystemInterface(OSI)model(layer7)andtheInternetProtocol(IP)suite(layer4or5).

ThefollowingWSDLsnippetshowswhatforaHTTPboundSOAPmessagelookslike:

<wsdl:definitions>

<wsdl:bindingname="HelloWebServiceSoapBinding"

type="impl:IHelloWeb">

<wsdlsoap:bindingstyle="document"

transport="http://schemas.xmlsoap.orgsoaphttp">

<wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebServiceSoapBinding"

name="HelloWebService">

<wsdlsoap:address

location="http://localhost:8080/

AxisEndToEnd/services/HelloWebService">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

DuetothemanyQOSfeaturesofJMS,SOAPoverJMSoffersmorereliableandscalablemessagingsupportthanSOAPoverHTTP.BybuildingontopoftheJMS,SOAPoverJMSsupportstwomessagingstyles—one-wayrequeststyleandtwo-wayrequestandresponsestyle.One-wayrequestmessagingallowsawebserviceclienttounblockitselfwhentherequestmessagereachesaJMSqueueortopic.Two-wayrequestandresponsemessagingblocksawebserviceclientuntiltherequestreachestheserverandaresponsemessageisreceivedbackattheclient-side.AsampleWSDLsnippetisshownisshownasfollows:

<wsdl:definitions>

<wsdl:bindingname="HelloWebServiceSoapBinding"

type="impl:IHelloWeb">

<wsdlsoap:bindingstyle="document"

transport="http://schemas.xmlsoap.org/soap/jms">

<wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebServiceSoapBinding"

name="HelloWebService">

<wsdlsoap:addresslocation="jms:/queue?

destination==jms/queue&amp;

connectionFactory=weblogic.jndi.

WLInitialContextFactory">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

ButthedownsideisthatSOAPoverJMSisnotyetstandardizedandhencemaynotbeinteroperableacrossplatforms.ThisisbecauseJMSisnotan"over-the-wire"protocol.Instead,JMSisaJavaAPIwhichrequiresaclientto

JMSinServiceMixServiceMixprovidesuswiththeservicemix-jmscomponentwhichmakesiteasytobindtheendpointstotheJMSchannel,bothintheconsumerandproviderroles.Hence,beforewelookintothedetailsonhowtobindthewebservicestotheJMStransport,wewilllookatconfiguringtheservicemix-jmscomponent.

useaJMSproviderlibrary(ajarfile)providedbythevendoroftheJMSserviceprovider.ThisisanalogoustorequiringaJDBCdriversimilartoclasses12.jarfromOracleforconnectingtoanOracleserverfromajavaapplication.Theactual"over-the-wire"protocoltobeusedunderthecoverswithintheJMSproviderlibraryisnotdefinedandisleftopenforvendorstohavetheirownimplementations.Theinteroperabilityisnoteasyevenifweconsiderthejavaworldalone.Thatis,ifwehaveanIBMWebsphereJMSproviderandaclientprogramfromwithintheBEAWeblogicapplicationserverneedtoaccesstheJMSserver.Eventhoughboththeplatformsarejava-based,theintegrationmightnotbestraightforwardduetotheJMSimplementationclashes.Moreover,JMSbeinganAPIdoesn'taskvendorstoimplementanyadditionalservicesanddoesn'tstandardizethedatastructureexchanged.However,JMSstillisaviablemechanismtoMOMthatenableswebservices.

Servicemix-jmsTheservicemix-jmscomponentsallowyoutosendandreceiveJMSmessages.Theservicemix-jmscomponentsassumethatthenormalizedmessagetheyaregivenisreadyformarshallingintooroutofJMS.Hence,theydon't,bydefault,trytoimplementaSOAPstackorperformanycomplexmessagetransformationotherthantomapnormalizedmessagestoJMSorviceversa.However,itispossibletospecifytheSOAPenvelopedpayloadasmessagessothatservicemix-jmscanperformwrappingandunwrappingofpayloadfromwithintheSOAPenvelope.

Afewofthefeaturesofservicemix-jmsareasfollows:

StandardJBI-compliantbindingcomponent.

SupportslightweightandXBean-baseddeployments.

SupportsSOAP1.1and1.2support.

SupportsMIMEwithattachments.

SupportsWS-Addressing.

SupportforallMEPsintheconsumerortheproviderrole.

ConsumerandProviderRolesservicemix-jmscanbeconfiguredbothasaconsumerandaproviderofservices.Similartoservicemix-http,theserolesarewithrespecttotheNMRoftheESB.Inotherwords,aconsumerroleimpliesthatthecomponentisaconsumertotheNMRwhereasaproviderroleimpliesthattheNMRistheconsumertothecomponent.Basedontheseroles,theNMRwilltakeresponsibilityofanyformatorprotocolconversionsfortheinteractingcomponents.YoucanrefertotheConsumerandProviderRolessectioninChapter10tounderstandmoreonthecontractandresponsibilityoftheseroles.

servicemix-jmsXBeanConfigurationTheservicemix-jmscomponentsupportstheXBean-baseddeployment.Sincetheservicemix-jmscomponentcanbeconfiguredinboththeconsumerandproviderroles,wehavetwosetsofconfigurationparametersforthecomponent.Letuslookintothemainconfigurationparameterslistedasfollows:

servicemix-jmsasconsumer:Asampleservicemix-jmsconsumercomponentconfigurationisshownasfollows:

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"soap="true"

targetService="test:pipeline"

defaultMep="http://www.w3.org/2004/08/wsdl/in-only"

destinationStyle="queue"jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory"/>

Thefollowingtablelistsoutthemainattributesusedtoconfigureservicemix-jmscomponentintheconsumerrole:

AttributeName

Type Description MandatoryorNot

service

QName

Servicenameofproxyendpoint. Mandatory.

endpoi

String Endpointnameofproxyendpoint. Mandatory.

point

role String Whetheraconsumeroraprovider. Mandatory.Valueshouldbeconsumer.

soap

boolean

Ifitistrue,thecomponentwillparsetheSOAPenvelopeandpassthecontentstotheNMR.

NotMandatory.Defaultvalueisfalse.

targetService

QName

Servicenameofthetargetendpoint. NotMandatory.Defaultisthevalueoftheserviceattribute.

defaultMEP

URI TheMEPURIbywhichclientsinteractwiththeconsumercomponent.

NotMandatory.

destinationStyle

String IndicatesthedestinationtypeusedwiththejmsProviderDestinationName.

NotMandatory(unlessjmsProviderDestinationNameisused).

jmsPro

String ThetargetJMSdestination(QueueorTopic)willbecreatedbytheJMSprovider.

NotMandatory(eitherofdestination,

Provider

DestinationNa

me

willbecreatedbytheJMSprovider. destination,jndiDestinationNameorjmsProviderDestinationNameismandatory).

connectionFactory

javax.jms.ConnectionFactory

TheconnectionFactoryistobeused.InsteadaJNDIconfigurationcanbeprovidedusingjndiConnectionFactoryName.

NotMandatory.

useMsgIdInResponse

boolean

TruevalueindicatesthattheJMScorrelationidwillbesettotheidoftheJMSrequestmessage—ifitisfalse,anartificialcorrelationidwillbeusedinstead.

NotMandatory(inwhichcasethedefaultbehaviouristousethemessageexchangeidasthecorrelationid).

Inthesampleconfigurationlistedearlier,ifaclienthastosendamessagetotheNMRithastoplacethemessageinthequeuequeue/A.SincetheMEPisin-only,theclientwillnotreceiveanyresponse.Hence,ifaclienthastosendanormalrequest-responsetotheNMR,thenweneedtouseadditionalMEPconversionbridges(Note:thetargetServiceinthesampleconfigurationwhichisanMEPconversionpipeline,whichwillbedemonstratedinanexampleinthischapter).Eventhatisnotsufficientsinceweneedamechanismtoco-relaterequestandresponsemessages.ThiscanbedonebysettingtheJMScorrelationid(eventhoughwedon'tdemonstratethisinoursample).

servicemix-jmsasprovider:Asampleservicemix-jmsprovidercomponentconfigurationisshownasfollows:

<jms:endpointservice="test:MyProviderService"

endpoint="myProvider"role="provider"soap="true"

destinationStyle="queue"jmsProviderDestinationName="queue/B"

connectionFactory="#connectionFactory"/>

Thefollowingtablelistsoutthemainattributesusedtoconfiguretheservicemix-jmscomponentintheproviderrole:

AttributeName

Type Description MandatoryorNot

service QName Servicenameoftheexposedendpoint. Mandatory.

endpoint

String Endpointnameoftheexposedendpoint. Mandatory.

role String Whetheraconsumeroraprovider. Mandatory.Valueshouldbeprovider.

soap boolean Ifitistrue,thecomponentwillparsetheSOAPenvelopeandpassthecontentstotheNMR.

NotMandatory.Defaultvalueisfalse.

destinati String Indicatesthedestinationtypeusedwith NotMandatory(unlessjmsProvider

onStyle thejmsProviderDestinationName. DestinationNameisused).

jmsProv

iderDestinationName

String ThetargetJMSdestination(Queueor

Topic)willbecreatedbytheJMSprovider.

NotMandatory(eitherof

destination,jndiDestinationName,orjmsProviderDestinationNameismandatory).

connectionFactory

javax.jms.ConnectionFactory

TheconnectionFactoryistobeused.InsteadaJNDIconfigurationcanbeprovidedusingjndiConnectionFactoryName.

NotMandatory.

servicemix-jmsLightweightConfigurationInadditiontotheXBean-basedconfigurationlistedearlier,servicemix-jmscanalsobedeployedbasedonthelightweightmodeforuseinanembeddedServiceMix.Theconfigurationwouldbeasfollows:

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="true"targetService="test:pipeline"

defaultMep="http://www.w3.org/2004/08/wsdl/in-only"

destinationStyle="queue"

jmsProviderDestinationName="queue/A"connectionFactory

="#connectionFactory">

<jms:endpointservice="test:MyProviderService"

endpoint="myProvider"role="provider"soap="true"

destinationStyle="queue"jmsProviderDestinationName="queueB"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

ProtocolBridgeAprotocolbridgeisanintegrationpatterntoconnectbetweentwodifferentprotocols.Forexample,HTTPandJMSaretwodifferenttransportprotocols.Iftherewasawaytobridgethesetwo,wecouldleveragethebestofbothworlds(openstandardnatureofHTTPandreliabletransportfeatureofJMS).Typically,itisnotstraightforwardtoconnecttwodifferentprotocolsandexchangeinformation.Weneedtoconnectindividual,correspondingchannelsspeakingdifferentprotocolsinthemessagingsystem.Thisisdemonstratedinthefollowingfigure:

Aprotocolbridgecanbeviewedasacombinationofchanneladapters.Anadaptercanfunctionasaclienttothemessagingsystem.Withtheclientrole,theadaptorcaninvokeapplicationfunctionsthroughtheapplicationsuppliedinterfaces.ThusaHTTPchanneladaptercanbeusedtoaccesstheHTTPservice

andpublishmessagesonaJMSchannel.Similarly,thesameadaptercanalsoreceivemessagesfromtheJMSchannelandinvokethefunctionalityovertheHTTPservice.

Alongthoselines,wecannowthinkofawebserviceadaptertotranslatebetweentheHTTP-basedwebserviceandtheJMS-basedmessagingsystem.Bydoingso,theSOAPformattedmessagescanberoutedthroughthetraditionalHTTPchannelthroughfirewallsovertheInternet,andalsothroughthemessagingchannelovertheintranetforaccessbyinterdepartmentalsystems.

Forexample,youcanthinkofascenariowhereanenterpriseprovidesa"ProductQuery"serviceoran"InventoryUpdate"service.SuchservicescanbeaccessedbyinterdepartmentalorLOBsystemssuchasthe"OrderEntry"systemor"Shipping"systemoverJMS.IftheenterprisewantstoexposetheseservicesoverthefirewallforB2Binteractionwithotherenterprises,theycandosointheSOAPoverHTTPstyleofinteraction.Forboththesetwotypesofinteraction,wedon'tneedtodefinetwoseparateservices.Instead,usinganadapter,thesameservicecanbemadeaccessiblethroughmultiplechannels.ThewebservicesgatewayprovidedbytheIBMWebsphereApplicationserverisafirstclassexampleofawebserviceadapter.

WebServiceintheJMSChannelBindingSampleWewillnowlookatacompletesampleofhowtobindawebserviceusingtheJMSchanneltoServiceMix.Whiledoingso,wewillalsoseehowtousethe

ApacheAxisclient-sideAPIstosendarequesttoandreceivearesponsefromthewebservice,throughtheJMSchannelratherthanthenormalHTTPchannel.WemaynotconfigurealloftheQOSfeaturesfortheJMSproviderheresuchastransaction,messagepersistence,orguaranteeddelivery.MostofthemareoutsidethestandardJ2EEconfigurationsandhavetobedoneattheJMSprovider-levelbasedonthevendor-specificmechanisms.SincethisbookisaboutJBIandServiceMixandnotJMS,wewillconcentrateonlyonthebindingpart.OncewearesuccessfulinbindingthewebservicetoJMS,thenenablingotherQOSfeaturesissimilartowhatwedointhenormalJMSconfigurations.

ServiceMixComponentArchitecturefortheJMSWebServiceWewillfirstlookatthetechnicalarchitectureforthewholecomponentsetuptoseehowwecanroutemessagesthroughvariousServiceMixcomponents.Themajorpartiesorrolestakingpartintheexchangeareasfollows:

Externalclient(sendingrequestandacceptingresponse).

JMSconsumer(requestqueueforclient).

Pipelinebridge.

HTTPprovider.

Externalwebservice.

JMSprovider(responsequeueforclient).

Asweknow,allthecomponentsareboundappropriatelytotheNMRandallthemessageexchangestakeplacethroughtheNMR.Thefollowingfigureshowsthecomponentarchitecture:

Asshownintheabovefigure,whentheclientsendsamessage,themessage-flowthroughtheNMRthroughvariousJBIcomponentsaremarkedbynumbersinsequence.YoumaynotethedynamicsofthePipelinecomponentinthepreviousfigure.Here,thePipelinewillsendtheinputmessageinanIn-OutMEPtotheHTTPProviderdestinationandtheninturnforwardtheresponseinanIn-OnlyMEPtotheJMSProvider.

Anaspecttonoticeintheabovearchitectureisthatthewholeinteractionisinarequest-responsestylefromtheconsumer(client)perspective.However,atthetransport-levelweimplementthisasacombinationofaIn-Onlyrequestanditscorrespondingresponse.

Letusnowsetuptheindividualcomponentsshowninthetechnicalarchitecture

figure.

DeploytheWebServiceAsafirststep,ifyouhaven'tdoneitbefore,editexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter),andchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesthedetailedstepstobuildandrunthesamples.

Wehaveasimplewebserviceinthecodebasepresentinthefolderch11\WebServiceInJmsChannel\01_ws.Todeploythewebservice,firstchangethedirectorytoch11\WebServiceInJmsChannel\01_wsandexecuteantasshownasfollows:

cdch11\WebServiceInJmsChannel\01_ws

ant

Thewebservicewillbecompletelybuiltandthewarfilecanbefoundinthefolder:ch11\WebServiceInJmsChannel\01_ws\dist\AxisEndToEnd.wa

r.

Todeploythewebservice,justdropthiswarfileintoyourfavoritewebserver'swebappsfolderandrestartthewebserver,ifnecessary.

Nowtomakesurethatyourwebservicedeploymentworksfine,wehaveprovidedtwotestclients.Toinvokethetestclientrunthefollowingcommands:

cdch11\ServiceMixHttpBinding\01_ws

antrun

and/or

anttest

WecanalsocheckthewebservicedeploymentbyaccessingtheWSDLfromthefollowingURL:http://localhost:8080/AxisEndToEnd/services/HelloWebSe

rvice?WSDL

Thetop-levelfolder,thatisch11\WebServiceInJmsChannel,willhaveasinglebuild.xmlfilewhichwillbuildallthesubprojectsinasinglego.Tobuildtheentiresample,changedirectorytothisfolderandexecuteantasfollows:

cdch11\WebServiceInJmsChannel

ant

XBean-basedservicemix-jmsBindingForXBean-baseddeploymentofservicemix-jms,ourxbean.xmlfilelookslikethefollowing:

<?xmlversion="1.0"encoding="UTF-8"?>

<beansxmlns:jms="http://servicemix.apache.org/jms/1.0"

xmlns:test="http://AxisEndToEnd.axis.apache.binildas.com">

<classpath>

<location>.</location>

</classpath>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"value="tcp://localhost:61616">

<bean>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"soap="true"

targetService="test:pipeline"

defaultMep="http://www.w3.org/2004/08/wsdl/in-only"

destinationStyle="queue"jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpointservice="test:MyProviderService"

endpoint="myProvider"role="provider"soap="true"

destinationStyle="queue"jmsProviderDestinationName="queueB"

connectionFactory="#connectionFactory">

<beans>

Perhaps,youmighthavenoticedthefactthatfortheaboveconsumerrolethetargetServiceisnottheactualwebservice,butapipelinewhichisexplainednext.

XBean-basedservicemix-eipPipelineBridgeThepipelinecomponentisanintegrationbridgebetweenanIn-Only(orRobust-In-Only)MEPandanIn-OutMEP.ByreceivinganIn-OnlyMEPbythepipeline,wewillsendtheinputmessageinanIn-OutMEPtothetransformerdestinationandtheninturnforwardtheresponseinanIn-OnlyMEPtothetargetdestination.ThepipelineisastandardEIPcomponentandhenceisavailablereadilyasastandardJBIEIPcomponentinServiceMix.

ThepipelineEIPcomponentcanbeconfiguredusingXBeananddeployed.Theconfigurationxbean.xmlfileisasshownasfollows:

<beansxmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:test="http://AxisEndToEnd.axis.apache.binildas.com">

<classpath>

<location>.</location>

</classpath>

<eip:pipelineservice="test:pipeline"endpoint="pipeline">

<eip:transformer>

<eip:exchange-targetservice="test:IHelloWebService">

<eip:transformer>

<eip:target>

<eip:exchange-targetservice="test:MyProviderService">

<eip:target>

</eip:pipeline>

</beans>

XBean-basedservicemix-httpProviderDestinationWenowrequireanIn-OutMEP-basedtargettransformerasthemessagedestination.Sinceourtargetserviceisawebservice,itmakessensetouseaservicemix-httpcomponentintheproviderroletopointtotheexternalwebservice.Thexbean.xmlconfigurationisasfollows:

<beansxmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:test="http://AxisEndToEnd.axis.apache.binildas.com">

<classpath>

<location>.</location>

</classpath>

<http:endpointservice="test:IHelloWebService"

endpoint="HelloWebService"role="provider"

locationURI="http://localhost:8080/AxisEndToEnd/

ervices/HelloWebService"soap="true"soapAction=""

wsdlResource="http://localhost:8080/AxisEndToEnd/

services/HelloWebService?WSDL">

<beans>

DeployingtheSampleandStartingServiceMixTodeploytheServiceMixsample,wehavethefollowingservicemix.xml:

<?xmlversion="1.0"encoding="UTF-8"?>

<beansxmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://AxisEndToEnd.axis.apache.binildas.com">

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"value="classpath:servicemix.properties"

>

<bean>

<sm:containerid="jbi"MBeanServer="#jmxServer"

useMBeanServer="true"createMBeanServer="true"rootDir="./wdir"

installationDirPath="./install"deploymentDirPath="./deploy"

flowName="seda">

<sm:activationSpecs>

</sm:activationSpecs>

</sm:container>

</beans>

TobringupServiceMix,changedirectorytoch11\WebServiceInJmsChannelandbringuptheServiceMixcontainer.

cdch11\WebServiceInJmsChannel

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

TestWebServiceUsingJMSChannelTotestthewebservicedeployedsendingmessagesthroughJMSchannel,wewillhavetwoapproachesasfollows:

TestusingJMSclient—documentstyle:Thisapproachissimpleandstraightforward.WecancreateasimpleJMSclientwhichcanplaceaSOAPrequestdocumentintheinputqueue.Thesameclientwillalsolistentoanoutputqueuesothatwhenever(withinatimelimit)aresponsemessageisreceivedbackinthisqueuethentheclientcanconsumeit.

publicclassJMSClient

webservicetesting,documentstyle{

publicstaticStringMESSAGE_1="<?xmlversion=\"1.0\"

encoding=\"UTF-8\"?>SOAPMessage...";

privatestaticfinallongWAIT_TIME=51000L;

publicstaticvoidmain(String[]args)throwsException

{

ActiveMQConnectionFactoryfactory=new

ActiveMQConnectionFactory("tcp://localhost:61616");

ActiveMQQueuepubTopic=newActiveMQQueue("queue/A");

ActiveMQQueuesubTopic=newActiveMQQueue("queue/B");

Connectionconnection=factory.createConnection();

Sessionsession=connection.createSession(false,

Session.AUTO_ACKNOWLEDGE);

MessageProducerproducer=session.createProducer(pubTopic);

MessageConsumerconsumer=session.createConsumer(subTopic);

connection.start();

producer.send(session.createTextMessage(MESSAGE_1));

TextMessagetextMessage=(TextMessage)consumer.receive(1000

10);

if(textMessage==null)

{

System.out.println("Responsetimedout.");

}

else

{

System.out.println("Responsewas:"+textMessage.getText());

}

System.out.println("Closing.");

connection.close();

}

}

TheJMSClientisplacedinthefolderch11\WebServiceInJmsChannel\03_BindJms\src.Theclientclasswasalreadycompiledwhenwebuiltthefullproject.Torunthetestclient,changedirectorytoch11\WebServiceInJmsChannel\03_BindJmsandexecuteantasfollows:

cdch11\WebServiceInJmsChannel\03_BindJms

antrun

TestusingAxisclient—RPCstyle:Inthepreviousexample,wefollowedapuredocument-orientedapproachtoinvokethewebserviceandgetbacktheresponse.DuetothefactthatthetransportchannelisJMSwhichisdetachedandasynchronous,wemaynotbeabletochangethestylefullyfromthedocument-orientedapproach.However,wecanmaketheinvocationclosetoanRPCstylebyusingtheApacheAxisserviceandcallingobjects.

WeneedtohavemultipleartifactstoinvokethewebserviceinRPCstyle,andtheyarelistedhereindetail:

JMSTestClientRPCWebService.java:Thisisthemainclientclassusedtoinvokethewebservice.Thisclassisplacedinthech11\WebServiceInJmsChannel\05_AxisClient\src\com\binildas\apache\a

xis\AxisEndToEndfolder.

publicclassJMSTestClientRPCWebService

{

publicstaticvoidmain(Stringargs[])throwsException

{

org.apache.axis.client.ServiceaxisServiceObj=new

org.apache.axis.client.Service();

org.apache.axis.client.CallaxisCall=

(org.apache.axis.client.Call)axisServiceObj.createCall();

axisCall.setOperationName("hello");

axisCall.addParameter("in0",org.apache.axis.

encoding.XMLType.XSD_STRING,javax.xml.rpc.ParameterMode.IN

);

axisCall.setReturnType(org.apache.axis.encoding.

XMLType.XSD_STRING);

org.apache.axis.client.Transporttransport=new

org.apache.axis.client.Transporttransport=new

JMSTransportForAxis();

axisCall.setTransport(transport);

axisCall.setProperty("REQUEST_QUEUE","queue/A");

axisCall.setProperty("RESPONSE_QUEUE","queue/B");

Stringres=(String)axisCall.invoke(newObject[]

{"Binil"});

System.out.println("res:"+res);

}

}

Aswecanseeinthecodelisting,wefirstcreateanAxisCallinstanceandsettheoperationname(whichisthemethodnameoftheremotewebservice)andtheinputparameterstoinvoketheoperation.WealsoneedtosetthereturntypedetailssothattheCallinstancecanunmarshallanyreturntyperecievedfromthetransportchanneltothesuitableJavatype.

ThenextimportantstepissettingthetransportclassfortheCallobject.Here,wesetaninstanceofJMSTransportForAxis,whichprovidesthegatewaytothetransportchannel.

JMSTransportForAxis.java:ThisclassextendstheApacheAxisTransportclass:

publicclassJMSTransportForAxisextendsorg.apache.axis.

client.Transport

{

publicJMSTransportForAxis()

{

transportName="JMSTransportForAxis";

}

}

client-config.wsdd:Thenextimportantpieceistheclient-config.wsdd,whichshouldbethereintheclasspathwhileweinvoketheJMSTestClientRPCWebServiceclass.Thisconfigurationisplacedinch11\WebServiceInJmsChannel\05_AxisClient\config.

<?xmlversion="1.0"encoding="UTF-8"?>

<deploymentname="defaultClientConfig"

xmlns="http://xml.apache.org/axis/wsdd/"

xmlns:java="http://xml.apache.org/axis/wsdd/providers/java">

<transportname="http"

pivot="java:org.apache.axis.transport.http.HTTPSender">

<transportname="local"

pivot="java:org.apache.axis.transport.local.LocalSender">

<transportname="java"

pivot="java:org.apache.axis.transport.java.JavaSender">

<handlername="JMSSender"

type="java:org.apache.axis.transport.jms.JMSSender">

<transportname="JMSTransport"pivot="JMSSender">

<handlername="CustomJMSSender"

type="java:com.binildas.apache.axis.AxisEndToEnd.JMSSender"

>

<transportname="JMSTransportForAxis"pivot=

"CustomJMSSender">

<deployment>

Thelinestobenotedfromtheaboveconfigurationarereproducedasfollows:

<handlername="CustomJMSSender"

type="java:com.binildas.apache.axis.AxisEndToEnd.JMSSender"

>

<transportname="JMSTransportForAxis"pivot=

"CustomJMSSender">

IfweobservetheJMSTransportForAxisclass,wecanseethatthevalueofthesuperclass(Transport)field(transportName)issetas"JMSTransportForAxis".Intheclient-config.wsdd,wethenpivotCustomJMSSenderagainstJMSTransportForAxisvalue.Now,weagainmaptheCustomJMSSendertoacustomtransportsenderclassjava:com.binildas.apache.axis.AxisEndToEnd.JMSSender

JMSSender.java:ThisistheclasswheretheactualtransportplumbinghappensandthiscallisnotmuchdifferentfromtheJMSClientclasswealreadysawintheprevioustestinthesensethatwewillhaveaninputandanoutputqueuetoplacearequestandtoreadanyresponse.

publicclassJMSSenderextendsorg.apache.axis.handlers.

BasicHandler

{

publicvoidinvoke(org.apache.axis.MessageContextmsgContext)

throwsorg.apache.axis.AxisFault

{

try

{

webservice,classesJMSSender.javaActiveMQConnectionFactory

factory=newActiveMQConnectionFactory("tcp://

localhost:61616");

ObjectrequestDestination=msgContext.

getProperty("REQUEST_QUEUE");

ObjectresponseDestination=msgContext.

getProperty("RESPONSE_QUEUE");

ActiveMQQueuepubTopic=newActiveMQQueue((String)

requestDestination);

ActiveMQQueuesubTopic=newActiveMQQueue((String)

responseDestination);

Connectionconnection=factory.createConnection();

Sessionsession=connection.createSession(false,

Session.AUTO_ACKNOWLEDGE);

Sessionsession=connection.createSession(false,

Session.AUTO_ACKNOWLEDGE);

MessageProducerproducer=session.createProducer(pubTopic);

MessageConsumerconsumer=session.createConsumer(subTopic);

connection.start();

StringreqSOAPMsgString=msgContext

getRequestMessage().getSOAPPartAsString();

producer.send(session.createTextMessage(reqSOAPMsgString));

TextMessagem=(TextMessage)consumer.receive(1000*10);

StringrespMessageStr=null;

if(m==null)

{

System.out.println("Responsetimedout.");

}

else

{

respMessageStr=m.getText();

System.out.println("Responsewas:"+respMessageStr);

}

System.out.println("Closing.");

connection.close();

org.apache.axis.MessagerespSoapMessage=new

org.apache.axis.Message(respMessageStr);

msgContext.setResponseMessage(respSoapMessage);

}

catch(Exceptione)

{

throwneworg.apache.axis.AxisFault("failedSend",e);

throwneworg.apache.axis.AxisFault("failedSend",e);

}

}

}

Thepreviousprojectbuildhasalreadybuiltallthesubprojects,includingtheonecontainingalltheaboveclientclasses.So,torunthisclient,weneedtochangefoldertoch11\WebServiceInJmsChannel\05_AxisClientandexecuteantasfollows:

cdch11\WebServiceInJmsChannel\05_AxisClient

antrun

SummaryMOMincludingJMSisagreatenablerforreliablecommunicationbetweencomponents,especiallywhenyoudothatinalooselycoupled(asynchronous)manner.JMSprovidestherequiredAPIsandprovider-levelSPIsforJavacomponentstointeractthroughMOM.Combiningthepowerofmessagingoverareliablechannelalongwiththeinteroperabilityofwebservicesprovidesusagreaterflexibilitywithconfidenceinmessagingcharacteristics.WebservicesoverJMSarepositionedinthisspaceanditisnothingnewsincewehavebeendoingthatformanyenterpriseclasstransactions.ThenewthinghereistheendlesspossibilitiesprovidedbytheESBarchitecturewhencombinedwithtestedandprovenEAIpatterns.Thisisdemonstratedinthischapterwithsamples.Andkeepreading—youaregoingtoseemorepracticalusagesoftheESBarchitecturesuchaswebserviceversioninginthecomingchapters.

Chapter12.JavaXMLBindingusingXStreamWhiletheJavaprogramminglanguageprovidesusameanstowriteportablecode,XMLcanbeusedtodefineportabledata.WeuseXMLextensivelytoformatdatainSOA-basedarchitectures.Moreover,todayallnewgenerationplatforms,frameworks,andevenlegacyplatformssuchasCOBOLandMainframesexhibitsupportforXMLformatteddata.

ServiceMixisallaboutSOIandhenceitisalsoconcernedwithportabledata.Naturally,theformatofdatainsidetheNMRisXML.AnotheraspectisthatServiceMixisaJava-basedJBIframework.Hence,thedevelopersneedtowritecodeinJava,whethertheyareSEsorBCs.ItisinthiscontextthattherelationshipbetweenJavaandXMLintheServiceMixcontextneedsattention.

ThischapterwillprovideabriefintroductiontoJavaXMLbindingandtotheconceptsandtechnologiesthatitemploys.

Sowewillcoverthefollowinginthischapter:

JavaXMLbindingingeneral

JavaXMLbindingframeworksincludingXStream

XStreamintegrationwiththeServiceMixESB

WorkingcodesampleshowingXStreaminactioninServiceMix

JavaXMLBindingJavaXMLbindingdealswithtransformingtheXMLinstancestotheJavainstancesandviceversa.EventhoughwecandothisbywritingJavacodefromscratchagainsttheXMLAPIs,todaywehavemultipletoolsandframeworkswhichwilldothesame.

TheabovefigureshowsatypicalscenariowemightcomeacrossinB2Binteractions.LeavetheadvancedvalidationsorCRUDoperationsonecandointheXMLdocumentsalone,weareinterestedinthemarshallingandunmarshallingfunctionalityoftheJAXB.XMListhede-factowireformatinSOAandSOI.IfweneedtoprocesstheXMLdatafromwithinourJavacomponents,wehavetodosomeformofXMLbinding.TheframeworkssuchasCastorandXMLBeansdoexactlythis.JAXBistheJavareferenceimplementationforJavaXMLbinding.Today,wehaveXStreamwhichwilldothesamefunctionalityquickly.Letusseehowthese

frameworksarerelevantintheJBIdiscussion.

JAXBJavaAPIforXMLBinding(JAXB)providesaconvenientwaytoprocessXMLcontentusingJavaobjectsbybindingitsXMLschematoJavarepresentation.JAXBprovidesanAPIandtherequiredtoolsetsthatautomatethemappingbetweentheXMLdocumentsandtheJavainstances.Thuswecanlistoutthemainfeaturesas:

UnmarshaltheXMLinstanceintoaJavainstance.

Access,update,andvalidatetheJavarepresentationagainstschemaconstraint.

MarshaltheJavainstanceoftheXMLcontentintotheXMLdocumentinstance.

XStreamXStreamisasimple,opensourcelibrarytoserializeJavaobjectstotheXMLandbackagain.Itislightweightinthesensethatitdoesn'trequiremuchconfigurationormappingfiles.XStreamhasagoodintegrationwiththeServiceMix.Infact,ServiceMixprovidesanXStreambackedAPIitselfnamedJavaSource.

ThemainfeaturesofXStreamarelistedasfollows:

Easeforuse:Ahigh-levelfacade-classcalledXStreamissuppliedwhichsimplifiesthecommonusecases.

Nomappingsrequired:Mostobjectscanbeserializedbyregisteringtheir

class.

Performance:XStreamissuitableforlargeobjectgraphsorsystemswithhighmessagethroughput.

Worksonnormalobjects:Serializesinternalfields,includingprivateandfinal.Supportsnon-publicandinnerclasses.Theclassesarenotrequiredtohaveadefaultconstructor.

Fullobjectgraphsupport:Duplicatereferencesencounteredintheobject-modelwillbemaintained.Supportscircularreferences.

IntegrateswithotherXMLAPIs:Byimplementingsuitableinterfaces,XStreamsupportsserializationdirectlytoorfromanytreestructureincludingXML.

LetusalsolookatasamplebindingusingXStream.ConsiderthefollowingtwoclassesnamelytheCustomerandtheContact:

publicclassCustomer

{

privateStringfirstName;

privateStringlastName;

privateContactphone;

}

publicclassContact

{

privateintcode;

privateStringnumber;

}

Now,ifyouhavetouseXStreamtoconverttheaboveentitiestoXML,thenfirstinstantiatetheXStreamfaçadeandcreatealiasesforyourcustomclassnamestoXMLelementnamesasshowninthefollowingcode:

XStreamxStream=newXStream();

XStreamxStream=newXStream();

xStream.alias("customer",Customer.class);

xStream.alias("contact",Contact.class);

Nowitisamatterofcreatingtheentitytree,populatingitsfields,andthencallingthetoXMLmethodinXStream.Thisisreproducedinthefollowingcode:

Customerbinil=newCustomer("Binil","Das");

binil.setPhone(newContact(91,"471-2700888"));

Stringxml=xStream.toXML(binil);

TheXMLoutputwilllooklikethis:

<customer>

<firstname>Binil</firstname>

<lastname>Das</lastname>

<phone>

<code>91</code>

<number>471-2700888</number>

</phone>

</customer>

ToreconstructtheobjecttreebackfromXMLiseasy,andisshownasfollows:

CustomerbinilBack=(Customer)

xstream.fromXML(xml);

ServiceMixandXStreamServiceMixhasgoodintegrationwithXStreamasa

mechanismforXMLtoJavabindingandviceversa.ThisismadepossibleinServiceMixbyexposingafewAPIs,themainonesarelistedasfollows:

org.apache.servicemix.jbi.messaging.DefaultMarshaler

org.apache.servicemix.components.util.xstream.XStreamMarshaler

org.apache.servicemix.components.util.xstream.XStreamSource

org.apache.servicemix.JavaSource

Therelationshipbetweentheseclasseswithcom.thoughtworks.xstream.XStreamisshowninthefollowingfigure:

Now,ifweneedtointegratewithXStreaminourcustomtransformationcomponents,wecandosobycreatinganinstanceofXStreamSource.

XStreamxStream=newXStream();

xStream.alias("ServiceParamTO",

ServiceParamTO.class);

xStream.alias("CustomerTO",CustomerTO.class);

//Registerotherclasses…

JavaSourceJavaSource=new

JavaSourceJavaSource=new

XStreamSource(payLoad,xStream);

Now,wejustsetthisinstanceofXStreamSourceastheinmessagetotheinOutmethodandsendthemessageexchange.

normalizedMessageIn.setContent(javaSource);

inOut.setInMessage(normalizedMessageIn);

sendSync(inOut);

Asyouknow,theNMRofServiceMixalwaysdealswiththenormalizedmessageformat,whichistheXMLformat.TherequiredplumbingwillbedonebytheXStreaminthebackground.

XStreaminaNormalizedMessageRouterSampleInChapter7,youhavelearnthowtocodeandbuildcustomcomponentstobedeployedintheServiceMixcontainer.ThereweusedanHttpInterceptorclasstointerceptthecontentsoftheJBIexchangeandprintthemoutontheconsole.WewillenhancethecodefromthatsampletodemonstratehowwecanintegrateXStreamwithotherJBIclassesinServiceMix.

SampleUseCase

IntheSOAscenarios,weusetheXMLformattedmessagestotransportpayloadacrossnodes.WhetherSOAPformattedornot,XMLprovidesaflexiblemechanismtotransportdata,whichcanbevalidatedifrequiredusingtheXMLschemas.Letusalsobuildoursamplearoundthis.Hence,wewillassumethatwehaveanexternalclientsendinganXMLpayloadtotheESB.Letusseehowwecaninteractwiththisdatainsidethebus.

Thisisdiagrammaticallyrepresentedinthefollowingfigure:

Thesampleusecasewillconsistofthefollowingcomponents:

HTTPClient:TheHTTPClientisaclientexternaltotheESBwhichinteractwiththeHTTPConnectorinsidetheESBtosendtherequestmessageandgettheresponseback.

HTTPConnector:TheHTTPConnectorisaServiceMixHttpConnectorcomponentconfiguredtolistentoaspecificport.AnymessagesarrivingattheHTTPConnectorwillbedirectedtothenextcomponentintheflow,namelytheHTTPInspector.

HTTPInterceptor:TheHTTPInterceptorisaServiceMixTransformComponent.Thiscomponent,asthenameimplies,willfirstinterceptthemessagecontents.TheXMLformattedmessagesentbytheHTTPClientwillbeinterceptedhere,andthenprintedouttotheconsole.WethenunmarshaltheXMLinstanceintoaJavainstanceusingtheXStream.Nextcomesthekeysequenceinthissample—wesettheJavainstanceintotheInOutofthemessageexchangeinthenextchainoftheinteraction,tobesenttothedestinationservice,XStreamInspector.

XStreamInspector:InXStreamInspector,wetrytoretrievebackthemessagecontentandprintittotheconsole.ThenXStreamInspectorsendsthesameXMLcontentbacktotheHTTPInterceptor.

Inthereversestreamflow,atHTTPInterceptorweagainprintoutthecontentreceivedfromtheXStreamInspectortotheconsole,andthensendbackthesameXMLtotheHTTPClient.

Thefollowingfigurelistshowthevariouscodeartifactsforthesampleareorganized:

CodeHTTPClientHTTPClientisanormalHTTPClientandiscodedinthefilech12\JavaXmlBinding\Client.html.ThiscomponentiscapableofsendingthefollowingXMLrequesttotheURL:http://localhost:8912.

<?xmlversion="1.0"encoding="UTF-8"?>

<env:Envelope

xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:tns="http://servicemix.apache.org/samples/wsdl-

xmlns:tns="http://servicemix.apache.org/samples/wsdl-

first/types">

<env:Body>

<ServiceParamTO>

<customerTO>

<firstName>Ann</firstName>

<lastName>Binil</lastName>

<addressTO>

<houseNumber>222</houseNumber>

<street>LakeView</street>

<city>Cochin</city>

</addressTO>

</customerTO>

<creditCardTO>

<cardNumber>8888-9999-1111-2222</cardNumber>

<validTill>01-APR-2007</validTill>

<cardType>MasterCard</cardType>

</creditCardTO>

</ServiceParamTO>

</env:Body>

</env:Envelope>

UnmarshallingtoTransferObjectsWehaveasetofJavaTOclassessothattheXStreamcanunmarshaltheaboveXMLdocumenttotheTOinstancesandbacktotheXMLwheneverrequired.Thisisshowninthefollowinglist:

ch12\JavaXmlBinding\src\com\binildas\esb\javasource\ServiceParamTO.java

publicclassServiceParamTOimplements

Serializable

{

privateCustomerTOcustomerTO;

privateCreditCardTOcreditCardTO;

}

ch12\JavaXmlBinding\src\com\binildas\esb\javasource\CustomerTO.java

publicclassCustomerTOimplements

Serializable

{

privateStringfirstName;

privateStringlastName;

privateAddressTOaddressTO;

}

ch12\JavaXmlBinding\src\com\binildas\esb\javasource\AddressTO.java

publicclassAddressTOimplements

Serializable{

privateStringhouseNumber;

privateStringstreet;

privateStringcity;

}

ch12\JavaXmlBinding\src\com\binildas\esb\javasource\CreditCardTO.java

publicclassCreditCardTOimplements

Serializable{

privateStringcardNumber;

privateStringvalidTill;

privateStringcardType;

}

TheseclassesarerelatedasshowninthefollowingUMLclassdiagram:

HttpInterceptorComponentTheHttpInterceptorisaServiceMixTransformcomponent.Thiscomponentwillfirstinterceptthemessagecontents.TheXMLformattedmessagesentbytheHTTPclientwillbeinterceptedhere,andthenprintedouttotheconsole.WethenunmarshaltheXMLinstanceintoaJavainstanceusingXStream.TheJavainstanceisthensentthroughtheNMRtothenextcomponentintheflow,whichistheXStreamInspector.Letuslookintothecodeshownasfollows:

publicclassHttpInterceptorextends

TransformComponentSupport

{

protectedbooleantransform(MessageExchange

exchange,NormalizedMessagein,NormalizedMessage

out)throwsMessagingException

{

System.out.println("HttpInterceptor("+name+

").transform01.exchange.getService()="+

exchange.getService());

XStreamxStream=null;

StringcontentString=null;

ServiceParamTOpayLoad=null;

ServiceParamTOpayLoad=null;

JavaSourcejavaSource=null;

QNameservice=null;

InOutinOut=null;

NormalizedMessagenormalizedMessageIn=null;

NormalizedMessagenormalizedMessageOut=null;

NormalizedMessagecopyReturnMessage=null;

SourcecontentReturn=null;

InputStreaminputStream=null;

byte[]bytes=null;

intavailable=0;

StringcontentReturnString=null;

NormalizedMessagecopyMessage=

exchange.createMessage();

getMessageTransformer().transform(exchange,in,

copyMessage);

Sourcecontent=copyMessage.getContent();

if(contentinstanceofDOMSource){

contentString=

XMLUtil.retreiveSoapContent(((DOMSource)

content).getNode());

System.out.println("HttpInterceptor("+name+

").transform02.contentString="+

contentString);

payLoad=(ServiceParamTO)

XStreamUtil.xmlToObject(contentString);

xStream=newXStream();

xStream.alias("ServiceParamTO",

ServiceParamTO.class);

xStream.alias("CustomerTO",CustomerTO.class);

xStream.alias("CreditCardTO",

CreditCardTO.class);

xStream.alias("AddressTO",AddressTO.class);

javaSource=newXStreamSource(payLoad,xStream);

service=newQName(namespaceURI,localPart);

inOut=createInOutExchange(service,null,null);

normalizedMessageIn=inOut.createMessage();

normalizedMessageIn.setContent(javaSource);

inOut.setInMessage(normalizedMessageIn);

sendSync(inOut);

normalizedMessageOut=inOut.getOutMessage();

copyReturnMessage=exchange.createMessage();

copyReturnMessage=exchange.createMessage();

getMessageTransformer().transform(exchange,

normalizedMessageOut,copyReturnMessage);

contentReturn=copyReturnMessage.getContent();

if(contentReturninstanceofStringSource)

{

try

{

inputStream=((StringSource)contentReturn).

getInputStream();

available=inputStream.available();

bytes=newbyte[available];

inputStream.read(bytes);

}

catch(IOExceptionioException)

{

thrownewMessagingException(ioException);

}

contentReturnString=newString(bytes);

System.out.println("HttpInterceptor("+name+

").transform03.contentReturnString="+

contentReturnString);

out.setContent(contentReturn);

System.out.println("HttpInterceptor("+name+

").transform04.contentReturnString="+

contentReturnString);

}

System.out.println("HttpInterceptor("+name+

").transform05.End");

}

returntrue;

}

}

Inthecode,wecreateaninstanceofXStreamandregisterallTOclassestoXStream.ThenusingthisXStreaminstanceandtheXMLpayload,wecreateaninstanceofXStreamSource.TheXStreamSourceinstanceisa

JavaSourcetype,whichagainisajavax.xml.transform.Sourcetype.ThismakesiteasyforustosetthisJavaSourceintotheInOutofthemessageexchangeinthenextchainoftheinteraction,tobesenttothedestinationservicewhichisXStreamInspector.

XStreamInspectorComponentComparedtoHttpInterceptor,theXStreamInspectorclassissimple.Itretrievesbackthemessagecontentandprintsittotheconsole.TheXStreamInspectorclassthensendsthesameXMLcontentbacktoHttpInspector.

publicclassXStreamInspectorextends

TransformComponentSupport

{

protectedbooleantransform(MessageExchange

exchange,NormalizedMessagein,NormalizedMessage

out)throwsMessagingException

{

System.out.println("XStreamInspector("+name+

").transform01.exchange.getService()="+

exchange.getService());

NormalizedMessagecopyMessage=

exchange.createMessage();

getMessageTransformer().transform(exchange,in,

copyMessage);

Sourcecontent=copyMessage.getContent();

StringcontentString=null;

if(contentinstanceofDOMSource)

{

contentString=

XMLUtil.node2XML(((DOMSource)content).

XMLUtil.node2XML(((DOMSource)content).

getNode());

System.out.println("XStreamInspector("+name+

").transform02.contentString="+

contentString);

}

out.setContent(newStringSource(contentString));

System.out.println("XStreamInspector("+name+

").transform03.End");

returntrue;

}

}

ConfigureInterceptorandInspectorComponentsWecanconfiguretheHttpInterceptorandXStreamInspectorcomponentsinasingleSU.Hence,wewilldotheconfigurationofthesecomponentsasanSUintheservicemix.xmlfilekeptatch12\JavaXmlBinding\su\servicemix.xml.

Thecontentsofthisfileisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:demo="http://www.binildas.com/esb/LightWeightOrPojo">

<classpath>

<location>.</location>

</classpath>

<sm:serviceunitid="jbi">

<sm:activationSpecs>

<sm:activationSpeccomponentName="interceptor"

endpoint="interceptor"

service="demo:interceptor">

<sm:component>

<beanclass="com.binildas.esb.

javasource.HttpInterceptor">

<propertyname="name">

<value>Interceptor-1</value>

</property>

<propertyname="namespaceURI">

<value>

http://www.binildas.com/esb/LightWeightOrPojo

</value>

</property>

<propertyname="localPart">

<value>inspector</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="inspector"

endpoint="inspector"service="demo:inspector">

<sm:component>

<beanclass="com.binildas.esb.javasource.

XStreamInspector">

<propertyname="name">

<value>Inspector-1</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:serviceunit>

</beans>

PackageInterceptorandInspector

ComponentsWewillcreateanSUandthenpackageitintoanSA.WehavealreadyseentheSUconfiguration,letusnowlookintotheSAconfigurationat:

ch12\JavaXmlBinding\sa\META-INF\jbi.xml

Thejbi.xmlfileisreproducedinthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<jbixmlns="http://java.sun.com/xml/ns/jbi"

version="1.0">

<service-assembly>

<identification>

<name>InterceptorAssembly</name>

<description>InterceptorService

Assembly</description>

</identification>

<serviceunit>

<identification>

<name>Interceptor</name>

<description>InterceptorService

Unit</description>

</identification>

<target>

<artifacts-zip>Interceptor-su.zip</artifacts-zip>

<component-name>servicemix-

lwcontainer</component-name>

</target>

</serviceunit>

</service-assembly>

</jbi>

DeployInterceptorandInspectorComponentsThemainpointtobenotedintheSAjbi.xmlisthetargetelementoftheserviceunit.HerewespecifythattheSUartifact(thatisInterceptor-su.zip)istobedeployedintotheservicemix-lwcontainertargetcontainer.

Todothis,wehaveservicemix.xmlfileinthetopmostfoldertostarttheServiceMixcontainer.Thisisshownasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:demo="http://www.binildas.com/esb/LightWeightOrPojo">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<sm:containerid="jbi"rootDir="./wdir"

installationDirPath="./install"

deploymentDirPath="./deploy"flowName="seda"

monitorInstallationDirectory="true"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpeccomponentName="httpReceiver"

service="bt:httpBinding"endpoint="httpReceiver"

destinationService="demo:interceptor">

<sm:component>

<bean

class="org.apache.servicemix.components.http.

HttpConnector">

<propertyname="host"value="127.0.0.1"/>

<propertyname="port"value="8912">

<bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

HereyoucanseethatweconfigureanHttpConnectortolistenatport8912.ItistothistargetthattheHTTPClientsendstheXMLrequest.

BuildandRuntheSampleAsafirststep,ifyouhaven'tdoneitbefore,editexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter),andchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Tobuildandrunthesample,firstchangedirectorytoch12\JavaXmlBindingfolderandexecuteantasshownhere:

cdch12\JavaXmlBinding

ant

WecanbringupServiceMixbyrunningthefollowingcommands:

cdch12\JavaXmlBinding

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

WhenwestartServiceMix,theJBIcontainerisconfiguredusingtheaboveservicemix.xmlfile.

Torunthedemo,thereisaClient.htmlfileprovidedinthetop-levelfolder.

SummaryYouhavealreadydeployedPOJOcomponentsintoServiceMixandexposedthemasservices.AnexternalclientcaninvokethePOJOservicesbysendingSOAPrequestsandreceivingbacktheSOAPresponses.Attimes,youmayalsoneedtodealwithnon-SOAPformatted,butplainXMLmessages.Wealsoneedtostreamsuchmessagestoothroughfirewallstothebusandgetthemprocessed.

ThischaptershowedyouhowwecandothisusingXStream.Somelegacyintegrationscenariomightwarrantthisapproach.YoumightalsohavenotedthefactthatwecanreplacetheXStreamusedinthissamplewithanyotherJavaXMLbindingframeworksuchasCastororXMLBeans,butXStream'sadvantageisthebuilt-inintegrationXStreamhas

withtheServiceMixJBI.

TheServiceMixJBIbusprovidesaframeworkformanylightweightintegrationlibrarieslikeXStream.ItalsorealizesmanydesignpatternsusedinsoftwareengineeringlikethewellknownProxypatternwhichwewillexploreinthenextchapter.

Chapter13.JBIProxyOneofthemostusefulclassesintroducedbyJDK1.3istheProxyclassinthejava.lang.reflectpackage.Itallowsustocreateclassesimplementingaparticulartype(interface)onthefly.ServiceMixprovidesasimilarAPIinJBIsothatwecanproxyaparticularserviceintheJBIbus.Thishelpsustoimplementmanyfunctionalitiessuchas:

Interceptingandre-routingtheservices.

Wrappingandunwrappingmessagestargetedtoaservice.

Usingrequest-message,formattedforaparticularservicetype,foradifferentservicetype.

Inthischapter,wewillfirstrevisitJDKProxyclasses.ThiswillsetabackgroundforfurtherreadingwhereinwewillexplainJBIProxyindetailwithexamplesformultiplescenarios.ThenthedeveloperwillbeabletomakeuseofProxypatternwithintheJBI-basedESB,tosuittheirtechnicalrequirements.

Wewillcoverthefollowinginthischapter:

Proxydesignpatterningeneral

ProxysupportinJavaSDKwithexamples

ServiceMixJBIProxy

AfewsamplesofdefiningandexposingproxiestoservicesintheJBIbus

ApracticaluseofJBIProxy—toproxyexternalwebservicesintheJBIbus

Proxy—APrimerWikipediadefinesProxyas:

Proxymayrefertosomethingwhichactsonbehalfofsomethingelse.

Inthesoftwareaproxyisasubstituteforatargetinstanceandisageneralpatternwhichappearsinmanyotherpatternsindifferentvariants.

ProxyDesignPatternAproxyisasurrogateclassforthetargetobject.Ifamethodcallhastobeinvokedinthetargetobject,ithappensindirectlythroughtheproxyobject.Thefeaturewhichmakesproxyidealformanysituationsisthattheclientorthecallerisnotawarethatitisdealingwiththeproxyobject.Theproxyclassisshowninthefollowingfigure:

Intheabovefigure,whenaclientinvokesamethodtargettowardstheTargetservice,theproxyinterceptsthecallinbetween.Theproxyalsoexposeasimilarinterfacetothetarget,hencetheclientisunawareofthedealingwiththeproxy.Thustheproxymethodisinvoked.Theproxythendelegatesthecalltotheactualtargetsinceitcannotprovide

theactualfunctionality.Whendoingso,theproxycanprovidecallmanagementtowardstheactualmethod.Theentiredynamicsisshowninthefollowingfigure:

Aproxyisusuallyimplementedbyusingacommon,sharedinterfaceorsuperclass.Boththeproxyandthetargetsharethiscommoninterface.Then,theproxydelegatesthecallstothetargetclass.

JDKProxyClassJDKprovidesboththeclassProxyandtheinterfaceInvocationHandlerinthejava.lang.reflectpackage,sinceversion1.3.UsingJDKProxyclasses,youcancreateyourownclassesimplementingmultipleinterfacesofyourchoice,atruntime.

Proxyisthesuperclassforanydynamicproxyinstancesyoucreateatruntime.Moreover,theProxyclassalsoaccommodatesahostofstaticmethodswhichwillhelpyoutocreateyourproxyinstances.getProxyClassandnewProxyInstancearetwosuchutilitymethods.

TheProxyAPIislistedinthefollowinginbrevity:

packagejava.lang.reflect;

publicclassProxyimplements

java.io.Serializable

{

protectedInvocationHandlerh;

protectedProxy(InvocationHandlerh);

publicstaticInvocationHandler

getInvocationHandler(Objectproxy)throws

IllegalArgumentException;

publicstaticClass<?>getProxyClass(ClassLoader

loader,Class<?>...interfaces)throws

IllegalArgumentException;

publicstaticbooleanisProxyClass(Class<?>cl);

publicstaticObjectnewProxyInstance(ClassLoader

loader,Class<?>[]interfaces,InvocationHandler

h)throwsIllegalArgumentException

}

Intheabovecode,youcaninvoketheProxy.getProxyClasswithaclassloaderandanarrayofinterfacesforwhichyouneedtoproxy,togetaClassinstancefortheproxy.Proxyobjectshaveoneconstructor,towhichyoupassanInvocationHandlerobjectassociatedwiththatproxy.Whenyouinvokeamethodontheproxyinstance,themethodinvocationisencodedanddispatchedtotheinvokemethodofitsinvocationhandler.LetusalsolookattheInvocationHandlerAPIreproducedasfollows:

packagejava.lang.reflect;

publicinterfaceInvocationHandler

{

Objectinvoke(Objectproxy,Methodmethod,

Object[]args)throwsThrowable;

}

Weneedtoimplementthisinterfaceandprovidecodefortheinvokemethod.OnceyougetaClassinstancefortheproxybyinvokingtheProxy.getProxyClasswithaclassloaderandanarrayofinterfacesforwhichyouneedtoproxyto.Now,youcangetaConstructorobjectforthisproxyfromtheClassinstance.OntheconstructoryoucanusenewInstance(passinginaninvocationhandlerinstance)tocreatetheproxyinstance.ThecreatedinstanceshouldbeimplementingalltheinterfacesthatwerepassedtogetProxyClass.Thestepsareshowninthefollowingcode:

InvocationHandlerhandler=new

SomeInvocationHandler(...);

ClassproxyClazz=

Proxy.getProxyClass(Blah.class.getClassLoader(),

newClass[]{Blah.class});

Blahblah=(Blah)proxyClazz.getConstructor(new

Class[]{InvocationHandler.class

}).newInstance(newObject[]{handler});

Thereisalsoashortcuttogetaproxyobject.YoucaninvokeProxy.newProxyInstance,whichtakesaclassloader,anarrayofinterfaceclasses,andaninvocationhandlerinstance.

InvocationHandlerhandler=new

SomeInvocationHandler(...);

Blahblah=(Blah)

Proxy.newProxyInstance(Blah.class.

getClassLoader(),newClass[]{Blah.class},

getClassLoader(),newClass[]{Blah.class},

handler);

Nowyoucaninvokemethodsontheproxyobjectduringwhichthesemethodinvocationsareturnedintocallsontotheinvocationhandler'sinvokemethodisshownhere:

blah.interfaceMethod();

SampleJDKProxyClassWewillnowwritesomesimplecodetodemonstratehowyoucanwriteyourownproxiesatruntime,foryourinterfaceclasses.

Asafirststep,ifyouhaven'tdoneitbefore,editexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter),andchangethepathstheretomatchyourdevelopmentenvironment.ThecodedownloadforthischapteralsoincludesaREADME.txtfile,whichgivesdetailedstepstobuildandrunthesamples.

Wewillnowlookatthesourcecodethatcanbefoundinthefolderch13\JdkProxy\src.

Thefilesareexplainedhere:

ch13\JdkProxy\src\SimpleIntf.java

publicinterfaceSimpleIntf

{

publicvoidprint();

}

}

SimpleIntfisasimpleinterfacewithasinglemethodprint.printdoesnotacceptanyparametersandalsodoesnotreturnanyvalue.OuraimisthatwhenweinvokemethodsontheproxyobjectforSimpleIntf,themethodinvocationshouldbeturnedintocallstoaninvocationhandler'sinvokemethod.Letusnowdefineaninvocationhandlerinthefollowingcode:

ch13\JdkProxy\src\SimpleInvocationHandler.java

importjava.lang.reflect.InvocationHandler;

importjava.io.Serializable;

importjava.lang.reflect.Method;

publicclassSimpleInvocationHandlerimplements

InvocationHandler,Serializable

{

publicSimpleInvocationHandler(){}

publicObjectinvoke(finalObjectobj,Method

method,Object[]args)throwsThrowable

{

if(method.getName().equals("print")&&(args==

null||args.length==0))

{

System.out.println("SimpleInvocationHandler.invoked");

}

else

{

thrownewIllegalArgumentException("Interface

methoddoesnotsupportparam(s):"+args);

}

returnnull;

}

}

SinceSimpleIntf.print()doesnotacceptanyparametersandalsodoesnotreturnanyvalue,intheinvokemethodofSimpleInvocationHandler,wedoublechecktheintentionbehindtheactualinvoker.Inotherwords,wecheckthatnoparametersarepassedandwereturnnullonly.

Now,wehaveallthenecessaryclassestoimplementaproxyforSimpleIntfinterface.LetusnowexecuteitbywritingaTestclass.

ch13\JdkProxy\src\Test.java

importjava.lang.reflect.Proxy;

importjava.lang.reflect.InvocationHandler;

publicclassTest

{

publicstaticvoidmain(String[]args)

{

InvocationHandlerhandler=new

SimpleInvocationHandler();

SimpleIntfsimpleIntf=

(SimpleIntf)Proxy.newProxyInstance

(SimpleIntf.class.getClassLoader(),newClass[]{

SimpleIntf.class},handler);

simpleIntf.print();

}

}

ThewiringoftheabovedescribedinterfacesandclassesarebetterrepresentedintheUMLclassdiagraminthefollowingfigure:

Theabovefigureshowstherelationshipbetweenvariousclassesandinterfacesinthesample.$Proxy0classrepresentstheactualproxyclassgeneratedontheflyandasyoucandeduceitfromtheclassdiagram.$Proxy0isatypeofourinterface(SimpleIntf).

Tobuildthesample,firstchangedirectorytoch13\JdkProxyandexecuteantasshownhere:

cdch13\JdkProxy

ant

ThecommandantrunwillexecutetheTestclasswhichwillprintoutthefollowingintheconsole:

ServiceMixJBIProxyJavaproxiesfortheJBIendpointscanbecreatedinServiceMixusingJSR181components.Forthis,therequirementisthattheJBIendpointsshouldexposeaWSDL.

Ajsr181:endpointtakesavaluefortheserviceInterfaceattribute.TheJBIcontainerwillbeabletogeneratetheWSDLoutofthisserviceInterface.Thus,ifwehaveajsr181:endpointexposingservicetotheJBIbus,itispossibletoprovideaproxyforthatservicetoo.

ThebasicconfigurationfordefiningaJBIproxyisshownasfollows:

<jsr181:proxyid="proxyBean"container="#jbi"

interfaceName="test:HelloPortType"

type="test.Hello"/>

Onceaproxyisdefined,thesamecanthenbereferencedfromyourclientbeanorfromoneofyourcomponents.Theproxied

JBIendpointcanthenbeinvokedjustlikeanormalPOJO.

IfyouwanttodefineaJBIproxywithinaSU,youcanfollowtheconfigurationgivenasfollows:

<jsr181:endpointannotations="none"

service="test:echoService"

serviceInterface="test.Echo">

<jsr181:pojo>

<beanclass="test.EchoProxy">

<propertyname="echo">

<jsr181:proxyservice="test:EchoService"

context="#context"type="test.IService">

<property>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

Letusnowlookintoafewexamplestomaketheconceptclearer.

JBIProxySampleImplementingCompatibleInterfaceFirst,wewillcreateaJBIproxyimplementinganinterfacecompatiblewiththetargetservice.Then,inplaceofthetargetservicewewillusetheproxyinstance,sothatanycallsintendedforthetargetservicewillbefirstroutedtotheproxy.Theproxyinturnwilldelegatethecalltothetargetservice.

Thestructuralrelationshipbetweenvariousclassesparticipatingintheinteractionisshowninthefollowingfigure:

Here,EchoProxyServiceistheclasswhichwelaterexposeintheJBIbusastheservice.ThisclassimplementstheIEchointerface.Inordertodemonstratetheproxy,EchoProxyServicedoesn'timplementtheserviceassuch,insteaddependsontheJbiProxyderivedoutofanotherclassTargetService.TheTargetServicecontainstheactualservicecode.Asyoucansee,boththeEchoProxyServiceandtheTargetServiceimplementthesameinterface.

ProxyCodeListingThecodebaseforthesampleislocatedinthefolderch13\JbiProxy\

01_CompatibleInterface\01_JsrProxy\src.

ThisfoldercontainsaninterfaceIEchoandtwootherclassesimplementingtheIEchointerfacenamely

EchoProxyServiceandTargetService.Theseclassesareexplainedhere:

IEcho.java:TheIEchointerfacedeclaresasinglemethodechowhichtakesaStringparameterandreturnsaString.

publicinterfaceIEcho

{

publicStringecho(Stringinput);

}

EchoProxyService.java:EchoProxyServiceisaconvenientclasswhichwillactasmechanismforroutingrequeststotheJBIproxy.Moreover,EchoProxyServiceimplementstheaboveinterfaceIEcho.

publicclassEchoProxyServiceimplements

IEcho

{

privateIEchoecho;

publicvoidsetEcho(IEchoecho)

{

this.echo=echo;

}

publicStringecho(Stringinput)

{

System.out.println("EchoProxyService.echo.

this="+this);

returnecho.echo(input);

}

}

TargetService.java:TargetServicealsoimplementstheinterfaceIEcho.TargetServiceissupposedtobeourtargetservice,andwewillbegeneratingaJBIproxyfortheTargetService.

publicclassTargetServiceimplementsIEcho

{

publicStringecho(Stringinput)

{

System.out.println("TargetService.echo:

System.out.println("TargetService.echo:

String.this="+this);

returninput;

}

}

XBean-basedJBIProxyBindingUsingXBean,wewillnowconfiguretheJBIproxytobedeployedontothestandardservicemix-jsr181JBIcomponent.Thexbean.xmlisasshownasfollows:

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:test="http://test">

<classpath>

<location>.</location>

</classpath>

<jsr181:endpointannotations="none"

service="test:echoService"

serviceInterface="test.IEcho">

<jsr181:pojo>

<beanclass="test.EchoProxyService">

<propertyname="echo">

<jsr181:proxyservice="test:TargetService"

context="#context"type="test.IEcho">

<property>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

<jsr181:endpointannotations="none"

service="test:TargetService"

serviceInterface="test.IEcho">

<jsr181:pojo>

<beanclass="test.TargetService">

<jsr181:pojo>

</jsr181:endpoint>

</beans>

HerewefirstwirebothEchoProxyServiceandTargetServiceasJSR181-compliantservicesontotheJBIbus.NextwedefineaJBIproxyfortheTargetService.Ifwecloselyobservetheproxyconfiguration,wecanseethatweareinsistingthattheproxytoimplementthetypetest.IEcho.Thatmakessenseandisnotasurprisesincethetargetserviceclass,test:TargetServiceisalsooftypetest.IEcho.

DeploymentConfigurationFordeployment,wewillpackagetherelevantartifactsfortheJSRproxybindingintoastandardSA.WewillalsohaveanHTTPboundSAsothatwecanuseasimpleHTTPclienttotestthesetup.Astheconfigurationsareexactlythesameaswhatweusedinthepreviousexample,theyarenotrepeatedhere.

DeployingandRunningtheSampleTobuildtheentirecodebaseanddeploythesample,changedirectorytoch13\JbiProxy\01_CompatibleInterfacewhich

containsatop-levelbuild.xmlfile.Executeantasshownhere:

cdch13\JbiProxy\01_CompatibleInterface

ant

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder.

cdch13\JbiProxy\01_CompatibleInterface

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

TheClient.htmlprovidedagaininthesamefoldercanbeusedtosendmessagestotestthedeployedservice.NowclickingSendontheclientwillroutetherequestmessagetotheServiceMixESB.AttheServiceMixconsole,youcanseethatEchoProxyService.echoisinvokedfirst,whichwillthendelegatethecalltoTargetService.echo.Thisisshowninthefollowingscreenshot:

JBIProxySampleimplementingInCompatibleinterfaceInthesecondsampleonJBIProxy,wewillmakeasimplebutsignificantchangeintheinterfacesimplemented.WewillcreateaJBIproxyimplementinganinterfaceincompatibletothetargetservice.Then,inplaceofthetargetservicewewillusetheproxyinstance.Thenanycallsintendedtothetargetservicewillbefirstroutedtotheproxyandtheproxyinturnwilldelegatethecalltothetargetservice.Thestructuralrelationshipbetweenvariousclassesparticipatingintheinteractionisshowninthefigure:

Intheabovefigure,youmighthavenoticedthateventhoughweusetwocompletelydifferenttypes(IEchoandITarget)astheinterfaces,themethodsdeclaredinthesetwointerfacesarethesameineveryrespect.Thisisahackwewanttointroduceintentionally.InotherwordsouraimhereistoinvokethemethodinTargetService.But,wewanttodoitthroughtheproxyonly.Wewanttheproxytobecreated

implementingadifferentinterface,IEcho.Hence,IEchoisdifferentfromtheITarget.ThismeansifwegobythenormalJavatypecompatibilityrules,theproxywhichwecreatedhereis"technicallyincompatible"withthetargetservice.Butaproxyisaproxyandhenceitcanproxycallseventoadifferenttype.However,Aswewanttoinvokethesamemethodintheproxytoo,wehavepurposefullykeptthemethodnamesameinboththeproxyinterfaceandthetargetserviceinterface.

ProxyCodeListingThecodebaseforthesampleislocatedinthefolderch13\JbiProxy\02_IncompatibleInterface\01_

JsrProxy\src.

ThisfoldercontainstheinterfaceIEchoandtheclassEchoProxyServiceimplementingtheIEchointerface.Now,wehaveonemoreinterfaceITargetandanotherclassTargetServiceimplementingtheITargetinterface.

Theseclassesareexplainedhere:

IEcho.java:Inthissamplealso,theIEchointerfacedeclaresasinglemethodechowhichtakesaStringparameterandreturnsaStringtoo.

publicinterfaceIEcho

{

publicStringecho(Stringinput);

}

EchoProxyService.java:HerealsotheEchoProxyServiceisa

convenientclasswhichwillactasmechanismforroutingrequeststotheJBIProxy.Moreover,EchoProxyServiceimplementstheaboveinterfaceIEcho.

publicclassEchoProxyServiceimplements

IEcho

{

privateIEchoecho;

publicvoidsetEcho(IEchoecho)

{

this.echo=echo;

}

publicStringecho(Stringinput)

{

System.out.println("EchoProxyService.echo.

this="+this);

returnecho.echo(input);

}

}

ITarget.java:Here,weintroduceanewinterfaceITarget,whichisincompatibletotheinterfaceIEcho.Butpurposefullywehaveretainedthemethodecho.

publicinterfaceITarget

{

Stringecho(Stringinput);

}

TargetService.java:Asperourdiscussionearlier,TargetServiceimplementsthenewinterfaceITarget,notIEcho.

publicclassTargetServiceimplementsITarget

{

publicStringecho(Stringinput)

{

System.out.println("TargetService.echo:

String.this="+this);

returninput;

}

}

XBean-basedJBIProxyBindingUsingXBean,wewillnowconfiguretheJBIproxytobedeployedontothestandardservicemix-jsr181JBIcomponent.Thexbean.xmlisasshownasfollows:

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:test="http://test">

<classpath>

<location>.</location>

</classpath>

<jsr181:endpointannotations="none"

service="test:echoService"

serviceInterface="test.IEcho">

<jsr181:pojo>

<beanclass="test.EchoProxyService">

<propertyname="echo">

<jsr181:proxyservice="test:TargetService"

context="#context"type="test.IEcho">

<property>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

<jsr181:endpointannotations="none"

service="test:TargetService"

serviceInterface="test.ITarget">

<jsr181:pojo>

<beanclass="test.TargetService">

<jsr181:pojo>

</jsr181:endpoint>

</beans>

Observetheproxyconfigurationagain.Wecanseethatthistimeweareinsistingthattheproxyimplementsthetypetest.IEcho,eventhoughtheinterfacetypeforthetargetserviceistest.ITarget.Thisiswhataproxyisallabout.Inclearterms,theJBIherewillgenerateaproxyfortest.TargetService.Sotheproxy'sexposedinterfaceis,bydefault,complianttotest.ITarget.However,wewanttheproxytobecomplianttotest.IEchoalso,whichistheinterfacetheclientinitiallytargetedto.

DeploymentConfigurationFordeployment,wewillpackageagainalltherelevantartifactsfortheJSRproxybindingintoastandardSA.WewillalsohaveanHTTPboundSAsothatwecanuseasimpleHTTPclienttotestthesetup.Astheconfigurationsareexactlythesameaswhatweusedinpreviousexample,theyarenotrepeatedhere.

DeployingandRunningtheSampleTobuildtheentirecodebaseanddeploythesample,changedirectorytoch13\JbiProxy\02_IncompatibleInterface

whichcontainsatop-levelbuild.xmlfile.Executeantasshownhere:

cdch13\JbiProxy\02_IncompatibleInterface

ant

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder.

cdch13\JbiProxy\02_IncompatibleInterface

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

TheClient.htmlfileprovidedinthesamefoldercanbeusedtosendmessagestotestthedeployedservice.NowclickingSendontheclientwillroutetherequestmessagetotheServiceMixESB.AttheServiceMixconsoleyoucanseethatEchoProxyService.echoisinvokedfirstwhichwillthendelegatethecalltoTargetService.echo.Thisisshowninthefollowingscreenshot:

InvokeExternalWebServicefromtheServiceMixSampleYouhavenowseenhowtosetupaJBIproxyandhowtoinvokeaproxyjustlikeaPOJOboundtoJBI.NowyoucanextendthesameprinciplesifyouneedtocalloutfromaJSR181SUtoaHTTPproviderinordertointeractwithanexternalwebservice.YoucanuseXFiretocreatestubclassesbasedonyourWSDLexposedbyyourexternalwebservice.NowyoucaninjectthestubintoyourJSR181SU.ThestubwillbeusedbytheproxytogeneratetheexchangewiththeHTTPprovider(whichshouldbereferencedasthe"service").

YouhavealreadyseeninChapter10,howtobindawebserviceexternaltotheJBIontotheJBIbus.ThenanyJBIcomponentcanexchangemessageswiththeremotewebservice.Oneaspectwhichyouneedtonoteisthatwehavebeenexchangingmessagesinadocument-orientedfashion.HoweverusingJBIproxynow,itispossibletoinvokewebservicesintheRPCstylefromwithintheJBIbus.ForthisweleveragethestubclassesgeneratedoutfromthewebserviceWSDLusingAxis.

WebServiceCodeListingWeareinterestedinproxysetuptoaccessaremotewebservice,hencewewillnotdiscussthedetailsofthewebservicedeploymentinthissection.Instead,wewilljustbrowsethroughtheimportantwebserviceinterfacesandthe

associatedWSDLandthenmoveontobindingtheproxy.

ThewebserviceimplementstheIHelloWebremoteinterfacewhichinturnextendstheIHellobusinessinterface.Theyarelistedhereasfollows:

IHello.java:IHelloisasimpleBI,havingasinglebusinessmethodhello.

publicinterfaceIHello

{

Stringhello(Stringparam);

}

IHelloWeb.java:Inordertodeployawebservice,weneedaninterfacecomplyingwiththeJavaRMIsemantics,andIHelloWebwillservethispurpose.

publicinterfaceIHelloWebextendsIHello,

java.rmi.Remote{}

HelloWebService.wsdl:

ThemainsectionsinthewebserviceWSDLisshownasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

targetNamespace="http://AxisEndToEnd.

axis.apache.binildas.com"...>

<wsdl:types...>

<wsdl:message...>

<wsdl:portTypename="IHelloWeb">

</wsdl:portType>

<wsdl:binding

name="HelloWebServiceSoapBinding"

type="impl:IHelloWeb">

</wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebServiceSoapBinding"

name="HelloWebService">

<wsdlsoap:address

location="http://localhost:8080/AxisEndToEnd/services/

HelloWebService">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

Thisisenoughaboutthewebserviceandwewillmoveontothenextstep.

AxisGeneratedClientStubsWeuseorg.apache.axis.wsdl.WSDL2Javaclassinthewsdl2javatasktogenerateclient-sidebindingclassesandstubs.Themainclassesareavailableinthefolderch13\JbiProxy\03_AccessExternalWebService\

01_ws\gensrcandtheyareasfollows:

HelloWebService.java

HelloWebServiceSoapBindingStub.java

IHelloWeb.java

IHelloWebService.java

IHelloWebServiceLocator.java

AlltheaboveartifactsareAxisgeneratedclient-sidestubs,hencewewillnotlookintothedetailsofthemhere.Instead,letuslookintothestructuralrelationshipbetweenthevariousdevelopercreatedandAxisgeneratedartifactsshowninthe

followingfigure:

Referringtotheabovediagram,letusunderstandtherelevantartifacts.Similartothesamplespreviouslylistedinthischapter,hereouraimistogenerateaJBIproxyforan

externallyboundwebservice.Wearedoingthisusingthefollowingclasses:

ITarget.java:ThisinterfaceissynonymoustotheBIIHello,havingasinglebusinessmethodhello.Wewanttoauto-routerequest-responsethroughtheJBIproxy.Inordertofacilitatethiswehaveretainedthemethodsignatureintheinterfacesthesame.

publicinterfaceITarget

{

Stringhello(Stringinput);

}

TargetService.java:InTargetService,weauto-wirethewebservicestub.So,thehelloWebinstancefieldinTargetServicewillholdareferencetothestubtothewebservice.WhenthehellomethodisinvokedinTargetService,thecallisdelegatedtothestubwhichwillinvoketheremotewebservice.

publicclassTargetServiceimplementsITarget

{

private

com.binildas.apache.axis.AxisEndToEnd.

IHelloWebhelloWeb;

publicTargetService(){}

public

TargetService(com.binildas.apache.axis.

AxisEndToEnd.IHelloWebhelloWeb)

{

this.helloWeb=helloWeb;

}

publicStringhello(Stringinput)

{

System.out.println("TargetService.echo:

String.this="+this);

try

{

returnhelloWeb.hello(input);

}

catch(Exceptionexception)

catch(Exceptionexception)

{

exception.printStackTrace();

returnexception.getMessage();

}

}

}

IHelloProxy.java:WenowneedtowiretheJBIproxytothewebservicesstub.IHelloProxyisaninterfacedefinedforthispurposeandhenceishavingthesamesinglebusinessmethod,hello.

publicinterfaceIHelloProxy

{

publicStringhello(Stringinput);

}

IHelloProxyService.java:HelloProxyServiceisawrapperoradapterfortheJBIproxy.Inotherwords,thehelloProxyinstancefieldinHelloProxyServicewillrefertotheJBIproxy.

publicclassHelloProxyServiceimplements

IHelloProxy

{

privateIHelloProxyhelloProxy;

publicvoidsetHelloProxy(IHelloProxy

helloProxy)

{

this.helloProxy=helloProxy;

}

publicStringhello(Stringinput)

{

System.out.println("HelloProxyService.hello.

this="+this);

returnhelloProxy.hello(input);

}

}

ThebeanwiringdiscussedinthissectionisdoneusingSpringandisshowninthenextsection.

XBean-basedJBIProxyBindingUsingXBean,wewillnowconfiguretheJBIproxytobedeployedontothestandardservicemix-jsr181JBIcomponent.

Thexbean.xmlisasshowninthefollowingcode:

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:jsr181="http://servicemix.apache.org/jsr181/1.0"

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:test="http://test">

<classpath>

<location>.</location>

</classpath>

<jsr181:endpointannotations="none"

service="test:echoService"

serviceInterface="test.IHelloProxy">

<jsr181:pojo>

<beanclass="test.HelloProxyService">

<propertyname="helloProxy">

<jsr181:proxyservice="test:TargetService"

context="#context"type="test.IHelloProxy">

<property>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

<jsr181:endpointannotations="none"

service="test:TargetService"

serviceInterface="test.ITarget">

<jsr181:pojo>

<beanclass="test.TargetService">

<constructor-argtype="com.binildas.apache.axis.

AxisEndToEnd.IHelloWeb">

<refbean="stub">

<constructor-arg>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

<beanid="stub"

class="com.binildas.apache.axis.AxisEndToEnd.

HelloWebServiceSoapBindingStub">

<constructor-argtype="java.net.URL"index="0">

<refbean="url">

<constructor-arg>

<constructor-argtype="javax.xml.rpc.Service"

index="1">

<refbean="serviceLocator">

<constructor-arg>

</bean>

<beanid="url"class="java.net.URL">

<constructor-arg>

<value>http://localhost:8080/AxisEndToEnd/

services/HelloWebService</value>

</constructor-arg>

</bean>

<beanid="serviceLocator"

class="com.binildas.apache.axis.AxisEndToEnd.

IHelloWebServiceLocator">

</bean>

</beans>

Wenowhaveenoughconfigurationstoinvoketheexternalwebservice.Isthereanythingfishyintheconfigurationabove?YoucangothroughthatonceagainandletmewaittilltheendofourdiscussiontoexplainwhatIamhidingfromyouatthispoint.

DeploymentConfigurationFordeployment,wewillpackageagainalltherelevantartifactsfortheJSRproxybindingintoastandardSA.WewillalsohaveanHTTPboundSAsothatwecanuseasimpleHTTPclienttotestthesetup.Astheconfigurationsareexactlythesameaswhatweusedinthepreviousexample,theyarenotrepeatedhere.Butweneedtomentiononethinghere.TheJBIproxyuseswebservicestubclassestoinvoketheexternalserviceandhencedependsontheAxislibraries.WeresolvethisdependencybycompilingthestubclassesandincludingthemalsointheSA.WealsocopyallrelevantAxisAPIjarstotheServiceMixoptionallibrarypath.Theanttargetforthatisgivenhere:

<targetname="copy-dependency"depends="init">

<javacsrcdir="../01_ws/gensrc"

destdir="${build.dir}">

<classpathrefid="javac.classpath"/>

<includename="**/*ServiceLocator.java">

<javac>

<copytodir="${servicemix.home}/lib/optional"

overwrite="true">

<filesetdir="${axis.home}/lib"includes="*.jar"

>

<copy>

</target>

DeployingandRunningtheSampleTobuildtheentirecodebaseanddeploythesample,changedirectoryto

ch13\JbiProxy\03_AccessExternalWebService

whichcontainsatop-levelbuild.xmlfile.Executeantasshownhere:

cdch13\JbiProxy\03_AccessExternalWebService

ant

Thiswillbuildthewebservice,generaterequiredwebserviceclientstubs,andalsopackageallthenecessaryserviceassemblies.First,weneedtodeploythewebservice.Forthat,transferthewebservicewarfileplacedinch13\JbiProxy\03_AccessExternalWebService\

01_ws\distfolderintothewebappsfolderofyourfavoritewebcontainerandrestartthecontainer.Youcandoublecheckwhetheryourwebservicedeploymentworksbyexecutingaclientkeptinthewebservicefolderitself.Forthat,executetheantruntargetasfollows:

ch13\JbiProxy\03_AccessExternalWebService\01_ws

antrun

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder.

ch13\JbiProxy\03_AccessExternalWebService

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

TheClient.htmlprovidedagaininthesamefoldercanbeusedtosendmessagestotestthedeployedservice.

ProxyandWSDLGenerationIhaveaskedyoutogothroughtheJBIproxyXBeanconfigurationoncemoreinaprevioussection.Doyouthinkwehaveactuallymadethewebserviceaproxy?Ifweneedtotrulyproxythewebservice,thentheXBeanconfigurationshouldbesomethinglikethefollowingcode:

<jsr181:endpointannotations="none"

service="test:TargetService"

serviceInterface="com.binildas.apache.axis.

AxisEndToEnd.IHelloWeb">

<jsr181:pojo>

<bean

class="com.binildas.apache.axis.AxisEndToEnd.

HelloWebServiceSoapBindingStub">

<constructor-argtype="java.net.URL"index="0">

<refbean="url">

<constructor-arg>

<constructor-argtype="javax.xml.rpc.Service"

index="1">

<refbean="serviceLocator">

<constructor-arg>

</bean>

</jsr181:pojo>

</jsr181:endpoint>

Theaboveconfigurationisrightandthatiswhatweneedtoproxythewebservice.HowevertheissuehereisthattheclassHelloWebServiceSoapBindingStub,whichifyoulookatthesourcecodeyoucansee,isdependentonmanyapacheaxisRPCAPIclasses.ForproperJBIproxying,theJBIcontainershouldbeabletogenerateWSDLoutoftheexposedAPIbutitmaynotmakesensetogenerateWSDLout

oftheseRPC-dependentclasses.InfacttheWSDLgeneratorfailsandthrowsanerror.HenceinsteadwhatwehavedoneinthepreviousexampleisthatwehaveaproxywrapperTargetServicetowhichweinjecttheHelloWebServiceSoapBindingStubinstanceusingtheSpringinjectionmechanism.ThenwedelegateanycallsfromtheTargetServiceinstancetothestubinstances,andthatdoesthemagic.

SummaryProxiesarestrongfeaturesintheJavalanguagepackage,andsimilarfunctionalitycanbeavailedfromwithinyourJBIESBusingJBIproxies.Interceptionandre-routingaresomeofthefeatureswecanimplementusingproxies.YouhavealsoseenhowanexternalwebservicecanbeboundtotheJBIbusandthenexposedasproxieswithinthebusitselfsothatothercomponentswithinthebuscanroutemessagesthroughtheseproxies.Thebuildingblocksdemonstratedinthischaptercanbeusedtosolveyourintegrationproblems.

Wewilllookintoamoreinterestingconcernintheservicesnetwork—versioningofservices,inthenextchapter.

Chapter14.WebServiceVersioningVersioningservice,especiallyofthewebservices,isatopicofheateddiscussionsinmanyoftheforumsandsites.Eventhoughtherearemanyapproachestothistopic,wecannotoftenfindanyconcreteguidelineorcodeshowingtheimplementation.Thisisbecausethetopicisnotsimple.Theterm"Versioning"meansdifferentthingstodifferentpeople,dependinguponthecontextinwhichtheyarespeaking.Forsome,versioningmeansawaytomanagecompatiblechangeintheserviceimplementationalone,withoutanymajorchangeintheservicedescription.However,forthosewhodefineservicesforalargecorporateenterprise,versioningisamechanismortoolwithoutwhichhecannotcontroltheeverincreasingcomplexityofanSOAecosystem.

TheeffectiveuseofanESBinfrastructureprovidesameanstosolvetheversioningproblemsandinthischapterwearegoingtolookattheworkingcodeinactiondemonstratinghowwecanversionthewebservices.

Wewilllookintothefollowingtopicsinparticular:

Thewhatandwhyofserviceversioning

VersioninginanSOAcontext—whatisrequired

Differentstrategiesinversioningthewebservices

Approachesinversioningthewebservices

Aserviceversioningsample—workingcodeinESB

ServiceVersioning—AMeanstoSOAVersioningisimportant,whetherwearedealingwithbinaryprogrammingparadigmssuchastheGlobalAssemblyCache(GAC)of.NETruntimeorwearedealingwithSOAinfrastructuressuchastheESB.HoweverwhenitcomestoSOA,versioningwillhaveaslightlydifferentmeaningwhichIwilltrytodescribeinthissection.

ServicesareAutonomousSOAisnowthebuzzword—peopleuseitineveryothercontext;everyonehastheirownbeliefsandunderstanding.Whateveritis,autonomybecomestheprimeconcerninanSOAimplementation.First,letusaskourselveswhywemovedawayfromouroldCORBAorourwell-knownJavaRMIarchitecturesforserviceimplementationandconsumption.LeavingasideallthevarieddefinitionsofSOAandthemanyadvantagesanSOAyields,autonomyisoneofthebestfeaturesSOAbringstothetableofboththeprovidersandconsumers.Serviceproviderscankeeponchangingtheirserviceimplementations,eithertoaddanewfunctionalityortoextendorenhancetheexistingfunctionality.Indoingso,serviceconsumersshouldbeunaffected;thatis,theyshouldn't

evenbeawarethatsomethinghaschanged.Needlesstosaythattheservicesdescriptionshouldn'tchange,noteventheserviceURLshouldchange.

ChangeistheOnlyConstantThingIfeverythingremainsstatic,itisanidealworldforanengineer,eventhoughanartistwouldthencursetheworld.However,timehasshownthattheonlyconstantthingintheworldischange.Networkschange,platformsandframeworkschange,operatingsystemschangeinversionsandsupportability,andserviceimplementationsalsochange.

AchangemaybetoenhancetheQOS,perhapstoimprovetheresponsetimebyintroducinganewalgorithminthecode.Changecanalsoaddanewfunctionalitytotheexistingserviceendpoints.Suchchangesareusuallymanageablebynotrevealingthechangetotheexternalworld,especiallytotheserviceconsumer.Sometimes,wemayalsoneedtointroduceorcutshortaparametertothealreadyexistingservicemethod.Insuchacasetheexistingconsumersmayhavetodosomechangesattheirendalso,tomakethestubscompatibletotheserver-sidechanges.Infactmanytimes,theserviceconsumershavetorebuildandrecompiletheirclient-sidestubsandadjusttheircallingcodetomakethemcomplywiththeremoteinterface.ForsmalldeploymentsthesecanbedonebydeveloperswiththebestdesignandcodepracticesandwiththehelpofIDEsandtools.However,thiswillturnouttobeanightmarewhenthenumberofserviceskeepsonincreasing,whichistypicalofeverygrowingenterprise.

AllPurposeInterfacesThereisalsothenotionofagenericorwholepurposeserviceinterface.Asampleisshowninthefollowingcode:

publicStringserviceMethod(StringserviceXml);

Theaboveinterfacetalksaboutagenericservice(eventhemethodnameisgeneric,"serviceMethod"),whichtakesagenericparameterandreturnsagainagenericvalue.PassingtheXMLinadocumentstyletoagenericmethodinterfaceliketheoneshownaboveisanexample.Here,wheneverachangeisrequiredweneedn'treflectthatintheinterface-level,buteverychangeishiddeninthestringformattedrequestandresponsemessages.Atfirstsightthismightseemtobeasolutiontothechangeproblem,butexperiencehasshownthatthisisinfactananti-patternintheSOAworld.Weloseallstatictypebindingwhichmeanseventhetoolswillnotfindoutanymismatchortypevalidationerrors.Thiswillberevealedonlyaftertheserviceinvocationasareactiveerrorscenario.

SOAVersioning—Don'tTouchtheAnti-PatternLetusconsideratypicalwebservicemethodsuchasthefollowing:

publicStringtransferFund(StringfromAccount,

StringtoAccount,doubleamount);

StringtoAccount,doubleamount);

Here,themethodwilltransferthefundfromoneaccounttoanother.Letusassumethatonefinedaywewanttochangetheservicetoacceptonemoreextraparameter,liketheoneshowninthefollowingcode:

PublicStringtransferFund(StringfromAccount,

StringtoAccount,doubleamount,String

transactionPassword);

Now,hereareasetofquestionsforthereader.Wemayormaynotanswerallthesequestionsbutatleastagreethatweidentifythepossiblecaveatstoourtraditionalthinking!Thefollowingarethequestionsforthereaderstothinkover.

1. Doweneedtoversionservicesoroperations?

ThefirstquestioninSOAiswhethertransferFundisaserviceoranoperation.WeneedtoappreciatethatawebserviceisdescribedbyaWSDLandaWSDLcancontainmultipleoperationsdefinedintheportType.Ifso,whentransferFundneedstoincludeonemoreparameterintherequest,hastheversionoftheoperationchangedortheversionoftheservicechanged?

2. Canweoverloadaservice?

Ifweconsiderobject-orientedprogramming,thesameclasscanincludeboth"versions"ofthetransferFundmethod—wecallitmethodoverloading.Fortunatelyorunfortunately,WSDLdoesn'tallowmethodoverloading.Nowweareleftwithfewotherstrategies(orhacks?)tocombatthechange,whichisdescribedinthenextpoint.

3. Newversionornewservice?

Tohandlethenewextraparameter,IcancreatethetransferFund02methodwhichwilltakeanextraparameterorrenametheservicenametosomethingdifferentliketransferFundSecurely.Whateverour

strategy,thequestionhereishavewecreatedanewversionoftheserviceoranentirelynewservice?

4. Willourinformationmodelsaveusfromschemachanges?

Letusconsideranewservice:

publicAddressgetAddress(CustomerInfo

customerInfo);

TheaboveservicewillreturnbackanAddressifyouprovidetheCustomerInfoofthecustomerwhoseAddresshastoberetrieved.Now,letuslookintoAddress.

publicclassAddress{

privateStringhouseNumber;

privateStringstreet;

privateStringcity;

}

Now,wechangetheAddresstoincludeanadditionalfieldtoalsotakecareofthezipcodeasshownhere:

publicclassAddress{

privateStringhouseNumber;

privateStringstreet;

privateStringcity;

privateStringzip;

}

DoyouthinkthischangehasintroducedanychangetothegetAddressservice?Apparentlynot,sincetheservicedefinitionremainsthesame,butinfactIhavealteredmydatatypewhichinturnwillmaketheexistingconsumercodebaseincompatiblewiththenewservice.

Sofarsogood,nowthefinalquestion—forscenariosthatwehaveseenabove,shouldwecreateanewversionoftheexistingserviceorshouldwedefineanewserviceitselfbynot

disturbingtheexistingone?

Ratherletusrestatetheabovepointsinthismanner—inSOA,servicesshouldn'tmutatefromversiontoversion.Thiswillsafeguardanyexistingconsumers.However,newservicescanbeintroducedwhichisnottoocomplicatedbecausenewserviceswillhavetheirownseparateendpoints.Moreover,irrespectiveofwhethertheconsumersareneworexisting,theywillusethenewendpointtoavailthenewservice.Atthesametimeservicescanalsobeenhancedorupgraded.AnenhancementcaninvolveincreasingtheQOSfeaturesoftheserviceorbringinginnewimplementationtechnologiesbehindthescenes,keepingtheserviceinterfaceuntouched.Whenyouupgradeaservice,youcannowdecidewhattodowiththe"oldversion"ofthesameservice.Ipurposelyusedthewords"oldversion"thistimebecauseversioningofservicesmakessenseinthecontextofenhancingorupgradingservicesonly,notinthecontextofintroducingnewservices.

TypescanInherit—WhynotMySchemasAgaininOOP,youcandefineabasetype(likeAnimal)andderivemultipletypes(likeCatandDog)fromthat.Thederivedclassesarealwaystypecompatibletothebasetype(YoucanalwayssubstituteanAnimalwithaCatoraDog).

W3CXMLschema's<extension>providesusameanstoextendXMLschemas.Howcanthisbeofanyusetoourwebservice?CanwesubstituteanAddressXMLinstancewhich

containsazipcodeelementinplaceofwhereaserviceexpectsanAddresswithoutthezipcode?Whethertheservicewillstillworkornotdependsonwhatextrahooksyouattachtoyourwebservicesinfrastructuretobridgetheschemamismatch.Hence,weacknowledgethefactthatschemasareextensibleandarealsoabletoversion.Butthatmightnotstraightawaymaptotheconceptofextendingversioningprinciplestoservices.

IfNotVersions,ThenWhatHavingdiscussedenoughaboutversioningaroundservices,letusnowlookintowhatisneededinanSOA.Weallagreethatmultipleflavor(variants)ofservicecanexistandifallofthemcoexist,weneedagoodgovernancemechanismalsotosatisfyconsumerrequestsaspertheagreeduponSLA.ThisiswhereanESB-basedroutingmechanismwilladdvalue.Theword"version"isverycommontothesoftwaredevelopersandso,wepreferstoretainthatwordinthediscussionsalso—topointtomultiplevariantsoftheservice.Letusnowlookintoversioningofservicesinthiscontext.

StrategytoVersionWebServiceGiventheproblemofchange,thenextthingistofindouttheexactmechanismtofollowtoversioncontroltheservices.Infact,wehavealreadyseenoneway,whichisthegenericstring

formattedmessagesapproach,butasdiscussed,thismaynotbethebestavailablemethod.Wewillnowlookintomultipleoptionsavailableforserviceversioning.

WhichLeveltoVersionOneimportantquestiontoanswerinserviceversioningisthelevelatwhichwehavetoversioncontrol.Bylevelwemeanwhetheratthewholeserviceinterface-levelorattheindividualservicemethod-level.PerhapsthisquestionisoutofcontextbecausewhenwespeakonSOAanditsconstituentservices,wealwaysmeansserviceswhicharecoarsegrained,whichareneverindividualfinegrainedmethodinvocations.Inotherwords,wealwaysspeakabout"transferfund","authorizecredit",or"validateservice"requestinSOA,butnotfinegrainedmethodssuchas"updatebalancecellinaccounttable".Thisfollowsthatservicescanbeversionedasawhole.Forexample,inafundtransferservicewecaneitherversioncontrolfortheservicefundtransferorfortheindividual,composedservicessuchaswithdrawalanddeposit.Toversioncontrolasawhole,weneedtoversionthefundtransferservice,notthecomposedfinegrainedmethods.

VersionControlinaSchemaAnXMLschemaisusedinawebservicedescriptiontodefinethemessageparametersexchangedbetweentheconsumersandproviders.TheXMLschemaalsodefinesanamespacewhichdifferentiatesoneschemafromanother.Moreover,a

schemaalsoprovidesamechanismforextensibility.Thus,aXMLschemaisadoubleedgedsword.Ononeside,itgivestheflexibilityofextensionandontheothersideitgivesamechanismtoconstraintorseparateoutbetweenextensions.Letuslookintoasampleschemaandexplainthis.

<?xmlversion="1.0"encoding="ISO-8859-1"?>

<xs:schema

xmlns:xs="http://www.w3.org/2001/XMLSchema"

targetNamespace="http://www.product.org">

<xs:complexTypename="employee">

<xs:sequence>

<xs:elementname="firstName"type="xs:string">

<xs:elementname="lastName"type="xs:string">

<xs:anynamespace="##any"processContents="lax"

minOccurs="0"maxOccurs="unbounded">

<xs:sequence>

</xs:complexType>

<xs:schema>

TheaboveisanextensibleXMLschema.ThefirstNameandlastNameelementsareboundwhereasitprovidesanextensionmechanismtoaddadditionalconstructsafterthelastName(forexample,BinilDasMr,CraigMaretPhD,andsoon)whilestillremainingvalidbasedontheoverallschemadefinition.Atthesametime,thetargetNamespacemechanismalsohelpsustoseparateoutdifferentschemas,andthustodifferentiatebetweenschemaconstrainedXMLdata.

targetNamespaceforWSDL

AWSDLdocumentisthedescriptionofawebserviceandhasadefinitionselementthatcontainsthetypes,message,portType,binding,andserviceelements.

Forthedefinitionselement,targetNamespaceisthenamespaceforinformationaboutthereferredservice.OneWSDLdocumentcanimportotherWSDLdocuments,andsettingtargetNamespacetoauniquevalueensuresthatthenamespacesdonotclash.ThedefaultnamespaceoftheWSDLdocumentisxmlns,anditissettohttp://schemas.xmlsoap.org/wsdl/.AlltheWSDLelements,suchasdefinitions,typesandmessagesresideinthisnamespace.xmlns:xsdandxmlns:soaparethestandardnamespacedefinitionsusedforspecifyingSOAP-specificinformationaswellasdatatypes.xmlns:tnsstandsforthisnamespace.

TheWSDLsaregeneratedoutoftheserviceinterfaces.TheseinterfacesmaybeinJavaor.NET.WhentoolsgeneratetheWSDL,theywillhavetheirdefaultstrategyonwhatvaluetoputforthetargetNamespaceattribute.Manyatimes,thiscanbeoverriddenbythetools.ApacheAxisWSDL2JavaandJava2WSDLdothis.Hence,targetNamespaceisanattributewhichwecancontrolifrequired.ThetargetNamespacecanbegivenvaluesinmultipleformats,dependinguponwhichwaywewanttocontrol.Examplesaregivenhere:

targetNamespace=http://www.binildas.com/types/products/v1/1

targetNamespace=http://www.binildas.com/2006/12/30/products

Thisalsoprovidesanexcellentmechanismtoversioncontrolservicesandwewilldemonstratethisinexampleslaterinthischapter.

VersionParameterIncludingaversionparameterisanothermethod.Thisspecialparameterisusuallypassedthroughtheheadersofthewebservicerequest.Itisalsopossibletoincludethisparameterinthemessagepayload(orbodycontent).Ineitherform,inordertomakethismechanismworkweneedtopassthevaluefortheversionparameteralongwitheveryrequest.AsampleSOAPrequestwithaversionparameterintheheaderisshowninthefollowingcode:

<soap:Envelope

xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"

<soap:Header>

<Version

xmlns="http://product.services/binildas.com">

</Version>

</soap:Header>

<soap:Body>

....

</soap:Body>

</soap:Envelope>

Asdiscussedbefore,thesamecanbeincludedinthebodyasshowninthefollowingcode:

<soap:Envelope

xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"

<soap:Header>

</soap:Header>

<soap:Body>

<svc:hello

xmlns:svc="http://product.services/binildas.com">

<Version

xmlns="http://product.services/binildas.com">

</Version>

....

</svc:hello>

</soap:Body>

</soap:Envelope>

WebServiceVersioningApproachesWehaveseenafewstrategiesofwebserviceversioning.Letusnowlookatsomeapproachesofimplementingthoseversioningstrategies.

CovenantAcovenantisanif-then-elsewayofversioningapproach.Thiscanbedoneusingmultiplestrategieswhichwesawearlier.Inanystrategy,thecovenantapproachlooksforsomeifs,anddependingupontheoutcomeoftheconditionasuitablethenclausewillbeexecuted.Itcanalsohaveanelseoradefaultclause.Hencethisapproachisusuallycombinedwitha

versioningflagandthisflagcanbeeitherintheformofaversionparameterorintheformofaversionsensitivevalueinthetargetNamespace.Thisisshowninthefollowingfigure:

AcovenantisusuallyexposedinaSingleEndpointAddress.Hence,allConsumerswillsendmessagestothesameaddress.DependinguponwhichversionoftheservicecontracttheConsumerisusingasuitableversionflagwillbepassedeitherasaversionparameterorthroughthetargetNamespace.Thecovenantusuallyimplementsacontent-basedrouter.Acontent-basedrouterisusedtorouteeachmessagetothecorrectrecipientbasedonthemessagecontent.TheroutingcanbebasedonanumberofcriteriasuchastheexistenceofaversionparameterandtheversioninfointargetNamespace,.TheadvantageofthecovenantapproachisthatConsumersareunawarethatmultipleserviceversionscoexistattheProvider'send.Hencetheyneedn'tadjusttheiraddresstoroutetospecificserviceversions.Instead,theywillplacetheirversionflaginthemessageandsendittothesameaddress.Itisuptothecovenanttoredirectthemessagetotheappropriateversionoftheservice.

MultipleEndpointAddressesIntheMultipleEndpointAddressapproach,eachversionofthewebserviceisallottedaseparateendpointaddress,andtheyarethenboundtoalookupmechanismlikearegistry.Now,theConsumerhastodecidetheendpointaddressforserviceinvocationbylookingattheServiceRegistry,andcrossmatchingtheversionofinterest.ThentheConsumersendsmessagestotheselectedendpointaddressofinterest.ThischannelwillroutetheMessagestraighttotheexactversionoftheservice.Theschemaisshowninthefollowingfigure:

WebServiceVersioningSampleusingESBWediscussedthetheoryofwebserviceversioning,nowitistimetoputthatincode.Letusdothatwiththehelpofasampleusecase.Onethingtobenotedhereisthatto

implementthesamplewemakeuseofEIPsbuildingblockswhicharedescribedindetailinachapteroftheirown.

SampleUseCaseThesampleusecaseisaboutsettinguptheJBIcomponentstoeffectivelyenabletheversioningmechanismintheservices.AllthesecomponentsareconfiguredintheESB.AnexternalclientinteractswiththeESBthustestingtheversioningmechanism.TheESBisboundtothedifferentversionsofservices,whicharedefinedexternalandremotetotheESB.TheESBwillapplytheversioningrulesandroutetherequeststotherespectiveversionoftheservice.Thesampleusecaseisillustratedhereinthefollowingfigure:

Infactthissampleisnotascomplicatedasthefiguremakeitlook.Wewillseetheindividualcomponentsfirstandunderstandtheflow.

JMSclient:Inthissample,weusetheJMSchanneltosendwebservicerequests.TheJMSClientreadstheSOAPrequestmessagefromafileandsendsthemessagetotheJMSConsumerqueueconfiguredintheESB.One

pointtobenotedhereisthatwearegoingtousethetargetNamespacemechanismoftheWSDLtoimplementtheserviceversioning.IfweopentheSOAPrequest,wecanseehowwehavedesignedtheSOAPrequestsoastoincludeaversionspecificvalueforthenamespaceattribute.ThevaluecorrespondstothetargetNamespaceattributeofWSDLfortheSOAPrequest.

JMSconsumer:TheJMSConsumerisaservicemix-jmscomponentwhichallowsyoutosendJMSmessagestotheconfiguredqueue.Aconsumerrolefortheservicemix-jmscomponentimpliesthecomponentisaconsumertotheNMR.AnymessagescomingtothequeuewillbetransferredtothetargetServiceattributefortheJMSConsumer.

WhiteSpacetransformer:AvalidSOAPrequestcancomeinseveralforms,allinasinglelonglineorseparatedoutintomultiplelines,formattedwithindentationsandspaces.TomakethecontentreadyforanXPathquerymatchlaterintheflow,weusetheextraneousWhiteSpaceTransformercomponentwhichwilltrimoutallextraneouswhitespacesfromtheSOAPrequestpayloadandnormalizeitintoasingleline.

Content-basedrouter:TheContentBasedRouterisusedforallkindsofcontent-basedrouting.WeearlierdiscussedthatwehavedesignedtheSOAPrequestsoastoincludeaversionspecificvalueinthetargetNamespaceattributefortheSOAPrequest.HencenowwewilluseaContentBasedRouterwhichisaservicemix-eipcomponent.ThiscomponentwillinspectthevalueforthenamespaceattributecorrespondingtothetargetNamespaceattributeoftheWSDLembeddedintheSOAPrequestandseethematchingruleconfiguredatthecomponent-level.Dependinguponthematch,theContentBasedRouterwillroutetheSOAPrequestmessagetoanyoneofthesetofTransformerPipelinesconfigured.

Transformerpipeline:ThepipelineisastandardEIPcomponentandhenceisavailablereadilyasastandardJBIEIPcomponentinServiceMix.ThepipelinecomponentisanintegrationbridgebetweenanIn-Only(orRobust-In-Only)MEPandanIn-OutMEP.ByreceivinganIn-OnlyMEPbythepipeline,itwillsendtheinputmessageinanIn-OutMEPtothetransformerdestinationandtheninturnforwardtheresponseinanIn-OnlyMEPtothetargetdestination.Asperthat,ouraimhereistosendthemessagetoanIn-OutMEPcomponent(acontentretrieverinourcase)andthentoroutetheoutmessagefromthatcomponenttothenextchainintheflow(whichagaininourcaseisasecondpipeline).

Contentretriever:ThefunctionalityofthiscomponentistoextractthepayloadpartfromtheincomingSOAPrequest.Hence,wetrimouttheSOAPenvelopeandbodytags,andextractonlythecontentswithinthebodyelementtobesenttothenextcomponent.WesaidthatweneedtoinvokeawebserviceandyoumightwonderwhywewanttoextractthepayloadaloneratherthansendingthewholeSOAPrequesttothetargetwebservice.ThereasonwhywearedoingthiswillbeevidentwhenwereviewtheHTTPProvider.ContentRetrieverwillsendtheoutpartofthemessagebacktothetransformerpipeline.TheTransformerPipelinewillroutethismessagetothenextcomponentinthechain,whichistheServicePipeline.

Servicepipeline:OuraimhereistosendtheinputmessageinanIn-OutMEPtothenextcomponentwhichistheHTTPProvider.TheninturnforwardtheresponseinanIn-OnlyMEPtothetargetdestination,whichistheoutputJMSqueue.

HTTPprovider:AHTTPProviderroleimpliesthattheNMRistheconsumertothecomponent.Hence,theHTTPProviderislinkedwiththeRemoteWebServicesothatanyrequestcomingtotheHTTPProvidercanberoutedtothewebservice.WhentheHTTPProvidersendsarequesttothewebservice,itneedstospecifyaSOAPactionintherequestheader.Tofacilitatethiswehavetwoattributesnamely,soapandsoapActionattheHTTPProvider-level.AtruevalueforsoapattributesissupposedtowrapthemessagebodyinaSOAPenvelopewhereasthevalueforsoapActionwillbeembeddedastheSOAPactionintherequestheader.Forsomereason,ifwespecifythesoapActionattributealone,servicemix-httpdoesnotforwardtheSOAPactionheader.HencewearespecifyingsoapandsoapActiontogether.However,soapwillwraptherequestintheSOAPenvelope.Wedon'twantthebodycontentwrappedintwolevelsofSOAPenvelope.ThatiswhyintheContentRetrievercomponent(wealreadyhaveseenthisshortwhileago)weextractonlythecontentswithinthebodyelementtobesendtothenextcomponent.

Remotewebservice:Thisisanormalwebservicewhichcanbedeployedinanywebcontainerinfrastructure.

JMSprovider:TheSOAPresponseisplacedbackinthequeueconfiguredintheJMSProvidercomponentfromwheretheclientprogrampicksupthemessage.

HTTPconsumer:TheHTTPConsumercomponentsconfiguredherearejusttohelpyoutosendarbitrarymessagestothesamplesetupforanyad-hoctesting.

Wehavenowseenthemajorcomponentsconfiguredforthesampleapplicationandhowthemessageflowsthroughthem.Wealsohaveafewmoresettingssothatwecanactuallydemonstratethatwecancontrolmultipleversionsofwebservicestobeexposedtoclientsinthecovenant-basedsettings.Letuslookthatnow.

Infact,wehavetwoSOAPrequests,eachhavingtwodifferentvaluesforthetargetNamespaceattribute.WealsohavetwoJMSclientprogramssothatthereaderscaneasilytestthesetwoSOAPrequestsontheESB.TomakesuretherequestsareroutedseparatelytodifferentwebservicesbasedonthevalueoftargetNamespaceattribute,wealsohavetwowebserviceshostedandboundtotheESBinfrastructure.

Nowwewillmoveontothedetailsoftheconfigurationandothersettingsforthedemonstration.Forthat,alsohavealookatthefilesandfolderstructureorganizationwehavesothatwecanhostandmanagetwoversionsofwebserviceinthedemosetup.

Thefigureshowsonlythefilesrequiredforthedemosetup.Thetop-levelbuildiscapableofcallingthebuildfilesinthechildprojectfoldersandthuscanbuildtheentiredemoinasinglego.Thiswillthencreatemanyintermediateandfinalfoldersandartifactswhicharenotshownhere.

ConfigureComponentsinESBInthesampleusecasesectionyouhaveseenthevariouscomponentsusedforthedemo,andyouhavealsoseentheflowofmessage.LetusfollowthesameorderforcomponentsandseehowtheyareconfiguredinServiceMixsothatyoucaneasilycorrelatetotheflowweexplainedearlier.

JMSclient:TherearetwoversionsoftheJMSclients.Theyare:

ch14\WebServiceVersioning\JMSClient20061231.java

ch14\WebServiceVersioning\JMSClient20070101.java

BoththeseclientprogramsaresimilarexceptthefactthatJMSClient20061231.javareferstoSoapRequest20061231.xmlwhereasJMSClient20070101.javareferstoSoapRequest20070101.xml.ThecodeforJMSClient20061231isshownasfollows:

publicclassJMSClient20061231

{

privatestaticfinalStringREQUEST_FILE=

"SoapRequest20061231.xml";

publicstaticvoidmain(String[]args)throws

Exception

{

ActiveMQConnectionFactoryfactory=new

ActiveMQConnectionFactory("tcp:/localhost:61616");

ActiveMQQueuepubTopic=new

ActiveMQQueue("queue/A");

ActiveMQQueuesubTopic=new

ActiveMQQueue("queue/B");

Connectionconnection=

factory.createConnection();

Sessionsession=

connection.createSession(false,

Session.AUTO_ACKNOWLEDGE);

MessageProducerproducer=

session.createProducer(pubTopic);

MessageConsumerconsumer=

session.createConsumer(subTopic);

connection.start();

InputStreaminputStream=

JMSClient20061231.class.

getClass().getResourceAsStream(REQUEST_FILE);

intavailable=inputStream.available();

byte[]bytes=newbyte[available];

inputStream.read(bytes);

inputStream.close();

StringrequestString=newString(bytes);

producer.send(session.createTextMessage(requestString));

TextMessagetextMessage=(TextMessage)

consumer.receive(1000*10);

if(textMessage==null)

{

System.out.println("Responsetimedout.");

}

else

{

System.out.println("Responsewas:"+

textMessage.getText());

}

connection.close();

}

}

TheprogramopensthefileSoapRequest20061231.xml,readsthecontent,andthensendsthecontenttotheJMSqueueconfiguredasthewebservicegatewaychannelattheESBend.LetusalsolookattheSOAPrequestformattounderstandhowweplaceavalueforthenamespaceoftheXMLelementcorrespondingtothetargetNamespaceattributeofWSDL.Forthis,SoapRequest20061231.xmlcontentsareshownasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<soapenv:Envelope

xmlns:soapenv="http://schemas.xmlsoap.org/

soap/envelope/"

xmlns:xsd="http://www.w3.org/2001/XMLSchema"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-

instance">

<soapenv:Body>

<ns1:hellosoapenv:encodingStyle=

"http://schemas.xmlsoap.org/soap/encoding/"

xmlns:ns1="http://version20061231.ws.

xmlns:ns1="http://version20061231.ws.

servicemix.esb.binildas.com">

<in0xsi:type="soapenc:string"

xmlns:soapenc="http://schemas.xmlsoap.org/

soap/encoding/">

Binil

</in0>

</ns1:hello>

</soapenv:Body

</soapenv:Envelope>

Letuspayattentiontothens1namespace.Wehavegivenavalueof"http://version20061231.ws.servicemix.esb.binildas.com"forthisnamespaceandwearegoingtousethistweaktoversioncontroltheservices.YoumaywanttohavealookattheWSDLfortheremotewebservicealsotocorrelatehowthens1namespacecorrespondstothetargetNamespaceattributeofWSDL.

JMSconsumer:JMSconsumerisaservicemix-jmscomponentconfiguredintheconsumerrole.Weconfigurequeue"A"astheinputqueueforallthetestmessages.Wehavealsoconfiguredtest:extraneousWhiteSpaceTransformerasthetargetServiceforthisJMSconsumersothattheJMSconsumerwillrouteanymessagescomingtothequeue"A"totheextraneousWhiteSpaceTransformercomponent.Thisisshowninthefollowingcode:

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpoint

service="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="test:

extraneousWhiteSpaceTransformer"

defaultMep="http://www.w3.org/2004/08/

wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

Whitespacetransformer:ThewhitespacetransformerisaServiceMixXsltComponent.Itusesastylesheettoremoveallextraneouswhitespacesfromthemessage.Thetrimmedmessageisthenroutedtothenextcomponent,whichisthetest:router.

<sm:activationSpec

componentName="extraneousWhiteSpaceTransformer"

service="test:extraneousWhiteSpaceTransformer"

destinationService="test:router">

<sm:component>

<bean

class="org.apache.servicemix.components.

xslt.XsltComponent">

<propertyname="xsltResource"

value="RemoveExtraneousWhiteSpace.xsl">

<bean>

</sm:component>

</sm:activationSpec>

TheXsltComponentusesastylesheettostripoutallextraneouswhitespacesfromthemessage.Thestylesheetisshownasfollows:

<?xmlversion="1.0"encoding="utf-8"?>

<xsl:stylesheet

xmlns:xsl="http://www.w3.org/1999/XSL/

Transform"version="1.0">

<xsl:outputmethod="xml"version="1.0"

indent="no"/>

<xsl:strip-spaceelements="*">

<xsl:preserve-spaceelements="xsl:text">

<xsl:template

match="/|*|@*|processing-instruction()">

<xsl:copy>

<xsl:apply-templatesselect="@*|node()

[not(self::comment())]">

<xsl:copy>

</xsl:template>

</xsl:stylesheet>

Content-basedrouter:Thisisthecoreofthedemonstrationsetupandthisiswherethedecisionastowhichversionoftheserviceistobeinvokedtakesplace.Letuslookatthiscomponentindetail.

<eip:content-based-router

service="test:router"endpoint="endpoint">

<eip:rules>

<eip:routing-rule>

<eip:predicate>

<eip:xpath-predicate

xpath="number(substring-before(

substring-after(namespace-uri-for-prefix(

substring-before(name(/*/child::node()/

child::node()),':'),/*/child::node()/

child::node()),'http://version'),

'.ws.servicemix.esb.binildas.com'))&lt;

20061231">

<eip:predicate>

<eip:target>

<eip:exchange-targetservice="test:

pipelineTransformBefore20061231">

<eip:target>

</eip:routing-rule>

<eip:routing-rule>

<eip:predicate>

<eip:xpath-predicate

xpath="number(substring-before(

substring-after(namespace-uri-for-prefix(

substring-before(name(/*/child::node()/

child::node()),':'),/*/child::node()/

child::node()),'http://version'),

'.ws.servicemix.esb.binildas.com'))=

20061231">

<eip:predicate>

<eip:target>

<eip:exchange-targetservice="test:

pipelineTransform20061231">

<eip:target>

</eip:routing-rule>

<eip:routing-rule>

<eip:predicate>

<eip:xpath-predicate

xpath="number(substring-before(

substring-after(namespace-uri-for-prefix(

substring-before(name(/*/child::node()/

child::node()),':'),/*/child::node()/

child::node()),'http://version'),

'.ws.servicemix.esb.binildas.com'))&gt;

20061231">

<eip:predicate>

<eip:target>

<eip:exchange-target

service="test:pipelineTransformAfter20061231"

>

<eip:target>

</eip:routing-rule>

<eip:routing-rule>

<eip:target>

<eip:exchange-target

service="test:pipelineTransformAfter20061231"

>

<eip:target>

</eip:routing-rule>

</eip:rules>

</eip:content-based-router>

Theabovecontent-basedrouterhasthreeconditionaltargetsandadefaulttarget.Toevaluatethecontent,therouterusestheXPathpredicatewherewecanpluginourrulesintheXPathformat.

Therulewhichwepluginhereisrepeatedagain:

number(substring-before(substring-

after(namespace-uri-for-prefix(substring-

before(name(/*/child::node()/child::node()),

':'),/*/child::node()/child::node()),

'http://version'),

'.ws.servicemix.esb.binildas.com'))

ThisrulehastobeunderstoodinrelationtotheSOAPrequestwhichwehavealreadyseen.Letusrepeattherelevantportionagainhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<soapenv:Envelope…>

<soapenv:Body>

<ns1:hello

xmlns:ns1="http://version20061231.ws.

servicemix.esb.binildas.com"…>

<in0xsi:type="soapenc:string"

xmlns:soapenc="http://schemas.xmlsoap.org/

soap/encoding/">Binil</in0>

</ns1:hello>

</soapenv:Body

</soapenv:Envelope>

TheXPathpredicateshownaboveisintendedtocuttheversionpartalonefromthenamespaceattributeintheSOAPrequest.Wehaveappendedyear,monthanddateinintegerformtogethertoformaneasyrepresentationofversion.Ifrequired,wecanalsoappendthetimestampportiontotheversionattributetomakeitmoreagile!Inanycase,wetaketheversionvalueandcompareitintherouter.Intheaboverouter,wehavefollowingpseudocodedrule:

if(${version}<20061231)

target:test:pipelineTransformBefore20061231

else

if(${version}=20061231)

target:test:pipelineTransform20061231

else

if(${version}>20061231)

target:test:pipelineTransformAfter20061231

else

target:test:pipelineTransformAfter20061231

Hence,dependinguponwhichversiontheSOAPrequestistargetedto,thecontent-basedrouterwillroutetherequesttotheappropriatepipelinetransform.

WehaveprovidedtwoSOAPrequestfilesfortesting.Theyare:

SoapRequest20061231.xml

SoapRequest20070101.xml

Asisevidentfromtheirnames,SoapRequest20061231.xmlhas20061231embeddedastheversioninthebodywhereasSoapRequest20070101.xmlhas20070101asitsversion.Thereadersarefreetochangethisversionvaluestotheirownfigurestotestwhetherornottherouterbehavesappropriately.Ifrequired,thereaderscanalsoaddmoreclausestotherulesinthecontent-basedrouterandunderstandthebehavior.

Transformerpipeline:ThepipelineisastandardEIPcomponentandisanintegrationbridgebetweenanIn-Only(orRobust-In-Only)MEPandanIn-OutMEP.ByreceivinganIn-OnlyMEPbythepipeline,itwillsendtheinputmessageinanIn-OutMEPtothetransformerdestinationandtheninturnforwardtheresponseinanIn-OnlyMEPtothetargetdestination.Letuslookatourpipelineconfigurationshowninthefollowingcode:

<eip:pipeline

service="test:pipelineTransformBefore20061231"

endpoint="pipelineTransformBefore20061231">

<eip:transformer>

<eip:exchange-target

service="test:soapContentRetreiver">

<eip:transformer>

<eip:target>

<eip:exchange-target

service="test:pipelineServiceBefore20061231"

>

<eip:target>

</eip:pipeline>

ThepipelinereceivestheSOAPrequestinanIn-OnlyMEP.Thisrequestisthenroutedtothetest:soapContentRetreivertargetinanIn-Out

MEP.TheresponsefromsoapContentRetreiveristhenroutedtotheexchange-targetofthepipeline,whichisanotherpipelineinthechain,test:pipelineServiceBefore20061231.

Contentretriever:ThefunctionalityofthiscomponentistoextractthepayloadpartfromtheincomingSOAPrequest.So,wetrimouttheSOAPenvelopeandbodytags,andextractonlythecontentswithinthebodyelementtobesenttothenextcomponent.WeuseaServiceMixXsltComponentasthecontentretriever.Itusesastylesheettoremoveallextraneouswhitespacesfromthemessage.Thetrimmedmessageisthenroutedtotheconsumerforthiscomponentwhichistheprevioustransformerpipeline.

<sm:activationSpec

componentName="soapContentRetreiver"

service="test:soapContentRetreiver">

<sm:component>

<bean

class="org.apache.servicemix.components.

xslt.XsltComponent">

<propertyname="xsltResource"

value="SoapRequest-To-Request.xsl">

<bean>

</sm:component>

</sm:activationSpec>

ThisXsltComponentalsousesastylesheettoextractthepayloadfromtheSOAPmessage.Thestylesheetisshownasfollows:

<xsl:stylesheetversion="1.0"

xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

xmlns:soapenv="http://schemas.xmlsoap.org/soap/

envelope/">

<xsl:outputmethod="xml">

<xsl:templatematch="">

<xsl:copy-of

select="soapenv:Envelope/soapenv:Body/*">

<xsl:template>

</xsl:stylesheet>

Theoutputofthiscomponentisshownasfollows:

<ns1:hello

soapenv:encodingStyle="http://schemas.xmlsoap.org/

soap/encoding/"

xmlns:ns1="http://version20061231.ws.

servicemix.esb.binildas.com">

<in0xsi:type="soapenc:string"

xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/">

Binil

</in0>

</ns1:hello>

Servicepipeline:Thiscomponentisverysimilartothetransformerpipelineseenabove.Letuslookattheconfigurationandthenunderstanditmore:

<eip:pipeline

service="test:pipelineServiceBefore20061231"

endpoint="pipelineServiceBefore20061231">

<eip:transformer>

<eip:exchange-target

service="version20061231:IHelloWebService">

<eip:transformer>

<eip:target>

<eip:exchange-target

service="test:MyProviderService">

<eip:target>

</eip:pipeline>

ThispipelinewillsendtheSOAPpayloadalone(withouttheSOAPenvelope)asanIn-OutMEPtotheeip:exchange-targetwhichisversion20061231:IHelloWebService.Anyresponseisthenroutedtothetest:MyProviderService,whichistheoutputqueuefortheclient.

HTTPprovider:TheHTTPproviderisaservicemix-httpusedforHTTPorSOAPbindingofservicesandcomponentsintotheServiceMixNMR.AproviderroleimpliesthattheNMRistheconsumertothecomponent.Hence,theNMRsendsoutanIn-OuttotheHTTPproviderand

theHTTPproviderinturnroutesthemessagetotheremotewebservice.ThewebservicegetsinvokedandtheresponsereceivedisroutedbacktotheconsumeroftheHTTPproviderwhichistheservicepipelinedescribedabove.TheHTTPproviderconfigurationisshownasfollows:

<http:endpoint

service="version20061231:IHelloWebService"

endpoint="HelloWebService"role="provider"

locationURI="http://localhost:8080/

AxisEndToEnd20061231/services/

HelloWebService20061231"soap="true"

soapAction=""

wsdlResource="http://localhost:8080/

AxisEndToEnd20061231/services/

HelloWebService20061231?WSDL"/>

Here,thelocationURIreferstotheactualURLwherethewebserviceishosted.Aswehavetwoversionsofthewebserviceshostedtotesttheversionfunctionality,wealsohaveanotherHTTPproviderpointingtotheotherwebserviceversionsasshowninthefollowingcode:

<http:endpoint

service="version20070101:IHelloWebService"

endpoint="HelloWebService"role="provider"

locationURI="http://localhost:8080/

AxisEndToEnd20070101/services/

HelloWebService20070101"soap="true"

soapAction=""

wsdlResource="http://localhost:8080/

AxisEndToEnd20070101/services/

HelloWebService20070101?WSDL"/>

Remotewebservice:Thissectionneedssomedetailedexplanation,asweneedtolookintomechanismsonhookingtheversioncontrolintoourdevelopmentengineeringprocessitself.

WehaveseenthatthereareoptionstosetthetargetNamespaceattributeontheWSDL.Itisbetterto

hookthistothetoolinfrastructureassociatedwithwebservicegenerationandmosttoolsincludingtheApacheAxisprovidesmechanismstodothis.Letuslookintothatnow.

AxisprovidestheJavaorg.apache.axis.wsdl.Java2WSDLclasstohelpusingeneratingWSDLfromtheJavainterfacesusedforcreatingthewebservice.TheWSDLgenerationcanbecontrolledusingtheparameters.Twoparametersthatareimportanttousarethefollowing:

-n,--namespace<targetnamespace>

indicatesthenameofthetargetnamespaceoftheWSDL.

-p,--PkgToNS<package><namespace>

indicatesthemappingofapackagetoanamespace.

Ifapackageisencounteredthatdoesnothaveanamespace,theJava2WSDLemitterwillgenerateasuitablenamespacename.Thisoptionmaybespecifiedmultipletimes.Bydefault,Java2WSDLwilltakethepackagenameofthewebserviceinterfaceclass.

Now,weneedtoversioncontrolthewebserviceexposureaswellasthewholewebservicegenerationprocess.Hence,wehavearrangedourwebserviceartifacts(sourcefiles,andtheirpackagenamestoo)inafolderstructurewhichrepresentstheversion.Bydoingthatwedon'tneedtocontrolfurtherthe

Java2WSDLprocessusingtheaboveparameters,insteadthe"versioned"packagenameoftheclassesisusedtodefinethetargetNamespaceattributeontheWSDL.

Wehavetwoversions,namely20061231and20070101,referringtothetwoversionsoftheservice,onedefinedonthe2007NewYear'seveandtheotheronthenewyearitself.

LetuslookatthisintheWSDLsgeneratedforthetwowebserviceswehave:

InHelloWebService20061231.wsdlwehavethefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

targetNamespace="http://version20061231.ws.

servicemix.esb.binildas.com"…>

<wsdl:types>

<schemaelementFormDefault="qualified"

targetNamespace="http://version20061231.ws.

servicemix.esb.binildas.com"

xmlns="http://www.w3.org/2001/XMLSchema">

</schema>

</wsdl:types>

<wsdl:messagename="helloResponse">

<!--othercodegoeshere-->

</wsdl:message>

<wsdl:portTypename="IHelloWeb">

<!--othercodegoeshere-->

</wsdl:portType>

<wsdl:binding

name="HelloWebService20061231SoapBinding"

type="impl:IHelloWeb">

<!--othercodegoeshere-->

</wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebService20061231SoapBinding"

name="HelloWebService20061231">

<wsdlsoap:address

location="http://localhost:8080/

AxisEndToEnd20061231/services/

HelloWebService20061231">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

InHelloWebService20070101.wsdl,wehavethefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<wsdl:definitions

targetNamespace="http://version20070101.ws.

servicemix.esb.binildas.com"...>

<wsdl:types>

<schemaelementFormDefault="qualified"

targetNamespace="http://version20070101.ws.

servicemix.esb.binildas.com"

xmlns="http://www.w3.org/2001/XMLSchema">

</schema>

</wsdl:types>

<wsdl:messagename="helloRequest">

<!--othercodegoeshere-->

</wsdl:message>

<wsdl:portTypename="IHelloWeb">

<!--othercodegoeshere-->

</wsdl:portType>

<wsdl:binding

name="HelloWebService20070101SoapBinding"

type="impl:IHelloWeb">

<!--othercodegoeshere-->

</wsdl:binding>

<wsdl:servicename="IHelloWebService">

<wsdl:port

binding="impl:HelloWebService20070101SoapBinding"

name="HelloWebService20070101">

<wsdlsoap:address

location="http://localhost:8080/

AxisEndToEnd20070101/services/

HelloWebService20070101">

<wsdl:port>

</wsdl:service>

</wsdl:definitions>

IfyouobservetheseWSDLfilescloselyyoucanseethatthewsdlsoap:addresspointstodifferentaddressesfordifferentversionsoftheservice.IfweexposetheWSDLassuchtoconsumers,thentheconsumerswillbetemptedtoaccessthewebserviceusingthe"Multipleendpointaddress"approach.However,wewanttodemonstratethecovenant-basedapproachandforthatwecaneditthewsdlsoap:addresselementintheWSDLsofboththewebservicestopointtothesameendpointaddress(theJMSconsumeraddressasisinourcase,oraHTTPconsumeraddress).Ifso,ourcontent-basedrouterwilldotherest.

JMSprovider:TheJMSproviderissimilartotheJMSconsumeralreadydiscussedandtheconfigurationislistedasfollows:

<jms:endpoint

service="test:MyProviderService"

endpoint="myProvider"role="provider"

soap="false"destinationStyle="queue"

jmsProviderDestinationName="queue/B"

connectionFactory="#connectionFactory"/>

Here,werefertheoutputqueueas"B".Thisisthequeueto

wheretheServicepipelinetargetstheSOAPresponsefromtheremotewebservice.TheJMSclientcanretrievetheresponsefromthisqueue.

DeployandRuntheSampleTobuildtheentiresample,itiseasiertochangedirectorytothetop-levelfolderandexecutethebuild.xmlfileprovidedthere.Asafirststep,ifyouhaven'tdoneitbefore,findexamples.propertiesfileprovidedalongwiththesampleandchangethepathsaccordinglytomatchyourdevelopmentenvironment.Thenexecutethefollowing:

cdch14\WebServiceVersioning

ant

Thiswillbuildthefollowingbothversionsofwebserviceandplacethedeployablewarfileinthedistfolderasshownasfollows:

ch14\WebServiceVersioning\01_WebService20061231\d

ist\AxisEndToEnd20061231.war

ch14\WebServiceVersioning\02_WebService20070101\d

ist\AxisEndToEnd20070101.war

Youcantransferthesewarfilesintothewebappsfolderofyourfavoritewebcontainerandrestartthewebserver.MakesureyourwebservicesaredeployedcorrectlybytryingoutthefollowingURLs:

http://localhost:8080/AxisEndToEnd20061231

/services/HelloWebService20061231?WSDL

http://localhost:8080/AxisEndToEnd20070101

/services/HelloWebService20070101?WSDL

Nowtherearealsotestclientsprovidedforyoutotestthetwoversionsofthewebservice.Totestthat,dothefollowing:

Totesttheversion20061231oftheservice,executethefollowingcommands:

cd

ch14\WebServiceVersioning\01_WebService20061231

antrun

Totesttheversion20070101oftheservice,executethefollowingcommands:

cd

ch14\WebServiceVersioning\02_WebService20070101

antrun

Asthesecondstep,youneedtobringupyourServiceMixESB.Beforedoingthatyouhavetoplug-intheSaxonXPathFactoryclasstotheJavaruntime.Thiscanbedoneintwosteps:

PlacetheSaxonjarsin%SERVICEMIX_HOME%\lib\optionalfolder.

Inthe%SERVICEMIX_HOME%\bin\servicemix.batfile,addthefollowingentry:

setBOOT_OPTS=%BOOT_OPTS%-Djavax.xml.xpath.XPathFactory:http://java.sun.c

om/jaxp/xpath/dom="net.sf.saxon.xpath.XPathFact

oryImpl"

NowbringupServiceMixbyexecutingthefollowingcommands:

cdch14\WebServiceVersioning

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

YourwebserviceandESBarereadynowtoserveclients.Twoclientsareprovidedtotestthewebservice.Youcantestthembyexecutingthefollowingcommands:

cdch14\WebServiceVersioning

antrun1

and

cdch14\WebServiceVersioning

antrun2

run1willtestthewebservicerequestingversion20061231andrun2willtestversion20070101.Boththeseclientswillsendmessagestothecovenantandthecovenantwillroutetherequeststodifferentversionsofthewebservice.

ForyourconveniencewehavealsoprovidedtwoHTTPclientswhichwilldirectlysendrequeststothedifferentversionsofthewebserviceendpointaddressesconfiguredin

theESB.Theyarejustforyourconvenienceandtheyarenotintendedtotestthewebserviceversioningmechanismperse.Theseclientsare:

cdch14\WebServiceVersioning\Client20061231.html

and

cdch14\WebServiceVersioning\Client20070101.html

WebServiceVersioningOperationalPerspectiveAttheoperationsperspective,wecanusetoolstoedittheWSDLstoreflectthischangeandthenplacealltheWSDLsinarepositoryfortheconsumerstofindorevensupplytheseWSDLstotheconsumers.TheconsumerscanthenusetheirconventionaltoolstogenerateclientstubsandsendSOAPrequeststoaccesstheservice.Theversionaspectisnotrevealedtotheclients,insteadtheyarelimitedtotheWSDLs.

AsweareusinganESBasthemiddlewaremessaginginfrastructure,anotheroptionisthattheWSDLscanberetrievedfromtheiroriginalsource(forexample,http://localhost:8080/AxisEndToEnd20061231

/services/HelloWebService20061231?WSDL)ondemandbasisfromtheclient.Moreover,doanXSLtransformtoreplacethedifferentendpointaddresseswithasingle

covenantaddressandsupplythem.

SummaryWhiletheneedtoversionaserviceisstilltobedebated,oneaspectwhichweallneedtoacceptisthatservicesneedtobemaintainedinmultiplevariantstosatisfymultipleclassesofconsumers.Servicerequestcanbeenhancedtoincludeadditionalinformationwhichwillhelpproviderstoapplyrulestorouterequeststotheappropriateclassorvariantoftheservice.Whileitistrickytohandlethiskindofroutingusingatrivialhandlerorinterceptor-level,anESBprovidesyoualltherequireddesignpatternsandhookstoenforcecontent-basedrouting.Thenneithertheserviceprovidernortheserviceconsumerneedstobeawareofthesecomplexities.ThesedesignpatternsandhooksaregroupedunderthebroaderheadingofEIPandthenextchapterisgoingtolookatthemingreaterdepth,againwithworkingcodesamples.

Chapter15.EnterpriseIntegrationPatternsinESBBynowyouwillappreciatethefactthatintegrationisnotsimple.Now,howcanyoumakeitmanageableand/orrepeatableandthussimplifyintegration?Haven'tyoucomeacrossthesameproblemintraditionalsoftwareengineeringbefore?Howdidyoumanagetheproblemthen?Yes,IamreferringtonothingelseotherthanPatterns.

Inthischapter,wearegoingtocoverthefollowing:

EAIpatternsingeneral

EAIpatternsinServiceMix

WorkingcodedemonstratingEAIpatterns

EnterpriseIntegrationPatternsEnterpriseintegrationhastobemadesimpler.WeneedtoapplybestpracticestestedandproveninthetraditionalsoftwareengineeringparadigmslikeOOPtoenterpriseintegrationscenariosalso.ReusabilityisaprimeconcerninallITdesignrelateddecisionsandthisreusabilityhastohappenatmultiplelevelsincludingarchitecture,design,

implementation,andtesting.Whilewearchitectordesignforintegrationproblems,onewayofreusingtheexistingartifactsistoabstractoutthecommonmethodsusedforsolutionsandapplythemagainandagainforrecurring,similarproblems—wecallthisEIP.Letusdelvemoreintothis.

WhatareEAIPatterns?Eventhoughwedoenterpriseintegrationdailyknowinglyorunknowingly,ittakessomeexperienceandaholisticapproachtoseparateouttheintegrationaspectsfromtheroutineapplicationdevelopmentaspectsinasystemsenvironment.Whenweunderstandthisdifference,wehavetakenthefirststepinrecognizingEAIasaseparatestream,infactaspecializedstreamwhichrequiresspecificskillsetstolookatsystemsandservicesfromanintegrationpointofview.

Wewillstartthinkingintermsofconnectors,brokers,ormessagerouterswhichhaveaveryspecificroleandresponsibilityintheintegrationdomain.Theseareintegrationblockswhichwhencombinedtogetherindifferentwayswillgiveoutnewstylesorpatternsofmessageexchange.Hence,EAIpatternsarenuggetsofadvicemadeoutofaggregatingbasicMEPelementstosolvefrequentlyrecurringintegrationproblems.ForeverypracticalpurposethesearesimilartodesignpatternsandwecanlookatEAIpatternsasdesignpatternsforsolvingintegrationproblems.

EAIPatternsBookandSiteInwritingachapterdiscussingEAIpatterns,IhavetoinvariablypointtothegreatbookonEAIpatternsbyGregorHohpeandBobbyWoolf.Infact,thisbookisacollectionofabout65patterns,allprovidingmeanstosolvethedaytodayintegrationproblems.Eachofthepatternsisdescribedusingthefollowingsubheadings:

Name

Icon

Context

Problem

Forces

Solution

Sketch

Results

Next

Sidebars

Examples

Thebeautyofthesepatternsisthattheysolvenotonlycommonintegrationproblemsbutalsoenabletheintegrationarchitecttocombinethemtogethertocreatedesigns.Usingthesetheycansolveproblemswhichtheyhadneverthoughtabout.

Equallyimportantistheinfluenceofthediagramsandnotationsintheintegrationpatterns.Thishelpsarchitectsanddesignerstoshareacommonvocabularyinintegration.TheEAIbookandtheassociatedsiteprovidenotationswhichhaveacertain"sketch"quality.ThenitisnotrequiredtoreadhundredsofpagesofamanuallikethatofUMLtounderstandanduse.However,duetotheobjective-orientednotations,itiseasytoconveytheessenceofthepatterntothereaderataquickglance.Forexample,letuslookintoafewnotationsgiveninthefollowing:

Letusnowlookintosimpledefinitionsforthepatternscorrespondingtothenotationsshownabove:

Aggregator:Anaggregatorisusedtocollectandstoreindividualmessagepartsuntilacompletesetofco-relatedmessagepartshasbeenreceived.Oncealltherelatedpartshavebeenreceived,theyareaggregatedtogethertoformasinglemessage.

Splitter:Asplittercansplitoutacompositemessageintoaseriesofindividualmessageparts.

WireTap:Awiretapcanconsumemessagesfromasingleinputchannelandpublishtheunmodifiedmessagetotwooutputchannels.

Havinggonethroughthesimpleexplanationfortheabovenotations,ifyounowlookatthenotationsperse,youwillappreciatehoweasyisittocorrelatethefunctionalitywithitsnotation.

ServiceMixEAIPatternsServiceMixandJBIareallaboutintegratingbusinessservices.LetusnowseewhatServiceMixhastoofferintermsoftheEAIpatterns.

WhyServiceMixforEAIPatterns?ServiceMixprovidestheservicemix-eipcomponentasastandardJBI-compliantcomponent.ThisprovidesimplementationsformanyofthepatternsdiscussedintheEAIpatternsbook.WhenIfirstreadtheEAIpatternsbook,Iwaswonderingwhetherwehaveallthesepatternstogetherinsomereusableform,otherthanjustpatternsanddiagrams.Butasweallagree,patternsarenuggetsofguidelineswhichwecanimplementinmanyways,usinganytechnologyorplatform.

Infact,ifwelookatmanyMOMforintegrationssuchasWebsphereMQ,MicrosoftBiztalk,TIBCO,Webmethods,andMicrosoftMQ,theyalreadyprovidemanyofthesepatternsattheframework-level.Perhaps,wedidn'tnoticethemaspatternsinthefirstgo,butsurelyasexperiencebuildsupwecannotmissarepeatedwayofaddressingaproblemofaparticularnature.

MonthsaftermyfirstreadingoftheEAIpatternsbookIstartedevaluatingafewoftheSOI-basedproducts,especiallyintheJavaworldincludingMuleandtheESBframework.ThebestpartoftheseframeworksisthatwehavemanyoftheEAIpatternsintheformofcode!Believeme,ifIweretohave

usedtheseintegrationframeworksafewyearsback,itwouldhavesavedmemanymanmonths!Today,Iamwonderinghowmuchcodeourteamhaswrittenpreviouslyforreceiving,selecting,storing,andthensequencing,andaggregatingmultiplepassengernamelists(PNL)messagesforamajorairline.Lookattheflowgiveninthefollowing:

Here,IusedEAIpatternblockstoconnectthemtogethertocreatemyowndesignformyPNLpartmergingproblem.Forthis,wenolongerwriteJavaor.NETcodetoparsemyentirePNLmessagepart,selectthem,andstorethemandfinallywhenallpartsarereached,toresequencethemtoformthefullPNL.Instead,astheseindividualproblemsarealreadyaddressedasEAIpatterncomponents,Ijustneedtoselecttherequiredblocks,configure,andconnectthemtogetherandroutemymessagethroughthat.Don'tyouthinkthatisasmartwayofdoingthings?

Icanunderstand,youmaynotagreeifyouarereadingabouttheEAIpatternsforthefirsttime.However,Icanguaranteethatonceyoufinishreadingthischapterandalsoacoupleofmorechaptersinthisbookwhichsolvessomeofthemajorheadachesintheindustry,youwillbeinabetterpositiontoappreciatetheimportanceofEAIpatternsinintegration.

Forexample,buildingaprotocolbridgetobringreliabilitytoawebservicechannelortoimplementawebserviceversioning

mechanism,younomorethinktraditionally.However,IneedtoremindyouthatEAI,EAIpatterns,andMOMaregreatenablersforSOAandSOI,butmaynotbethesolutionforeveryproblemathand.Inotherwords,noneofthesepatternsorframeworksisgoingtoreplacethejudiciousdecisionyouareobligedtotakeasadesigneroranarchitect,topickthebesttechnologyorframeworkstosolveyourproblems.

Hence,byanychanceifyoudecidethatMOMisthewaytogoandyouwanttouseServiceMixasyourESBmiddleware,youcanusemanyEAIpatternblocksavailablehere.TheServiceMixservicemix-eipcomponentisaroutingcontainerontowhichyoucandeployyourownEAIpatternsorcombinationofpatternstosolvecomplexroutingorMEPproblems.

Forexample,youmaysometimeswanttotransformanIn-OutMEPtoacombinationofIn-OnlyMEPoryoumaywanttorouteyourmessagesdestination.Parallellyyoualsowanttodeliveracopyofthemessagetoatracecomponentinbetween.Don'teverwritecodefortheseinServiceMix,insteadrouteyourmessagesthroughasuitableEAIpatternblockdeployedontoservicemix-eip.

ServiceMixEAIPatternsConfigurationWecanconfigureservicemix-eipeitherinaSUasastandardJBIcomponentorusingtheservicemix.xmlconfigurationfile.Thisisshowninthefollowinglist:

Configureservicemix-eipasastandardJBIcomponent:servicemix-eipsupportsthestandardXBean-baseddeployment.Forthis,thexbean.xmlfilewillhavethefollowingentry:

<beans

xmlns:eip="http://servicemix.apache.org/eip/1.0">

<!--configureyourEAIPatterncomponents

here-->

</beans>

Configureservicemix-eipusingtheservicemix.xmlfile:

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:test="http://test.eip.servicemix.esb.binildas.com">

<sm:container...>

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<eip:component>

<eip:endpoints>

<!--configureEAIPatterncomponentshere--

>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

EAIPatterns—CodeandRunSamplesinESBThemainEAIpatterncomponentssupportedbyServiceMixarelistedasfollows:

Content-basedrouter

Contentenricher

XPathsplitter

Messagefilter

Splitaggregator

Pipeline

Wiretap

Staticrecipientlist

Staticroutingslip

LetusnowconfigureEAIpatterncomponentsintheServiceMixandrunthesamples.Allthesamplesarearrangedinsubfoldersunderch15\.Makesurethatyoueditexamples.PROPERTIESandchangethepathstheretomatchyourdevelopmentenvironmenttobuildthesamples.

Content-basedRouterAcontent-basedrouterconsumesamessagefromonemessagechannel.Basedonasetofconditionsontheheadersorthebodycontentofthemessage,itrepublishesthemessageontoadifferentmessagechannel.

NOTATION

EXPLANATIONThemessagerouterinspectsthecontentsofthemessageandroutesthemessagetomultiplechannels.Whiledoingso,therouterwillnotalterthemessagecontents.Whileinspecting,theroutercanlookintoafieldinthemessagebodyorthemessageheader.Usually,aconditionoraruleisattachedtotherouterwhichwilltryamatchwiththefieldinthemessage.Hencethisrulematchinghookistobedesignedasextensibleandisthetargetofconstantmaintenancewhenwewanttoaddmorerulesorwhenwewanttoplug-inmorechannelsmatchingtherules.

ILLUSTRATIVEDESIGNLetusconsidertheAcmeCompanyprovidingthewebinterfacetoendcustomerstoplaceordersforbuyingthegadgetsonline.TheAcmeorderinggatewaycanprovideasinglechannelforalltheincomingmessagesduetomaintenanceandsecurityreasons.Nowweneedamechanismtosegregateoutordersfordifferentkindsofgadgets.Eachkindofgadgets(apparelsandelectricals,forexample)hasitsowninventorysystem.Henceweneedtoroutedifferentkindsoforderstotheirrespectiveinventorysystems.

Weplug-inacontent-basedrouterandattachmultiple

outgoingchannelstothisrouter.Therouterwilllookatthemessagecontentsandidentifythekindoforder.Basedonthat,itwillroutethemessagetotheirrespectiveoutgoingchannelsfromwheretherespectiveinventorysystemscanpickupthemessages.Thisisshowninthefollowingfigure:

SAMPLEUSECASEThesampleusecasehasasetofcomponentsasshowninthefollowingfigure:

Letusnowlookintotheindividualcomponentsindetailinthefollowinglist:

JMSclient:ThisisanormalexternalJMSclient,placingdifferentXMLmessagesontotheJMSconsumercomponentconfiguredwithintheESB.

JMSconsumer:Thisisaservicemix-jmslisteningonqueue"A".Anyincomingmessagestothisqueuewillberoutedtothenextcomponentinthe

flowchain,thecontent-basedrouter.

Content-basedrouter:Thecontent-basedrouterisaservicemix-eipcomponent.BasedonthecontentoftheXMLmessageitreceives,itwillroutethemessage,unaltered,toanyoneamongstthesetofReceivercomponentsconfigured.

Receiver:Thereceivercomponentisacustomtransformcomponent.AnymessageitreceiveswillbeloggedintotheconsoleandthenechoedbywritingbacktotheoutmessageoftheIn-Out.Theoutmessageisplacedintheoutqueue.

JMSprovider:Thisisaservicemix-jmslisteningonqueue"B".ThereceivercomponentwillplaceitsoutmessageontothisqueuefromwheretheJMSclientcanpickup(eventhoughinthissamplewedon'tpickupthemessages).

SAMPLECODEANDCONFIGURATIONWeconfigurethecontent-basedrouterintheservicemix.xmlfile,alongwithothercomponentsdescribedabove.Thisisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://cbr.eip.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml">

<beanid="propertyConfigurer"

class="org.springframework.beans.

factory.config.PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

</bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="test:router"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpointservice="test:MyProviderService"

endpoint="myProvider"role="provider"

soap="false"destinationStyle="queue"

jmsProviderDestinationName="queueB"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver1"

service="test:receiver1"

destinationService="test:MyProviderService">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>1</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver2"

service="test:receiver2"

destinationService="test:MyProviderService">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>2</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver3"

service="test:receiver3"

destinationService="test:MyProviderService">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>3</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver4"

service="test:receiver4"

destinationService="test:MyProviderService">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>4</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:content-based-routerservice="test:router"

endpoint="endpoint">

<eip:rules>

<eip:routing-rule>

<eip:predicate>

<eip:xpath-predicatexpath="number(hello@id)&lt;

2">

<eip:predicate>

<eip:target>

<eip:exchange-targetservice="test:receiver1">

<eip:target>

</eip:routing-rule>

<eip:routing-rule>

<eip:predicate>

<eip:xpath-predicatexpath="number(hello@id)=

2">

<eip:predicate>

<eip:target>

<eip:exchange-targetservice="test:receiver2">

<eip:target>

</eip:routing-rule>

<eip:routing-rule>

<eip:predicate>

<eip:xpath-predicatexpath="number(hello@id)&gt;

3">

<eip:predicate>

<eip:target>

<eip:exchange-targetservice="test:receiver4">

<eip:target>

</eip:routing-rule>

<eip:routing-rule>

<eip:target>

<eip:exchange-targetservice="test:receiver3">

<eip:target>

</eip:routing-rule>

</eip:rules>

</eip:content-based-router>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

ThecomponentsconfiguredintheaboveJBIconfigurationhavealreadybeenexplainedintheprevioussection.Weneedtodeclaretheeipnamespaceasxmlns:eip=http://servicemix.apache.org/eip

/1.0.Wewillalsousetheservicemix-jmscomponentforwhichwedeclaretheJMSnamespaceasxmlns:jms=http://servicemix.apache.org/jms

/1.0.

TheMyReceiverclassisshownasfollows:

publicclassMyReceiverextends

TransformComponentSupportimplements

MessageExchangeListener

{

privateStringname;

publicvoidsetName(Stringname){this.name=

name;}

publicStringgetName(){returnname;}

protectedbooleantransform(MessageExchange

exchange,NormalizedMessagein,NormalizedMessage

out)throwsMessagingException

{

NormalizedMessagecopyMessage=

NormalizedMessagecopyMessage=

exchange.createMessage();

getMessageTransformer().transform(exchange,in,

copyMessage);

Sourcecontent=copyMessage.getContent();

StringcontentString=null;

if(contentinstanceofDOMSource)

{

contentString=XMLUtil.node2XML(((DOMSource)

content).getNode());

}

if(contentinstanceofStreamSource)

{

contentString=

XMLUtil.formatStreamSource((StreamSource)

content);

}

System.out.println("MyReceiver.transform("+name

+").contentString="+contentString);

out.setContent(newStringSource(contentString));

returntrue;

}

}

TheMyReceiverclassprintsoutthemessageandechoesthesamemessageback.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\01_ContentBasedRouterandtypethefollowing:

ant

Thiswillcompileallthefiles,includingtheJMSclient

program.Nowtotestthesample,firstbringServiceMixupbyexecutingthefollowingcommands:

cdch15\01_ContentBasedRouter

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrun,asshownhere:

cdch15\01_ContentBasedRouter

antrun

TheJMSclientprogramconsolewillprintoutthemessagesitsendstotheESB.Thisisshowninthefollowingscreenshot:

Now,havealookatthecontent-basedrouter.Asshowninthecontent-basedrouterconfiguration,wehavethecontent-basedrouterrulesembeddedastheXPathpredicates.Basedonthematchinthemessagecontent,therouterwillroutethemessagetotheirrespectivedestinations(Receiver1or2or3

or4).TheESB-sideconsoleprintoutvalidatesthisasshowninthefollowingscreenshot:

ContentEnricherThecontentenrichersupplementstheoriginalmessagewithmorerelatedinformationretrievedfromtheothersources.Theoriginalmessagewillbealteredtocontainenrichedinformation.

NOTATION

EXPLANATIONSometimesamessagemaynotcontainalltherequiredinformationforthenextprocessingsteptoactorthenext

processingrequiredmoreadditionalinformationtobeappendedtotheincomingmessage.Insuchscenarios,thecontentenrichercanappendtheadditionalinformationtotheoriginalmessageandthensendtothenextlinkintheprocessingchain.

ILLUSTRATIVEDESIGNTheAcmeonlinecustomersatthetimeofcheckoutwillentercreditcarddetails.TheAcmebackendwouldneedtodocreditauthorization.However,thedataenteredbythewebpagecustomersmightbeminimalandfortheactualauthorizationwemightneedtoaddmoredetailssuchasSSN,beforetherequestisroutedtoCreditCheckService.AContentEnrichercangetthecustomeridentificationdata(customerkey)fromtheincomingmessageandretrievetheextradetailsfromalocalresourcestore.Theextradetailscannowbeappendedtotheoriginalmessageandthenroutedtothetargetservice.Thewholesetupisshowninthefollowingfigure:

SAMPLEUSECASE

ThefollowingfigureillustrateshowvariouscomponentscanbeassembledintheJBIbusforoursampleusecase:

Thesampleusecasewillhavefollowingcomponents:

JMSclient:ThisisanormalexternalJMSclient,placingXMLmessagesontotheJMSConsumercomponentconfiguredwithintheESB.

JMSconsumer:Thisisaservicemix-jmslisteningonqueue"A".AnyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichistheContentEnricher.

Contentenricher:TheContentEnricherrouterisaservicemix-eipcomponent.Itenrichestheoriginalmessagewithadditionalinformation.TheenrichedmessagewillbeplacedbackintheJMSProviderqueue.

Contentappender:TheContentAppenderisacustomtransformcomponent.ItprovidesaresultElementwithnametest:kerberosticketsothatthecontentenrichercanenrichtheoriginalmessagewiththisadditionalresultElement.

JMSprovider:Thisisaservicemix-jmslisteningonqueue"B".TheContentEnrichercomponentwillplaceitsoutmessageintothisqueuefromwheretheJMSClientcanpickup.

SAMPLECODEANDCONFIGURATIONWeconfigurethecontentenricherintheservicemix.xmlfile,alongwithothercomponentsdescribedabove.Thecontentofthisfileisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://cer.eip.servicemix.esb.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.

factory.config.PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"

targetService="test:contentEnricher"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpointservice="test:MyProviderService"

endpoint="myProvider"role="provider"

soap="false"destinationStyle="queue"

jmsProviderDestinationName="queueB"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:content-enricher

service="test:contentEnricher"

endpoint="endpoint"

enricherElementName="test:subject"

requestElementName="test:principal"

resultElementName="test:credential">

<eip:enricherTarget>

<eip:exchange-target

service="test:contentAppender">

<eip:enricherTarget>

<eip:target>

<eip:exchange-target

service="test:MyProviderService">

<eip:target>

</eip:content-enricher>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpec

componentName="contentAppender"

service="test:contentAppender">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="ContentAppender">

<constructor-argref="jbi">

<bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

WhenweconfigurethecontentenricherwecanspecifytheenricherElementName,requestElementName,andtheresultElementName.Theoutputofthecontentenricherwillbewrappedwithintheseelementsasseeninthesampleoutputinthefollowingscreenshot.LetusalsolookattheContentAppenderJavaclass:

publicclassContentAppenderextends

ComponentSupportimplements

MessageExchangeListener{

privateJBIContainercontainer;

publicContentAppender(JBIContainercontainer)

{

this.container=container;

}

}

publicvoidonMessageExchange(MessageExchange

exchange)

throwsMessagingException

{

if(exchange.getStatus()==

ExchangeStatus.ACTIVE)

{

booleantxSync=exchange.isTransacted()&&

Boolean.TRUE.

equals(exchange.getProperty(JbiConstants.SEND_SYNC));

NormalizedMessageout=exchange.createMessage();

out.setContent(newStringSource("<?xml

version='1.0'encoding='UTF-8'?>

<test:kerberosticketxmlns:test=

\"http://xslt.servicemix.apache.binildas.com\">

123456789</test:kerberosticket>"));

exchange.setMessage(out,"out");

if(txSync)

{

sendSync(exchange);

}

else

{

send(exchange);

}

}

}

}

Here,wewritetheinformationtoenrichtheoriginalmessagetotheout.Inactualscenarios,wemaywanttoretrievesomekeyfromtheincomingmessage,retrievemoredatafromalocalresourceusingthiskeyandgeneratetheadditionalinformation.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\02_ContentEnricherandtypeant.Thisisshownasfollows:

cdch15\02_ContentEnricher

ant

Thiswillcompileallthefiles,includingtheJMSclientprogram.Nowtotestthesample,first,bringtheServiceMixupbyexecutingthefollowing:

cdch15\02_ContentEnricher

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrun.

cdch15\02_ContentEnricher

antrun

TheJMSclientprogramconsolewillprintoutthemessagesitsendstotheESB.Italsoprintsouttheresponsemessagefromthecontentenricher.TheJMSclientconsoleisshowninthefollowingscreenshot:

XPathSplitterAnXPathsplitterisbasedontheoriginalsplitterEAIpattern.Asplittercanidentifyrepeatingelementsinamessageandsplitthemessageandpublisheachelementpartasseparatemessagestoadifferentchannel.Thesplittercanalsoseparateoutnon-repeatingelements,insuchcasethepublishedmessagewillbeasubsetoftheoriginalmessage.XPathsplitterusesXPathtofindtherepeatingelementpattern.

NOTATION

EXPLANATION

Manycompositedocumentslikeafullairlinepassengernamelistoranorderwithmanyorderitemswillcontainrepeatingelements.Sometimeswemayneedtoprocesseachoftheserepeatingelementsseparately.AnXPathsplittercansplitthecompositemessageintoindividualpartsbasedontherepeatpatternandpublishesthepartsontodifferentdestinations.

ILLUSTRATIVEDESIGNUsingtheAcme'sonlinee-commercepages,acustomercanaddmultipleitemstotheshoppingcartandattheendoftheshoppingtriphecancheckout.Thiswillsubmitasingleorderinthebackend,buttheordercancontainmultipleorderitems.Now,foreachorderitem,weneedtodoaseparateinventorycheck.Tosolvethisproblem,wecanroutetheordertoanXPathsplitterfirst.Thesplittercansplittheorderintoindividualorderitemsandeachorderitemcanbepushedtothequeueasaseparatemessage.Nowitiseasytoplug-inacontent-basedrouteraswehavediscussedalready.Theneachnewmessageencapsulatingoneorderitemcanberoutedtotheirrespectiveinventoryqueues.

SAMPLEUSECASEThesampleusecasewillhavethefollowingcomponents:

JMSclient:ThisisanormalexternalJMSclient,placingtheXMLcompositemessagesontotheJMSconsumercomponentconfiguredwithintheESB.

JMSconsumer:Thisisaservicemix-jmslisteningonqueue"A".AnyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichistheXPathsplitter.

XPathsplitter:TheXPathsplitterisaservicemix-eipcomponent.Onreceivingtheinmessages,thesplitterwilltrytomatchtheXPathconfiguredatthesplitter-levelwiththemessagecontent.Infindingamatch,thesplitterwillsplittheoriginalmessageintoasmanypartsastherearerepeatingelementsaspertheXPath.Eachoftheseindividualelementsisrepublishedasaseparatemessagetotheexchange-targetwhichisatracecomponent.

Tracecomponent:Thetracecomponentjustspitsoutwhatevermessageitreceivesintotheconsole.

Thefollowingfigureillustrateshowthevariouscomponents

canbeassembledintheJBIbusforoursampleusecase:

SAMPLECODEANDCONFIGURATIONWeconfiguretheXPathsplitterinservicemix.xml,alongwithothercomponentsdescribedabove:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="test:xpathSplitter"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:xpath-splitterservice="test:xpathSplitter"

endpoint="xpathSplitterEndpoint"xpath="hello*">

<eip:target>

<eip:exchange-targetservice="my:trace">

<eip:target>

</eip:xpath-splitter>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="trace"

service="my:trace">

<sm:component>

<beanclass="org.apache.servicemix.components.

util.TraceComponent">

<sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

TheXPathweconfiguredhereishello*.Thiswillspliteachelementinsidethehelloelementintoindividualmessages.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\03_XPathSplitterandtypeantasgivenhere:

cdch15\03_XPathSplitter

ant

Thiswillcompileallthefiles,includingtheJMSclient

program.Nowtotestthesample,firstbringServiceMixupbyexecutingthefollowingcommands:

cdch15\03_XPathSplitter

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrunasshownhere:

cdch15\03_XPathSplitter

antrun

TheJMSclientprogramconsolewillprintoutthemessagesitsendstotheESBasshowninthefollowingscreenshot:

NowontheESB-side,thefirstmessagewillbesplitintothreepartswhereasthelast(third)messagewillbesplitintotwoparts.

INFO-TraceComponent

-Bodyis:<?xmlversion="1.0"

encoding="UTF-8"?><one/>

INFO-TraceComponent

-Bodyis:<?xmlversion="1.0"

encoding="UTF-8"?><three/>

INFO-TraceComponent

-Bodyis:<?xmlversion="1.0"

encoding="UTF-8"?><two/>

INFO-TraceComponent

-Bodyis:<?xmlversion="1.0"

encoding="UTF-8"?><five/>

INFO-TraceComponent

-Bodyis:<?xmlversion="1.0"

encoding="UTF-8"?><four/>

StaticRecipientListArecipientlistcaninspectanincomingmessage,anddependinguponthenumberofrecipientsspecifiedintherecipientlist,itcanforwardthemessagetoallchannelsassociatedwiththerecipientsintherecipientlist.

NOTATION

EXPLANATIONTheexampleforascenariowhereweneedtosendthesamemessagetomultiplerecipientsistheemailmessage.Witheveryemailmessage,thesendercanspecifymultiple

recipientsintheTo,Cc,orBccfields.Now,theemailsystemcaninspectthesefieldsandifmorethanonerecipientisspecifiedintheselists,itwillforwardthesamemessagetoalltherecipientaddressesspecified.

ILLUSTRATIVEDESIGNWhenevertheAcmeback-endsystemreceivesaconfirmedorder,thesamehastobedistributedtobothpackingsystemsandshippingsystems,alongwiththeinventorysystemswhichwehavealreadydiscussed.Wecanconfigureastaticrecipientlistspecifyingashippingqueue,apackingqueue,andathirdqueueforacontent-basedrouterforinventorysystemsasshowninthefollowingfigure.TheadvantageisthatalltheseLOBsystemswillreceivethesameordersothattheycaninitiatetheirassociatedbusinessprocesses.Thisisillustratedinthefollowingfigure:

SAMPLEUSECASEThesampleusecasewillhavefollowingcomponents:

JMSclient:ThisisanormalexternalJMSclient,placingXMLcompositemessagesontotheJMSconsumercomponentconfiguredwithintheESB.

JMSconsumer:Thisisaservicemix-jmslisteningonqueue"A"'.AnyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichistheStaticRecipientList.

Staticrecipientlist:TheStaticRecipientListisaservicemix-eipcomponent.Onreceivinginmessages,theStaticRecipientListwillforwardthemessagetoallrecipients,whicharedifferentinstancesofreceivercomponents,configuredintheStaticRecipientList.

Receivercomponent:Thereceivercomponentjustspitsoutwhatevermessageitreceivesintotheconsole.

ThefollowingfigureillustrateshowthevariouscomponentscanbeassembledintheJBIbusforoursampleusecase:

SAMPLECODEANDCONFIGURATIONWeconfiguretheStaticRecipientListinservicemix.xml,alongwiththeothercomponentsdescribedabove.Theservicemix.xmlfileisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="test:recipients"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:static-recipient-list

service="test:recipients"endpoint="endpoint">

<eip:recipients>

<eip:exchange-targetservice="test:receiver1">

<eip:exchange-targetservice="test:receiver2">

<eip:exchange-targetservice="test:receiver3">

<eip:recipients>

</eip:static-recipient-list>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver1"

service="test:receiver1">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>1</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver2"

service="test:receiver2">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>2</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver3"

service="test:receiver3">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>3</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

Wehaveconfiguredthreerecipientsnamelytest:receiver1,test:receiver2,andtest:receiver3inthestaticrecipientlistabove.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\04_StaticRecipientListandtypeantasshownhere:

cdch15\04_StaticRecipientList

ant

Thiswillcompileallthefiles,includingtheJMSclientprogram.Nowtotestthesample,first,bringServiceMixupbyexecutingthefollowingcommands:

cdch15\04_StaticRecipientList

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrun.

cdch15\04_StaticRecipientList

antrun

TheJMSclientprogramconsolewillprintoutthemessagesitsendstotheESBasshowninthefollowingscreenshot:

Atthesametime,ifyouobservetheESBconsole,youcanseethemessageisdeliveredtoallthethreerecipientsintherecipientlist.

Wiretap

Thewiretapisakindofsimplerecipientlistwhich,wheninsertedintothemessagechannel,willpublisheachincomingmessageintothemainchannelaswellasintoasecondarychannel.

NOTATION

EXPLANATIONThewiretapisastaticrecipientlist,withonlytworecipientsinthelist.Wheninsertedintothemainchannel,itpublishestheinputmessageintothemainchannelaswellasthesecondarychannelconfiguredinthewiretap.Thewiretapwillnotmodifythemessagecontentsinanymanner.

ILLUSTRATIVEDESIGNSupposeyouwanttodoanauditforeverycreditcardpaymentthatyoumakethroughyourAcmeonlinestore.Yourcreditcardinformationwillreachtheback-endsystemandtherewecanuseawiretap.Hencethismessageisalsopublishedintoasecondaryauditmodulewhichwillwriteallrequiredinformationtoanon-erasabledisk.

SAMPLEUSECASEThesampleusecasewillhavethefollowingcomponents:

HTTPclient:ThisisanexternalHTTPclient,placingtheXMLmessagesontotheHTTPconnectorcomponentconfiguredwithintheESB.

HTTPconnector:ThisisaServiceMixHTTPcomponentlisteningonport8912.Anyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichisthewiretap.

Wiretap:Thewiretapisaservicemix-eipcomponent.Onreceivinginmessages,thewiretapwillforwardthemessagetothemaintarget(anEchocomponentinourcase)aswellastothelistener(aTracecomponenthere).WiretapcanhandleallfourstandardMEPs,butcanonlysendanIn-OnlyMEPtothelistener.

Echocomponent:TheechocomponentisthemaintargetofthewiretapandwilltakepartinanIn-OutMEPintheflow.Hencetherequestisechoedbacktothewiretapandthentotheconsumercomponentofthewiretap(HTTPconnector).

Tracecomponent:TheTracecomponenttakespartinanIn-OnlyMEPintheflowandwillprintthemessageintheconsole.

ThefollowingfigureillustrateshowthevariouscomponentscanbeassembledintheJBIbusforoursampleusecase:

SAMPLECODEANDCONFIGURATIONWeconfigurethewiretapintheservicemix.xmlfile,alongwithothercomponentsdescribedabove.Thisfileisreproducedinthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.

config.PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpeccomponentName="httpReceiver"

service="test:httpBinding"

endpoint="httpReceiver"

destinationService="test:wireTap">

<sm:component>

<beanclass="org.apache.servicemix.

components.http.HttpConnector">

<propertyname="host"value="localhost"/>

<propertyname="port"value="8912">

<bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="echo"

service="test:echo">

<sm:component>

<beanclass="org.apache.servicemix.

components.util.EchoComponent">

<sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="trace"

service="test:trace">

<sm:component>

<beanclass="org.apache.servicemix.components.

util.TraceComponent">

<sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:wiretapservice="test:wireTap"

endpoint="wireTapEndpoint">

<eip:target>

<eip:exchange-targetservice="test:echo">

<eip:target>

<eip:inListener>

<eip:exchange-targetservice="test:trace">

<eip:inListener>

</eip:wiretap>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

Wehaveconfiguredbothtest:echoandtest:traceasthelistenersforthemessageexchangeinthewiretap.Hencethemessagewillbeforwardedtoboththesecomponents.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\05_WireTapandtypeant:

cdch15\05_WireTap

ant

Thiswillcompileallthefiles,includingtheHTTPclient

program.Nowtotestthesample,firstbringServiceMixupbyexecuting:

cdch15\05_WireTap

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrun.

cdch15\05_WireTap

antrun

TheHTTPclientprogramwillsendthetestXMLmessagetotheHTTPconnectorconfiguredintheESB.IntheESBconsolewecanvalidatethatthemessageisdeliveredtoboththetest:echoandtest:traceservices.TheHTTPclientalsoprintsouttheresponsereceivedbackfromtheESB.

MessageFilterMessagefiltercaneliminatetheunwantedmessagesfromasetofmessagespublished.

NOTATION

EXPLANATION

Messagesareofdifferentkinds,andthesameistruewitheventsalso.Thereareunwantedeventsandeventswhicharetobetrackedandreactedbasedoneventtypeinparticularfashions.Whetheramessageisofinterestornotisagainbasedonthemessagecontent.Hencethemessageswhichmatchthefilterruleofinterestneedtoberoutedfurtherwhereasthemessageswhichdidn'tmatchthefiltercriterionareignored.Allthemessageswhichmatchthecriterionwillberoutedtotheoutputchannelofthemessagefilter.

ILLUSTRATIVEDESIGNAcmehasdecidedtoofferdiscountsandgiftsforallpurchasesexceedingacertainamountinasinglecheckout.Toprocessthis,wecanfirstuseawiretaptosendacopyofallorderstoamessagefilter.Themessagefilterwillinspectthemessageforthetotaldollarvalueofcheckoutandifitexceedsthethreshold,themessagewillbeforwardedtotheoffermanagementmodule.Anyordermessageswithtotaldollarvaluelessthanthethresholdwillbeignored(dropped)atthemessagefilter,notforwardingthemtotheoffermanagementmodule.Notethat,wearedirectingcopiesofordersonlytothemessagefilterhencealltheoriginalmessageswillberoutedtotheirrespectiveinventorymodules,irrespectiveofwhethertheircopiesareforwardedordroppedatthemessagefilter.Thisisillustratedinthefollowingfigure:

SAMPLEUSECASEThesampleusecasewillhavefollowingcomponents:

JMSclient:ThisisanormalexternalJMSclient,placingXMLmessagesontotheJMSconsumercomponentconfiguredwithintheESB.

JMSconsumer:Thisisaservicemix-jmslisteningonqueue"A".AnyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichistheMessageFilter.

Messagefilter:TheMessageFilterisaservicemix-eipcomponent.Onreceivingtheinmessages,thefilterwilltrytomatchthefilterruleconfiguredatthefilter-levelwiththemessagecontent.Inthesample,weusetheXPathpredicatetodefinethefilterrule.Infindingamatch,thefilterwillforwardthemessagetotheexchange-targetwhichisareceivercomponent.Anymessagewhichdoesn'tmatchwillbedroppedatthefilter-level.

Receivercomponent:Thereceivercomponentjustspitsoutwhatevermessageitreceivesintotheconsole.

ThefollowingfigureillustrateshowthevariouscomponentscanbeassembledintheJBIbusforoursampleusecase:

SAMPLECODEANDCONFIGURATIONWeconfiguretheMessageFilterintheservicemix.xmlfile,alongwithothercomponentsdescribedabove.Thisisshowninthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="test:messageFilter"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver"

service="test:receiver">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>1</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:message-filterservice="test:messageFilter"

endpoint="messageFilterEndpoint">

<eip:target>

<eip:exchange-targetservice="test:receiver">

<eip:target>

<eip:filter>

<eip:xpath-predicate

xpath="hello@id='1'">

<eip:filter>

</eip:message-filter>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

ThefilterrulewearespecifyinghereistheXPath"hello@id='1'".ThecodeforMyReceiver.javaclassisverysimilartotheMyReceiverusedinthecontent-basedroutersample.Theonlydifferenceisthatitwon'twriteanycontentbacktotheout.Hencewearenotrepeatingthecodehere.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\06_MessageFilterandtypeantasshownhere:

cdch15\06_MessageFilter

ant

Thiswillcompileallthefiles,includingtheJMSclientprogram.Nowtotestthesample,first,bringServiceMixupbyexecuting:

cdch15\06_MessageFilter

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrun.

cdch15\06_MessageFilter

antrun

TheJMSclientprogramconsolewillprintoutthemessagesitsendstotheESBasshowninthefollowingfigure:

IfwelookattheESBconsole,wecanseethatonlytwoofthemessagesarefilteredandforwardedtothereceivercomponentandtheothertwomessagesaredropped.

SplitAggregatorAnaggregatorisakindofstatefulfilterwhichcanstoremessagepartswhicharecorrelatedbysomeformofIDorfield.Whenallthepartsarereadyitcanaggregatealltheparts

andpublishasingleaggregatemessage.

NOTATION

EXPLANATIONInmanycasesmessagepartswhichareco-relatedarriveatdifferenttimesandwecannotproceedfurtherprocessingunlesswereceivethemessageinfull.Thescenarioiscommonintheairlinedomainwherethemessagingchannelsplitsandsendspassengerreservationlistsandpassengernamelistsinparts,duetosizelimitationsimposedbyEDImessaginggateways.Theprocessingmodulehastowaituntilitreceivesallthepartsofaco-relatedmessage.Tohelpthecorrectorderingofmessagesbackandtoidentifywhetherwehavereceivedallpartsofthemessage,theaggregatordependsonseveralpropertiessuchascount,index,andcorrelationID.Eachintermittentresultisstoredbytheaggregatoruntilthemessageisfullyaggregated.Hencetheaggregatorisstatefulinnature.

ILLUSTRATIVEDESIGNEveryfullorderintheAcmeback-endsystemhastobevalidatedwithanavailablestockbeforewecanconfirmtheorder.Wealreadydiscussedthatwesplittheorderintoorderitemsandsendindividualmessagescorrespondingtoeach

itemtodifferentinventorymodules.Now,beforewecanreturnbacktheordervalidationmessagetothecustomerweneedtoexaminethevalidationstatusofeachorderitemfromtheinventorymodules.Onepossibleconfigurationistouseanaggregatortowhichalltheinventorymodulescanroutetheindividualorderitemstatusmessages.Theaggregator,whenitreceivesthestatusmessagesfromalltherelatedorderitems,canevaluatetheoverallstatusandsendbackthedecision(confirmedorderorerror).Thisisshowninthefollowingfigure:

SAMPLEUSECASEThesampleusecasewillhavethefollowingcomponents:

DefaultServiceMixclient:ThedefaultServiceMixclientwillsendseveralIn-OnlymessagestothesplitaggregatorconfiguredintheESB.Eachofthesemessagesiscorrelated,andtheyalsocarrythesplitCountandsplitIndexalongwiththeirmessageproperties.

Splitaggregator:Thesplitaggregatorisaservicemix-eipcomponent.

Onreceivingtheinmessages,theaggregatorwilllookatthecorrelationID,splitCount,andsplitIndexandcanrearrangeandaggregatethemessagesirrespectiveoftheorderinwhichthemessagesarrive.Wheneverypartofamessagehasarrived,thefullyaggregatedmessageisforwardedtothenextcomponentintheflowchainwhichisthetracecomponent.

Tracecomponent:ThetracecomponentprintsouttheaggregatedmessagesreceivedfromthesplitaggregatortotheESBconsole.

ThefollowingfigureillustrateshowthevariouscomponentscanbeassembledintheJBIbusforoursampleusecase:

SAMPLECODEANDCONFIGURATIONWeconfiguretheSplitAggregatorintheservicemix.xml

file,alongwithothercomponentsdescribedabove.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containerid="jbi"

monitorInstallationDirectory="false"

createMBeanServer="false"useMBeanServer="false">

<sm:activationSpecs>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:split-aggregatorservice="test:aggregator"

endpoint="aggregatorEndpoint"

aggregateElementName="test:MessageEnvelope"

messageElementName="test:MessagePart">

<eip:target>

<eip:exchange-targetservice="test:trace">

<eip:target>

</eip:split-aggregator>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="trace"

service="test:trace">

<sm:component>

<beanclass="org.apache.servicemix.components.

util.TraceComponent">

<sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="client"

class="org.apache.servicemix.client.

DefaultServiceMixClient">

<constructor-argref="jbi">

<bean>

</beans>

ThesplitaggregatorisconfiguredwiththeelementsaggregateElementNameandmessageElementName.Thesetwoelementswilldecidethemessageenvelopestobeusedwhenthesplitaggregatoraggregatesthemessage.

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\07_SplitAggregatorandtypeantasshownhere:

cdch15\07_SplitAggregator

ant

Thiswillcompileallthefiles.Nowtotestthesample,justexecutetheruntargetofbuild.xmlasshownasfollows:

cdch15\07_SplitAggregator

antrun

ObservetheESBconsole;youcanseethemessagesbeingsentouttotheaggregatorandfinallytheaggregatorcombinesallrelatedmessagesandforwardsthemtothetracecomponentwhichwillprintoutthemessagetotheconsole.Thisisshownasfollows:

Sendmsg:corrId<1178104210727>:

splitterCount<3>:splitterIndex<1>:msg<<hello

id="1"><binil/><sowmya/></hello>>

Waiting5000millisbeforenextmessage...

Sendmsg:corrId<1178104215726>:

splitterCount<2>:splitterIndex<1>:msg<<hello

id="1"><ann/></hello>>

Waiting5000millisbeforenextmessage...

Sendmsg:corrId<1178104210727>:

splitterCount<3>:splitterIndex<0>:msg<<hello

id="0"><binil/><sowmya/></hello>>

Waiting5000millisbeforenextmessage...

Sendmsg:corrId<1178104215726>:

splitterCount<2>:splitterIndex<0>:msg<<hello

id="0"><ann/></hello>>

Waiting5000millisbeforenextmessage...

INFO-TraceComponent-Exchange:InOnly[

id:ID:10.10.10.10-1124c7badc9-2:0

status:Active

role:provider

service:

{http://xslt.servicemix.apache.binildas.com}trace

endpoint:trace

in:<?xmlversion="1.0"encoding="UTF-8"?>

<test:MessageEnvelope

<test:MessageEnvelope

xmlns:test="http://xslt.servicemix.apache.binildas.com"

count="2"><test:MessagePartindex="0"><hello

id="0"><ann/></hello></test:MessagePart>

<test:MessagePartindex="1"><helloid="1"><ann/>

</hello></test:MessagePart>

</test:MessageEnvelope>

]receivedINmessage:

org.apache.servicemix.jbi.messaging.NormalizedMessageImpl@199197b{properties:

{org.apache.servicemix.eip.splitter.corrid=1178104215726}}

INFO-TraceComponent-Bodyis:<?xml

version="1.0"

encoding="UTF-8"?><test:MessageEnvelope

xmlns:test="http://xslt.servicemix.apache.binildas.com"

count="2"><test:MessagePartindex="0"><hello

id="0"><ann/></hello></test:MessagePart>

<test:MessagePartindex="1"><helloid="1"><ann/>

</hello></test:MessagePart>

</test:MessageEnvelope>

Sendmsg:corrId<1178104210727>:

splitterCount<3>:splitterIndex<2>:msg<<hello

id="2"><binil/><sowmya/></hello>>

Waiting5000millisbeforenextmessage...

INFO-TraceComponent-Exchange:InOnly[

id:ID:10.10.10.10-1124c7badc9-2:1

status:Active

role:provider

service:

{http://xslt.servicemix.apache.binildas.com}trace

endpoint:trace

in:<?xmlversion="1.0"encoding="UTF-8"?>

<test:MessageEnvelope

xmlns:test="http://xslt.servicemix.apache.binildas.com"

count="3"><test:MessagePartindex="0"><hello

id="0"><binil/><sowmya/></hello>

</test:MessagePart><test:MessagePartindex="1">

<helloid="1"><binil/><sowmya/></hello>

</test:MessagePart><test:MessagePartindex="2">

<helloid="2"><binil/><sowmya/></hello>

</test:MessagePart></test:MessageEnvelope>

]receivedINmessage:

org.apache.servicemix.jbi.messaging.NormalizedMessageImpl@195ff24{properties:

{org.apache.servicemix.eip.splitter.corrid=1178104210727}}

INFO-TraceComponent-Bodyis:<?xml

version="1.0"encoding="UTF-8"?>

<test:MessageEnvelope

xmlns:test="http://xslt.servicemix.apache.binildas.com"

count="3"><test:MessagePartindex="0"><hello

id="0"><binil/><sowmya/></hello>

</test:MessagePart><test:MessagePartindex="1">

<helloid="1"><binil/><sowmya/></hello>

</test:MessagePart><test:MessagePartindex="2">

<helloid="2"><binil/><sowmya/></hello>

</test:MessagePart></test:MessageEnvelope>

PipelineAPipelineisakindofbridgewhichcantransformoneformofMEPtoanother.

NOTATION

Forapipeline,thereisnonotationprovidedintheEAIpatternscollection.HencethebridgeEAIpatternisextendedandshownhere.Themotivationbehinddoingsoisthatitispossibletobuildabridgebetweentwomessageexchangepatternsusingapipeline.

EXPLANATIONApipelinecanbeconfiguredtotransformanIn-OnlyMEPtoanIn-Out.Thatis,whenthepipelinereceivesanIn-OnlyMEP,itsendsthemessageinanIn-OutMEPtothetransformercomponent.Hence,thetransformerwillsendaresponseasanoutmessagefortheIn-Out.ThisoutmessageisthenforwardedtothepipelinetargetinanotherIn-OnlyMEP.

UsingtheMEPtransformationpropertyofpipeline,itispossibletoconstructaprotocolbridge.Forexample,wecanbridgebetweenaHTTPprotocol(In-Out)andaJMS(In-Only)protocol.ThisiswhatwehavedoneinChapter11(AccessWebServicesusingJMSChannel).

ILLUSTRATIVEDESIGNTheAcmee-commercesystemallowscustomersonlinetomakepaymentsandeachsuchpaymentmessageisroutedtothefinancialinstitution'ssysteminasecureandreliablemanner.ThefinancialinstitutionisAcme'spaymentpartnerandtheirsystemsareseparatedinadifferentnetworkanddomain.SendingrequeststhroughInternetisafeasiblemethod,buttheusualHTTPchanneldoesnothavetherequiredreliability.HencethereisadedicatednetworkbetweenAcmeandthefinancialinstitution.Moreover,tomakemessagingreliableitispossibletosendmessagesusingareliablechannelthroughMOM.UsingJMS,wecansendmessagesthroughMOM.However,thepaymentserviceatthefinancialinstitution'sendisaHTTPservicewitharequest-replystyle.HencetheIn-OnlyMEPusedinJMSdoesn'tfit

well.Apipelinecansolvethisproblembyprovidingabridgebetweenthetwoprotocols—JMSandHTTP.Thisdesignisshowninthefollowingfigure:

YoumayalsorefertheChapter11(AccessWebServiceusingJMSChannel)toseeanimplementationforthis.

SAMPLEUSECASEThesampleusecasewillhavethefollowingcomponents:

JMSclient:ThisisanormalexternalJMSclient,placingXMLmessagesontotheJMSconsumercomponentconfiguredwithintheESB.

JMSconsumer:Thisisaservicemix-jmslisteningonqueue"A".Anyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichisthepipeline.

Pipeline:ThePipelineisaservicemix-eipcomponent.ThepipelinereceivesanIn-OnlyMEPfromJMSconsumer.ThepipelinethensendsthesamemessageinanIn-OutMEPtotheechocomponent.TheechoedresponseissendbacktothepipelinewhichisthenforwardedtotheJMSconsumerinanotherIn-OnlyMEP.

Echocomponent:Theechocomponentechoesbackanymessagesitreceives.Themessagereceivedfromthepipelineisthussentbacktothepipeline.

JMSprovider:Thisisaservicemix-jmslisteningonqueue"B".ThepipelinewillplacetheechoedbackmessageintothisqueueinanIn-OnlyMEPfromwheretheJMSclientcanpickup.

ThefollowingfigureillustrateshowthevariouscomponentscanbeassembledintheJBIbusforoursampleusecase:

SAMPLECODEANDCONFIGURATIONWeconfigurethepipelineintheservicemix.xmlfile,alongwithothercomponentsdescribedabove.Thecontentofthisfileisshownhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="test:pipeline"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpointservice="test:MyProviderService"

endpoint="myProvider"role="provider"

soap="false"destinationStyle="queue"

jmsProviderDestinationName="queueB"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="echo"

service="test:echo">

<sm:component>

<beanclass="org.apache.servicemix.components.

util.EchoComponent">

<sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:pipelineservice="test:pipeline"

endpoint="pipelineEndpoint">

<eip:transformer>

<eip:exchange-targetservice="test:echo">

<eip:transformer>

<eip:target>

<eip:exchange-target

service="test:MyProviderService">

<eip:target>

</eip:pipeline>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\08_Pipelineandtypeantasshownhere:

cdch15\08_Pipeline

ant

Thiswillcompileallthefiles,includingtheJMSclientprogram.Nowtotestthesample,firstbringServiceMixupbyexecuting:

cdch15\08_Pipeline

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrunasshownhere:

cdch15\08_Pipeline

antrun

Theoutputfortheabovecommandisshowninthefollowingscreenshot:

Asseeninthefigure,therequestandresponsemessagewillpassthroughthepipelinewhichwillbridgethetwoIn-OnlyMEPexchanges(requestandresponse)toanIn-OutMEPexchange(Echocomponent).

StaticRoutingSlipAstaticroutingslipcanrouteamessagecominginanIn-OutMEPthroughaseriesofconfiguredtargetservices.

NOTATION

EXPLANATIONYoumightbeawareoftheservletfilters,whichisakindofpipeandfilterconfigurationtodoprocessingatthepresentationtier.Sometimeswemayneedtodosimilar

processing,throughaseriesofprocessblocks.Theexactprocessingblocksthroughwhichthemessagehastoberoutedcanbedynamicbasedonthetypeofmessage.Inastaticroutingslip,theseprocessingblocksortargetservicesarefixed.TheServiceMixroutingslipusesIn-OutMEPsanderrorsorfaultssentbythetargetsarereportedbacktotheconsumer.Incaseoferrorstheroutingprocessisinterrupted.

ILLUSTRATIVEDESIGNWhentheAcmecustomerdropsitemsintotheshoppingcart,wemayalsoneedtoextendanyoffersordiscountsassociatedwiththeselecteditem.Thishastobedoneaftertheinitialinventorycheck.Wecanattacharoutingsliptoeachmessagesothatthemessagesareroutedinseriesthroughtheinventorymoduleandtheoffermodule.Thisisexplainedinthefollowingfigure:

SAMPLEUSECASEThesampleusecasewillhavefollowingcomponents:

HTTPclient:ThisisanexternalHTTPclient,placingtheXMLmessagesontotheHTTPconnectorcomponentconfiguredwithintheESB.

HTTPconnector:ThisisaServiceMixHTTPcomponentlisteningonport8912.AnyincomingmessagestothisqueuewillberoutedtothenextcomponentintheflowchainwhichistheStaticRoutingSlip.

Staticroutingslip:TheStaticRoutingSlipisaservicemix-eipcomponent.Onreceivinginmessages,theStaticRoutingSlipwillattachroutingslipswhicharepre-configuredtothemessage.NowtheESBcanroutethemessageinseriesthroughtheservicesspecifiedthroughtheslips.

Receivercomponent:MultipleinstancesofthereceivercomponentareconfiguredintheESB.Theroutingslipattachesslipscorrespondingtoonlyafewofthereceiverswitheveryincomingmessage.Hencethemessagesareforwardedthroughthesereceiverinstancesonly,othersareneglected.

Oncompletingtheflow,theHTTPclientcanretrievebackthemessagefromtheHTTPconnectorasshowninthefollowingfigure:

SAMPLECODEANDCONFIGURATIONWeconfigurethepipelineintheservicemix.xmlfile,alongwithothercomponentsdescribedabove.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns="http://xbean.org/schemas/spring/1.0"

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:test="http://xslt.servicemix.apache.binildas.com"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0">

<classpath>

<location>.</location>

</classpath>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:containername="jbi"

monitorInstallationDirectory="false"

createMBeanServer="true"useMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpeccomponentName="httpReceiver"

service="test:httpBinding"

endpoint="httpReceiver"

destinationService="test:routingSlip">

<sm:component>

<beanclass="org.apache.servicemix.components.

http.HttpConnector">

<propertyname="host"value="localhost"/>

<propertyname="port"value="8912">

<bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver1"

service="test:receiver1">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>1</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver2"

service="test:receiver2">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>2</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver3"

service="test:receiver3">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="MyReceiver">

<propertyname="name">

<value>3</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:static-routing-slip

service="test:routingSlip"

endpoint="routingSlipEndpoint">

<eip:targets>

<eip:exchange-targetservice="test:receiver1"/>

<eip:exchange-targetservice="test:receiver3">

<eip:targets>

</eip:static-routing-slip>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

DEPLOYANDRUNTHESAMPLETobuildthesample,changedirectorytoch15\09_StaticRoutingSlipandtypeantasshownhere:

cdch15\09_StaticRoutingSlip

ant

Thiswillcompileallthefiles,includingtheJMSclientprogram.Nowtotestthesample,firstbringServiceMixupbyexecuting:

cdch15\09_StaticRoutingSlip

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

Nowinadifferentcommandpromptexecuteantrun.

cdch15\09_StaticRoutingSlip

antrun

Theoutputfortheabovecommandisshowninthefollowingscreenshot:

IfyouobservetheESBconsoleyoucanseethattheESBroutesthemessageinseriesthroughtheservicesspecifiedthroughtheslips(test:receiver1andtest:receiver3).

SummaryIntegrationrequiresalevelofthinkingdifferentfromthetraditionalsoftwareengineeringwhereyouhavetothinkintermsofsoftware"plugs"and"sockets".IhavetoadmitthatmyuniversitycoursesinMachineDesignhelpedmealottothinkofthesoftwareintegrationproblemintermsof"shafts"andcoupling"—infact,theircounterpartsinEAI.Ihopeyoutooadmitthatafterreadingthischapter.So,thenexttimewhenyouwanttointegratesoftwarecomponentsthinkintermsofEAIandpatterns.Moreover,tryto"selectandassembleintegrationbuildingblocks"ratherthanhandcodingandhardwiringendpoints.Thiswillhelpyoutointegrateinaloosely-coupledmannerwhichwillfacilitateeasyservice

collaborationandorchestration.ThenextchapterwillshowyouasampleofaggregatingmultipleservicesontheESBusingtheEAIpatternsandguidelineswhichwelearnedinthischapter.

Chapter16.SampleServiceAggregationInthepreviouschapterswecoveredmanyJBIcomponentsinServiceMixandalsosawafewusefulusecasestohelpsolvereallifeproblemsusingtheESBpatterns.AnotherusefulapplicationofESBistoprovidea"ServicesWorkbench"whereinwecanusevariousintegrationpatternsavailabletoaggregateservicestocarryoutbusinessprocesses.Wewilllookintosuchasampleusecaseinthischapter.

Wewilllookatthefollowingtopicsinthebusinessintegrationsample:

Solutionarchitecture

JBI-basedESBcomponentarchitecture

Understandingthemessageexchange

Deployandrunthesample

ProvisionServiceOrder—BusinessIntegrationSampleTodemonstratetheserviceaggregation,wewillchooseatypicalbusinessintegrationscenariohappeningasanoutcomeofacustomerattemptingtomakeaweborderentry.Letus

takethescenarioofaCommunicationServiceProvider(CSP)providingawebaccesschannelforitscustomerstoorderVoiceoverIP(VOIP)service.

Wewillconsiderasingleprocessofordergeneration,whichisacoreprocessinanordermanagementsystem(OMS).Theordergenerationprocessacceptsandissuesorders.Thisprocesscanbedividedintostepssuchasorderentryandvalidation.Ifweconsiderasinglestepsuchasthevalidation,itcanbedecomposedintomultiplevalidationactivitiestobeperformedbymorethanonethird-partyserviceproviders.Thismakessenseintoday'sservice-orientedenvironment,whereservicesareprovidedbymultiplevendorsandasingleaggregateserviceiscomposedofmultipleline-itemservicesofferedbymultiplevendors.

Inourexamplescenario,letusconsiderthreevalidationservicestobedone:

Addressvalidation

Creditcardvalidation

Bankhistoryvalidation

Theabovefine-grainedservicesareofferedbydifferentthird-partyvendors.Hence,asperindustrystandards,thebestwaytoaccessthoseservicesisusingSOAPoverHTTP.TheAddressServicevalidatestheaddressenteredbytheuserandalsocheckstoseewhethertheVOIPservicecanbeprovidedintherequestedarea.CreditGatewayisacompositeservice,andthesuccessfuloperationofthisservicedependsupontheresponsesfromtwootherthird-partyvendorservicescalled

"CreditAgency"and"BankAgency".TheCreditAgencychecksforthecreditworthinessofthecustomer,andtheBankAgencychecksforthecustomer'sbankingtransactionhistory.

SolutionArchitectureLetusfirstlookatwhatJBI-basedtechnicalcomponentsarerequiredforframingoursolutionarchitecture.Thisisshowninthefollowingfigure:

Theabovefigureshowsthesolutionarchitectureforthebusinessscenariodescribedearlier.InordertoframetheESBsolutionarchitectureforthesamplescenario,wewillfirstlisttheindividualcomponentsrequired.IndividualESBcomponentsarechosenbasedonthetransportrequirementsto

facilitatetheinformationflow.Thesecomponentsareexplainedinthefollowinglist:

Endpoint:Anendpointconnectsservicesacrosssystems,applications,andenterprisestogether.Anendpointexposesstandardinterfacesandhidesalltransport-specificaspects,thusprovidinganabstractplug-inpoint.Theendpointsarerequiredforthesamplebusinessscenariotoaccesstheaddress,credit,andbankservice.

Translator:ThetranslatorsconvertbetweenmessageformatsandaresynonymouswiththeadapterpatternlistedintheGangofFourDesignPatternsbook.Inthesamplearchitecture,thevalidationbrokerserviceneedstotalktotheexternalservicesthroughtheSOAPprotocol.Hence,theJavaobjectsneedtobetranslatedtoXMLformat,andviceversa.

Normalizer:Thecreditandbankservicesdealwithmessagesthathavethesamemeaningbutdifferentformats.Thisisbecausedifferentexternalsystemshavetheirownmessageformats.Thismeansthemessagesareindifferentformats,butaresemanticallyequal.Anormalizerroutessemanticallyequalmessagestodifferentmessagetranslators.

Recipientlist:Inscenarioswhereweneedtoroutemessagetomultipleendpoints,wewillusearecipientlist.Therecipientscanbespecifieddynamicallyalso.Inourscenario,weneedtosendthesamemessagetoboththecreditandbankservices.Here,oncetheendpointsaredefined,therecipientlistwillforwardthemessagetoallchannelsassociatedwiththerecipientsinthelist.

Aggregator:AstheCreditGatewaydependsuponthecombinedoutcomeoftwootherservices(CreditAgencyandBankAgency),weneedtouseastatefulfiltertocollectandstoreindividualmessagesuntilacompletesetofrelatedmessageshasbeenreceived.Anaggregatordoesthisjobbycombiningtheresultsofindividual,butrelatedmessagessothattheycanbeprocessedasawhole.

JBI-basedESBComponentArchitectureThefollowingfigureshowsthevariousJBIcomponentswe

assembletodesigntheintegrationsolutionfortheordervalidationbusinessprocess.Thefunctionalityofthesecomponentsisalreadydiscussed.Weareshowingthemessageflowinthisdiagram.WewilldetailoutthemessageflowsinthenextsectionwiththehelpofaUMLdiagram.

UnderstandingtheMessageExchangeAsit'ssaidthatadiagramspeaksathousandwords,sodoestheUMLdiagramthatnarratescomplexmessageflowsinasimplemanner.Hence,letusunderstandthemessageexchangeswiththehelpofsequencediagrams.TheSequence1isshowninthefollowingfigure:

TheSequence1showsthemain"Controlflow",orchestratedbythebroker.ThecontrolcodeisprovidedwithintheonMessageExchangemethodinthebrokerandisreproducedinthefollowingcode:

publicclassSyncVoipBrokerextends

ComponentSupportimplements

MessageExchangeListener

{

{

privateMapaggregations=

Collections.synchronizedMap(newHashMap());

privateJBIContainercontainer;

privateStringname;

privateStringaddressNamespaceURI;

privateStringaddressLocalPart;

privateStringcreditGatewayNamespaceURI;

privateStringcreditGatewayLocalPart;

privateObjectpayLoad;

privatebooleancreditVetoed;

privatevolatileintstack=0;

publicvoidonMessageExchange(MessageExchange

exchange)throwsMessagingException

{

System.out.println("SyncVoipBroker.onMessageExchange.

ExchangeId:X:"+exchange.getExchangeId());

serviceaggregation,businessintegration

samplemessageexchange,sequence1ServiceEndpoint

serviceEndpoint=null;

if(exchange.getStatus()==ExchangeStatus.DONE)

{

System.out.println("SyncVoipBroker.onMessageExchange.

ExchangeStatus.DONE");

dispose();

return;

}

if(exchange.getStatus()==ExchangeStatus.ERROR)

{

System.out.println("SyncVoipBroker.onMessageExchange.

ExchangeStatus.ERROR");

return;

}

if(exchange.getRole()==Role.PROVIDER)

{

System.out.println("SyncVoipBroker.onMessageExchange.

Role.PROVIDER");

processInputRequest(exchange);

}

else

{

System.out.println("SyncVoipBroker.onMessageExchange.

System.out.println("SyncVoipBroker.onMessageExchange.

Role.CONSUMER");

serviceEndpoint=exchange.getEndpoint();

if

(serviceEndpoint.getServiceName().getLocalPart().

equals(addressLocalPart))

{

processAddressValidationResponse(exchange);

}

elseif

(serviceEndpoint.getServiceName().getLocalPart().

equals(creditGatewayLocalPart))

{

processCreditGatewayResponse(exchange);

}

else

{

processServiceRequest(exchange);

}

}

}

}

IftheExchangeStatusis"DONE"or"ERROR"fortheinitialMessageExchange,wesimplylogandreturn.Ifnot,thenthebrokercomponentcantakepartinthemessageexchangeintworolesnamelytheproviderortheconsumer.

Fortheconsumerrole,therearemultiplepathswhichwillbeexplainedlater.Butfortheproviderrole,thebrokertransferscontroltoSequence2listedinthefollowingfigure:

InthenormalflowwhenaclientsendsamessagetotheESB,theonMessageExchangemethodinthebrokerwillbeinvokedintheproviderrole.WelabelthismessageExchangeastheRootExchange(todifferentiatethisexchangefromothernestedexchanges,whichwillbedescribedshortly)andkeepapointerofthatinaMapforfuturereference.TheXMLpayloadwhichweretrievefromthenormalizedMessageisconvertedtoJavaobjectsusingtheXStreamJavaXMLbindingutilitiesandstoredforfuturereference.WethencreateanewInOutexchangewithaddressastheLocalPartandsendittothedeliveryChannel.Thefollowingcodesnippetdetailsoutthesesequenceofevents:

publicclassSyncVoipBrokerextends

publicclassSyncVoipBrokerextends

ComponentSupportimplements

MessageExchangeListener

{

privatevoidprocessInputRequest(MessageExchange

exchange)throwsMessagingException

{

NormalizedMessagecopyMessage=

exchange.createMessage();

NormalizedMessageinNormalizedMessage=

exchange.getMessage("in");

getMessageTransformer().transform(exchange,

inNormalizedMessage,copyMessage);

Sourcecontent=copyMessage.getContent();

StringcontentString=null;

if(contentinstanceofDOMSource)

{

contentString=XMLUtil.retreiveSoapContent(

((DOMSource)content).getNode());

payLoad=

XStreamUtil.xmlToObject(contentString);//Cacheit

}

CustomerTOcustomerTO=((ServiceParamTO)

payLoad).getCustomer();

AddressTOaddressTO=customerTO.getAddress();

StringxmlAddress=

XStreamUtil.objectToXml(addressTO);

SourceaddressSource=newStreamSource(new

ByteArrayInputStream(xmlAddress.getBytes()));

StringcorrelationId=null;

if(exchange.getStatus()==

ExchangeStatus.ACTIVE)

{

correlationId=exchange.getExchangeId();

aggregations.put(correlationId,exchange);

InOutinout=createInOutExchange(newQName(

addressNamespaceURI,addressLocalPart),null,

null);

inout.setProperty(Constants.CORRELATION_ID_KEY,

correlationId);

inout.setProperty(Constants.CORRELATION_ID_KEY,

correlationId);

correlationId);

NormalizedMessagemsg=inout.createMessage();

msg.setContent(addressSource);

inout.setInMessage(msg);

send(inout);

}

System.out.println("SyncVoipBroker.processInputRequest.

correlationId:"+correlationId);

}

}

NotethenewlycreatedmessageExchangewhichwillagaininvoketheonMessageExchangemethodoftheaddress(whichinturncallsthetransformmethodofAddress—Sequence3).WhentheAddressservicereturns,theonMessageExchangemethodinthebrokerwillbeinvokedagain,butthistimeintheconsumerrole—consumertotheaddress.ThisdifferenceissubtlebutimportantbecauseinanIn-Outexchange,itistheconsumerwhohastoendamessageexchangewitha"done"or"error"status.TheAddressserviceissimpleandisshowninSequence3.ThefollowingfigureshowstheSequence3UMLdiagram:

InAddressservice,wevalidatetheaddressandtheresultofthevalidationissetasapropertyinthe"out"messageoftheMessageExchange.Thisisshowninthefollowingcode:

publicclassAddressValidationServiceextends

TransformComponentSupport

{

protectedbooleantransform(MessageExchange

exchange,NormalizedMessagein,NormalizedMessage

out)throwsMessagingException

{

StringcorrelationId=

(String)exchange.getProperty(

Constants.CORRELATION_ID_KEY);

System.out.println("AddressValidationService.transform.

correlationId:"+correlationId);

Sourcecontent=in.getContent();

StringcontentString=null;

AddressTOaddressTO=null;

if(contentinstanceofStreamSource)

{

contentString=XMLUtil.formatStreamSource(

(StreamSource)content);

(StreamSource)content);

addressTO=(AddressTO)XStreamUtil.

xmlToObject(contentString);

}

else

{

log.debug("AddressValidationService-

content.getClass():"+content.getClass()+";

content:"+content);

}

out.setProperty(Constants.ADDRESS_VALIDATED_KEY,

Boolean.TRUE);

serviceaggregation,businessintegration

samplemessageexchange,sequence3returntrue;

}

}

WhentheAddressservicereturns,theonMessageExchangemethodinthebrokerwillbeinvoked(Sequence1).NowasthebrokercomponentisintheconsumerroleandtheLocalPartis"address",thecontrolflowstotheprocessAddressValidationResponsewhichisgiveninSequence4.

InprocessAddressValidationResponsewecheckwhethertheaddressisvalidated.Ifnot,wesettheXMLmessage"<AddressNotValidated/>"atthenormalizedMessagetotheRootExchangesothatthemessageexchangeflowwillbecompletedandcontrolflowsbacktothedeliveryChannelfirstandthentotheclient.Ifaddressisvalidated,wecreateanewInOutexchangewithcreditGateWayastheLocalPartandsendittothedeliveryChannel.

Inboththescenariosabove,notethatwesetthe(AddressValidation)messageExchangestatusto"done".Thecodelistinginthefollowingshowsprocessingtheaddressvalidationresponse:

publicclassSyncVoipBrokerextends

ComponentSupportimplements

MessageExchangeListener

MessageExchangeListener

{

privatevoid

processAddressValidationResponse(MessageExchange

exchange)throwsMessagingException

{

StringcorrelationId=(String)

getProperty(exchange,

Constants.CORRELATION_ID_KEY);

System.out.println("SyncVoipBroker.

processAddressValidationResponse.correlationId:

"+correlationId);

booleanisAaddressValidated=((Boolean)

getOutProperty(exchange,

Constants.ADDRESS_VALIDATED_KEY)).booleanValue();

MessageExchangerootExchange=null;

if(isAaddressValidated)

{

InOutinout=createInOutExchange(newQName(

creditGatewayNamespaceURI,

creditGatewayLocalPart),null,null);

inout.setProperty(Constants.CORRELATION_ID_KEY,

correlationId);

NormalizedMessagemsg=inout.createMessage();

inout.setInMessage(msg);

send(inout);

}

else

{

rootExchange=(MessageExchange)aggregations.

get(correlationId);

serviceaggregation,businessintegration

samplemessageexchange,sequence

4NormalizedMessageresponse=

rootExchange.createMessage();

response.setContent(newStringSource("

<AddressNotValidated/>"));

rootExchange.setMessage(response,"out");

send(rootExchange);

aggregations.remove(correlationId);

}

done(exchange);

done(exchange);

}

}

Assumingthe"AddressValidated"scenarioasthenormalflow,thenewlycreatedMessageExchangewillnowagaininvoketheonMessageExchangemethodoftheCreditGateway(whichinturncallsthetransformmethodofcreditGateway—Sequence5).WhentheCreditGatewayservicereturns,theonMessageExchangemethodinthebrokerwillbeinvokedagain,thistimealsointheconsumerrole—consumertotheCreditGatewayservice.TheCreditGatewayserviceissimple.TheSequence5isshowninthefollowingfigure:

IntheCreditGatewayservicewecreatearecipientlistandsetitasapropertyinthe"out"messageoftheMessageExchange.Thisisshowninthefollowingcode:

publicclassCreditGatewayextends

TransformComponentSupport

{

privateMapendPoints;

publicvoidsetEndPoints(MapendPoints)

{

this.endPoints=endPoints;

}

protectedbooleantransform(MessageExchange

exchange,NormalizedMessagein,NormalizedMessage

out)throwsMessagingException

{

StringcorrelationId=

(String)exchange.getProperty(

Constants.CORRELATION_ID_KEY);

System.out.println("CreditGateway.transform.correlationId

:"+correlationId);

out.setProperty(Constants.RECIPIENTS_KEY,

getRecipients());

returntrue;

}

privateQName[]getRecipients()

{

QName[]recipients=newQName[endPoints.size()];

StringtheNamespaceURI=null;

StringtheLocalPart=null;

inttimes=0;

for(Iteratoriterator=

endPoints.keySet().iterator();

iterator.hasNext();)

{

theLocalPart=(String)iterator.next();

theNamespaceURI=(String)

endPoints.get(theLocalPart);

recipients[times++]=newQName(theNamespaceURI,

theLocalPart);

}

returnrecipients;

}

}

Herewegenerateastaticrecipientlist.Therecipientlistisconfiguredintheservicemix.xmlfilefortheCreditGatewaycomponentasshownhere:

<sm:activationSpeccomponentName="creditGateWay"

endpoint="creditGateWay"

service="binil:creditGateWay">

<sm:component>

<bean

class="com.binildas.esb.servicemix.serviceassembly.

voipservice.CreditGateway">

<propertyname="name">

<value>Credit</value>

</property>

<propertyname="endPoints">

<map>

<entrykey="creditAgency">

<value>http://www.binildas.com/voipservice</value>

</entry>

<entrykey="bankAgency">

<value>http://www.binildas.com/voipservice</value>

</entry>

</map>

</property>

</bean>

</sm:component>

</sm:activationSpec>

WhentheCreditGatewayservicereturns,theonMessageExchangemethodinthebrokerwillbeinvoked(Sequence1).NowasthebrokercomponentisagainintheconsumerroleandtheLocalPartis"creditGateWay",thecontrolflowstotheprocessCreditGatewayResponsewhichisgivenin

Sequence6.Thisisshowninthefollowingfigure:

Ournextaimistoroutethemessagetoallthetargetsdefinedintherecipientlist.WecreateasmanynewInOutexchangesasthereareentriesintherecipientlistandsendthemtothedeliverychannel.Thefollowingcodesnippetdetailsoutthesesequenceofevents:

publicclassSyncVoipBrokerextends

ComponentSupportimplements

MessageExchangeListener

{

privatevoid

processCreditGatewayResponse(MessageExchange

exchange)throwsMessagingException

{

StringcorrelationId=(String)

getProperty(exchange,

Constants.CORRELATION_ID_KEY);

System.out.println("SyncVoipBroker.

System.out.println("SyncVoipBroker.

processCreditGatewayResponse.correlationId:"+

correlationId);

QName[]recipients=(QName[])

getOutProperty(exchange,

Constants.RECIPIENTS_KEY);

CreditCardTOcreditCardTO=((ServiceParamTO)

payLoad).getCreditCard();

StringxmlCreditCard=

XStreamUtil.objectToXml(creditCardTO);

SourcecreditCardSource=null;

InOutinout=null;

NormalizedMessagemsg=null;

for(intqNames=0;qNames<recipients.length;

qNames++)

{

inout=createInOutExchange(recipients[qNames],

null,null);

inout.setProperty(Constants.CORRELATION_ID_KEY,

correlationId);

msg=inout.createMessage();

creditCardSource=newStreamSource(new

ByteArrayInputStream(xmlCreditCard.getBytes()));

msg.setContent(creditCardSource);

inout.setInMessage(msg);

stack++;

send(inout);

}

done(exchange);

}

}

Herewesendthecreditcarddetailstotherecipients(BankAgency&CreditAgency).

ThenewlycreatedmessageexchangeswillnowinvoketheonMessageExchangemethodoftheBankAgency&CreditGateway(whichinturncallsthetransformmethodof

BankAgency&CreditAgencyrespectively)whichisagainsimpleandisshowninSequence7andSequence8.Thecodeisnotreproducedhere,sincetheyareverytrivial.TheSequence7isshowninthefollowingfigure:

TheSequence8isshowninthefollowingfigure:

WhentheBankAgencyortheCreditAgencyservicesreturns,theonMessageExchangemethodinthebrokerwillbeinvokedagainintheconsumerrole—consumertotheBank

AgencyandCreditAgency.Inboththescenarios,thecontrolwillbethetransformmethod.

TheSequence9isshowninthefollowingfigure:

LetusnowlookintothecodeofprocessServiceRequestindetail:

publicclassSyncVoipBrokerextends

ComponentSupportimplements

MessageExchangeListener

{

privatevoid

processServiceRequest(MessageExchangeexchange)

throwsMessagingException

{

StringcorrelationId=(String)

getProperty(exchange,

Constants.CORRELATION_ID_KEY);

Constants.CORRELATION_ID_KEY);

System.out.println("SyncVoipBroker.processServiceRequest.

correlationId:"+correlationId);

Booleancreditauthorized=(Boolean)

getOutProperty(exchange,

Constants.CREDIT_AUTHORIZED_KEY);

Booleangoodhistory=(Boolean)

getOutProperty(exchange,

Constants.GOOD_HISTORY_KEY);

MessageExchangerootExchange=(MessageExchange)

aggregations.

get(correlationId);

done(exchange);

stack--;

if(((creditauthorized!=null)&&!

(creditauthorized.equals(Boolean.TRUE)))||

((goodhistory!=null)&&!

(goodhistory.equals(Boolean.TRUE)))){

creditVetoed=true;

System.out.println("SyncVoipBroker.processServiceRequest

-creditVetoed:"+creditVetoed);

}

if(0==stack)

{

NormalizedMessageresponse=

rootExchange.createMessage();

if(creditVetoed)

{

response.setContent(newStringSource("

<ServiceNotProvisioned/>"));

}

else

{

response.setContent(newStringSource("

<ServiceProvisioned/>"));

}

rootExchange.setMessage(response,"out");

send(rootExchange);

aggregations.remove(correlationId);

}

}

}

}

Here,basedontheoutcomeofthepreviousserviceresponseswecandecidewhethertheservicecanbeprovisionedornotandaccordinglywecancreateanXMLmessage.Nowcomesthedifference—wecreateanormalizedmessageoutoftheRootExchange(wearenotgoingtocreateanewmessageexchange,sincewearealmostdonewiththeprocess),settheXMLmessageasitscontentandcallsendontherootExchange.

TheRootExchangewillagainberoutedthroughthedeliverychannelbacktotheonMessageExchangeoftheBroker,butthistimethemessageexchangestatusisalreadysetas"DONE".SoasshowninSequence1,thebrokernowreturnsbacktothedeliverychannelandthedeliverychannelinturnsendsbackanyresponsetotheclient.

Thiscompletestheentireprocess.

DeployingandRunningtheSampleAsafirststep,ifyouhaven'tdoneitbefore,editexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter)andchangethepathstheretomatchyourdevelopmentenvironment.Nowtobuildtheentirecodebaseanddeploythesampleinasinglego,changedirectorytoch16\voipservicewhichcontainsatop-levelbuild.xmlfile.Executeantthere.

cdch16\voipservice

ant

Now,bringuptheServiceMixcontainerbyexecutingthebroker.xmlfilecontainedinthesamefolder.

cdch16\voipservice

%SERVICEMIX_HOME%/bin/servicemixbroker.xml

TheClient.htmlfileprovidedagaininthesamefoldercanbeusedtosendmessagestotestthedeployedservice.

ThemessageexchangeswedescribedintheprevioussectioncanbeunderstoodbetterbylookingattheServiceMixconsoleloggingshowninthefollowingscreenshot:

SummaryMOMhasbeenservingasagreatenablerforcreatinglooselycoupledapplicationsformanyyears.NowMOMprovidesustheEAIpatterntointegratenotonlyapplicationsbutalsoservicesandcomponentsinaseamlessmanner.

Distributedcomponentsarethenormintoday'senterprise

computing,aggregating,andorchestratingthemessageflowsacrosssuchmultiplecomponentsprovideuswithanewflexibilityindefiningbusinessprocess—byseparatingoutindividualservicesintomultiplecomponentsandthusreducingtheoverallcomplexityoftheprocess.

Weusethe"divideandrule"principletomanagethecomplexitybysplittingoutthefunctionalityintomultiplecomponentsandservices.However,thenthesedistributedcomponentshavetointegratetogethertoprovideaggregateorcompositeserviceswhichwecandoattheESB-level.Youhaveseensuchasampleinthischapter.

InthenextchapterwewilllookattheJBIbusinaslightlydifferentperspective—inanon-functionaloraQOSperspective.

Chapter17.Transactions,Security,Clustering,andJMXNobookonprogrammingwithanyframeworkwillbecompletewithoutamentionofthevariousnonfunctionalandQOSfeaturessupportedbytheframework.InthischapterwewillvisitafewselectedQOSfeatureswhichhaveanimpactontheprogramminganddeploymentaspectsusingtheServiceMixESB,whicharelistedasfollows:

Transactions

Security

Clustering

JMX

Infact,ifwehavetoaddresstheabovefeaturesexhaustivelythenwemayneedmanypages(orasinglebookbyitself).However,asthisbookisintendedtocovermanyotheraspects,wewilllimitourdiscussiontoasinglechapter.AtthesametimewewillseethatthereaderwillnotonlyhaveanoverviewoftheabovefeatureswithinServiceMix,butalsoisequippedwiththetools,codesamples,anddesignaspectssoastoenablehimforfurtherreadinganddevelopment.

Inthischapterwewilllookintothefollowing:

CrosscuttingconcernsinServiceMix

Samplesdemonstratingtransactions,security,clustering,andJMX

CrossCuttingConcerns—SupportInsideServiceMixThischapterisslightlydifferentfromothersbecausealmostalltheotherchaptersweredealingwithaparticularwayofbindingservicestoServiceMix.Inthischapterwearegoingtoaddressprogrammingand/ordeploymentconcernswhichcanbeappliedacrossanyorallofthebindingmechanismscoveredintheotherchapters.

Justasitispossibleinnormalprogrammingsuchaswebcomponentdevelopmentorserver-sidebusinesscomponentdevelopment,wecanalsoattachvariousQOSfeaturestothecomponentdeploymentmodelinServiceMix.ThepeculiarthingwiththeseQOSfeaturesisthattheyarenothardwiredthroughcodealongwiththeBCsorSEs,butappliedoverthecomponentsinadeclarativemanner.TheadvantageisthatthecharacteristicsoftheseQOSfeaturescanbeeasilychangedbyalteringtheparticularconfiguration.

LetusnowlookintotheselectedQOSfeaturesandtheirsupportwithinServiceMix.

TransactionsTransactionsguaranteeatomicityoftheoperations(messageflows)betweenthecomponents.Weknowthatvarious

componentscanbepluggedintotheJBIbuswhichcantakepartinthemessageexchange.Transactionscanbeassociatedwiththesemessageexchangeflows.Thescopeandsynchronicityofthesetransactionsmainlydependsuponwhich"send"primitiveweusetoexchangemessagesbetweencomponents.

TheServiceMixJBIprovidesanoptiontosettransactionsatthecontainer-level.ThefollowinglistingshowshowtoenlistJBIexchangesintransactions.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0">

<sm:containerid="jbi"embedded="true"

depends-on="jndi,broker"

autoEnlistInTransaction="true"

transactionManager="#transactionManager">

</sm:container>

<jencks:transactionManager

id="transactionManager">

<beans>

WecansettheautoEnlistInTransactionattributefortheServiceMixJBIcontainertotruesothateverytimeaJBIexchangeissent,itwillbeenlistedinthecurrenttransaction.

WecannowusesendorsendSynctosendthemessageexchangesanddependinguponwhichoneisused,thesemanticsoftransactionpropagationalsoisdifferent.

IfsendSyncisusedtosendanexchange,theimplied

semanticisthatthetransactionflowswiththeexchangeandthattheserviceproviderhastoanswersynchronouslyandalsoenlistanyrequiredresourcesinsidethetransaction.InChapter3wediscussedaboutthevariousflow(NMRFlows)optionsavailablewithinServiceMixofwhichtheJCAflowneedsspecialattention.Theservicemixjmscomponent,ifusedinaJCAflow,canstarttransactionswhereastransactionswithinasynchronousflowarenotcreatedbydefault.

ThefollowingfigureshowsthepropagationoftransactioncontextwhensendSyncisused:

Ifweusesend,thesendingofthemessagewillbeenlistedinthecurrenttransaction,butthemessageexchangeprocessing

willbedeferredandthenhandledinitsownthreaddisjointfromtheprevioustransaction.WehavetousetheJCAflowtousethetransactionswiththeasynchronousmessageexchanges.Asampleflowisshowninthefollowingfigure:

Programmingthetwotypesofsynchronicityoftransactioninthemessageexchangeareshowninthefollowinglist:

Programmingsynchronoustransactionalexchange:SynonymoustotheJDBCAPI,weneedtofirstgetahandletotheunderlyingTransactionManagerandthenmarkthetransactiontobegin.ThenwesendthemessageexchangeusingsendSyncfollowedbyacommitorarollback.Thesequencesofstepsareshownhere:

TransactionManagertxManager=

(TransactionManager)

(TransactionManager)

jbiContext.getTransactionManager();

tm.begin();

InOnlymessageExchange=createInOnly();

jbiContext.getDeliveryChannel().sendSync(messageExchange);

tm.commit();

Programmingasynchronoustransactionalexchange:Creatingasynchronoustransactionalexchangeissimilartothesynchronousmethod,butweusesendinsteadofsendSync.

TransactionManagertxManager=

(TransactionManager)

jbiContext.getTransactionManager();

tm.begin();

InOnlymessageExchange=createInOnly();

jbiContext.getDeliveryChannel().send(messageExchange);

tm.commit();

Thelatersectionsinthischapterwillhaveworkingsampleswhichwillmakeclearthepointsexplainedhere.

SecurityServiceMix'sHTTPcomponentnamelyservicemix-httpprovidesfacilitytoconfiguresecurity.Letuslookatafewofthemlistedhere:

HTTPbasicauthentication:HTTP1.1specificationsdefinesbasicauthentication.Asperthat,whenaclienttriestoaccessaresourcemarkedasprotectedintheserver,theserverpromptsforausernameandpasswordcombination.Thisisfollowedbythebrowserpromptingwithausernameandpasswordentryformwheretheusercanentertherelevantinformationandsubmit.Iftheusernameandpasswordenteredbytheuseris

authenticatedbytheserver,accesswillbegrantedtotherequestedresource.Otherwise,dependingupontheserver'spolicy,thepromptwillberepeatedforafewtimes(usuallythree).ThemaindrawbackwithHTTPbasicauthenticationisthatthepasswordsaresentacrossthenetworkbase64encoded,whichisakindofplaintextformat.Asthepasswordsarenotencrypted,theyarevulnerabletohacks.Henceasanadditionalprecaution,wecaneitherdoencryptionorusesomeotherstrongermechanism.

Fortheservicemix-httpcomponent,wecanconfigurebasicauthenticationbyconfiguringtheendpointasshowninthefollowingcode:

<http:endpointservice="test:httpConsumer"

endpoint="httpConsumer"

targetService="test:echo"role="consumer"

locationURI="http://localhost:8198/Service/"

authMethod="basic"

defaultMep="http://www.w3.org/2004/08/wsdl/in-

out">

</http:endpoint>

Inthiscase,beforetheservicemix-httpcomponentroutestherequesttothetargetService,abasicauthenticationchallengeisinitiatedbytheserverandtherequestwillberoutedtothetargetServiceifandonlyiftheusernameandthepasswordenteredbytheusermatcheswithwhatisconfiguredinthecontainer.

SSL:ServiceMixcanbeconfiguredtousesecuretransportusingSSL.

TheHTTPconsumerrolefortheservicemix-httpcomponentcanbeconfiguredtouseSSLasfollows:

<http:endpoint

service="test:YourConsumerService"

endpoint="yourConsumer"role="consumer"

locationURI="https://localhost:8193/Service/"

defaultMep="http://www.w3.org/2004/08/wsdl/in-out">

<http:ssl>

<http:sslParameters

keyStore="classpath:com/binildas/esb/

servicemix/security/server.keystore"

keyStorePassword="keystorepassword">

<http:ssl>

</http:endpoint>

Intheconsumerrole,test:YourConsumerServicewillbesetasthedestinationfortheaboveconsumerafterthemessageisreceivedthroughtheSSLtransport.

Similarly,theHTTPproviderrolefortheservicemix-httpcomponentcanbeconfiguredtouseSSLasfollows:

<http:endpoint

service="test:YourProviderService"

endpoint="yourProvider"role="provider"

locationURI="https://localhost:8193/Service/"

defaultMep="http://www.w3.org/2004/08/wsdl/in-out">

<http:ssl>

<http:sslParameters

keyStore="classpath:com/binildas/esb/

servicemix/security/server.keystore"

keyStorePassword="keystorepassword"

trustStore="classpath:com/binildas/esb/

servicemix/security/client.keystore"

trustStorePassword="truststorepassword">

<http:ssl>

</http:endpoint>

WewillhaveaworkingsampledemonstratingHTTPbasicsecuritylaterinthischapter.

ClusteringArchitectinganddesigninganapplicationbylookingattheNonFunctionalRequirements(NFR)alongwiththeusualfunctionalrequirementsisimportanttoensurefailsafeoperationundernormalaswellasabnormalusageconditions.

Therecanbespecifichoursinadayorspecificmonthsduringayearwhenyourapplicationwillreceivemorehitsthannormal.Theapplicationsneedtobedesignedtakingthisintoaccount.

Thescalabilityandavailabilityofanyapplicationdependsonthemultiplelayersintheapplicationdeploymentstack.Thefollowinglistgivesafewofthemainaspects:

Applicationalgorithmsanddesignpatterns.

Applicationframeworksforfunctionalitiessuchascaching,sessionreplication,andpersistence.

Operatingsystemsupportprovidingheaplimit,greenthreads,andnativethreads.

Hardwareinfrastructure,providing32or64bitwordcapability.

Theabovelistisneverexhaustive,butjustthemainandevidentlayers.

Theavailabilityofanyapplicationdependsontheabilityofthedeploymentenvironmenttorecoverfromafailurewithaminimumamountofdowntimewithoutanydatacorruption.Softwareandhardwarearepronetofailure,butthatisnoreasontoshowback"Applicationnotavailable"messagestotheenduserthroughthebrowser.Suchascenariowillcreateunsatisfiedcustomerswhomightmigratetoacompetitor'sservice.Weallagreethatretaininganexistingcustomerisas(ormore)importantthangaininganewcustomer.

Onewaytoaddresssoftwareandhardwarefailureistoleveragetheindustry-leadingclusteringsolutionstodeliver

best-in-classhighavailability,manageability,andperformanceforapplicationsinenterpriseandapplicationservicegridenvironments.Ifwedon'twanttogoforsuchthird-partyclusteringservices,wecanalsoseewhetherourownchosenapplicationinfrastructure(suchasServiceMix)willprovideitsownclusteringfeatures.So,letusunderstandtheServiceMixclusterinmoredetail.

AServiceMixclusterisalogicalgroupingofmultipleServiceMixinstancesrunningsimultaneouslyandworkingtogetherthusprovidingincreasedscalabilityandreliability.Fromaclientoraconsumerperspective,theclusteristransparent.Thismeans,aServiceMixclusterappearstoclientstobeasingleServiceMixcontainerinstance.TheServiceMixinstancesthatparticipateinaclustercanrunonthesamemachine,orbelocatedondifferentmachines.YoucanalsoincreaseaServiceMixcluster'scapacitybyaddingadditionalServiceMixinstancestotheclusteronanexistingmachine,oryoucanalsoaddnewmachinestotheclustertohostnewServiceMixserverinstances.

IndividualcomponentsorapplicationcomponentsneedtobeinstalledtotheServiceMixserverinstancestakingpartinthecluster.ItisrecommendedtofollowauniforminstallationschemawherewewilldeploycomponentshomogenouslyintoalltheServiceMixserverinstancesinthecluster.However,thisisnotmandatoryasisshownintheclusteringsampleweprovidelaterinthechapter.TheexacttopologyanddeploymentschemaforaServiceMixclusterhastobedecidedbasedonwhatlevelofQOSfeatureswearetargetingfromeachofthedeployedcomponents.

TherearemultiplebenefitswhichwecanleveragefromaServiceMixclusteringtopology,afewofthemarelistedasfollows:

Scalability:Asoftwaresystemissaidtobescalableifitsperformancedoesnotdegradesignificantlyastheloadonthesystemincreases.ThescalabilityofaServiceMixclustercanbeincreaseddynamicallytomeetthedemand.YoucanaddtheServiceMixinstancestoaclusterwithoutinterruptionofthedeployedservice—theapplicationsandservicesalreadydeployedcontinuetorunwithoutimpacttotheexistingconsumers.

Highavailability:Availabilityisdefinedasthefractionoftimethesoftwaresystemisupandavailabletoitsconsumers.

NOTENOTE

Forexample,asystemwith99.99%availabilityoveraperiodof1yearwouldbeunavailablefor:

(1-0.9999)X1YearX365DaysX24HoursperDayX60MinutesperHour=52.56Minutes.

Formanysystemssuchastheweb-basede-commercesystemsa99.99%availabilitywouldbesufficientbutformanyothersystemslikethoseusedforlifesavingordefencepurposesahigher-levelofavailabilitywouldberequired.

InaServiceMixcluster,SEsandBCscanstillcontinuetoruninadifferentserverinstancewhenoneoftheserverinstancesfails.Asyoucandeploytheapplicationcomponentstomultipleserverinstancesinthecluster,ifaserverinstanceonwhichacomponentisrunningfails,anotherserverinstanceonwhichthatcomponentisdeployedcancontinuetheprocessingthusincreasingtheoverallsystemavailability.

Loadbalancing:LoadbalancingistheevendistributionofjobsandprocessesacrossthecomputingandnetworkingresourcesinyourServiceMixcluster.Forloadbalancingtooccur,theremustbemultiplecopiesofaServiceMixcomponentthatcanserveaparticularconsumer.InformationaboutthelocationandoperationalstatusofalltheServiceMixcomponentsmustbeavailablecentrallyandacross.

TosetupaServiceMixcluster,aJMSflowisused.TheJMSflowcollaboratesthecommunicationbetweenmorethanoneServiceMixJBIcontainerinstance.AmessagequeueisusedforeachJBIendpoint,sothatmultipleinstancesofthesamenamedcomponentdeployedindifferentinstancesoftheServiceMixintheclusterhaverequestsloadbalancedacrossthem.

InaServiceMixcluster,deploymenthappensinthesamewayaswedoinanormalServiceMixJBIcontainer(bothforPOJOandarchiveComponentdeployment)butallServiceMixcontainerinstancesintheclusterarenotifiedofadeployment.TheunderlyingJMSflowwillhandleautomaticrouting,loadbalancing,andfailoverofMessageExchange(s)betweenthedifferentServiceMixcontainersinstancesinthecluster.

IntheclustermodeallServiceMixinstancesparticipatingintheclustermusthaveauniquenameinthewholecluster.Letuslookintoasampleconfigurationtounderstandthiswell.Inourhypotheticalsamplecluster,assumethatwewillhavethreeServiceMixcontainersinstances.AsoneoftheseServiceMixinstancesalsomanagesaJMSconnectionbroker,wewillarbitrarilynamethatinstancewiththename"admin".

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<sm:containerid="jbi"name="admin"

flowName="jms?jmsURL=tcp:/localhost:61616"

useMBeanServer="true"createMBeanServer="true"

rmiPort="1111">

<sm:activationSpecs>

<!--othercode-->

</sm:activationSpecs>

</sm:container>

<beanid="broker"

class="org.apache.activemq.xbean.BrokerFactoryBean">

<propertyname="config"

value="classpath:activemq.xml">

<bean>

<beanid="jmsFactory"

class="org.apache.activemq.pool.PooledConnectionFactory">

<propertyname="connectionFactory">

<refbean="connectionFactory">

<property>

</bean>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

Theimportantthingtonotehereisthat,wefirstsettheflowNametobeofJMStypeandthensetthejmsURLtopointtothelocationwheretheJMSbrokerislistening.Now,wecanaddanynumberofinstancesfortheServiceMixtothecluster,simplybypointingthemtothesameJMSbroker.ForoursamplepurposewewillhavetwoinstancesforServiceMix

named"managed1"and"managed2".

Theflowsettingsformanaged1areshowninthefollowingcode:

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

>

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<sm:containerid="jbi"name="managed1"

flowName="jms?jmsURL=tcp:/localhost:61616"

useMBeanServer="true"createMBeanServer="true">

<sm:activationSpecs>

<!--othercode-->

</sm:activationSpecs>

</sm:container>

</beans>

Wewillhaveasimilarconfigurationformanaged2.Thisislistedinthefollowingcode:

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

>

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<sm:containerid="jbi"name="managed2"

flowName="jms?jmsURL=tcp:/localhost:61616"

useMBeanServer="true"createMBeanServer="true">

<sm:activationSpecs>

<!--othercode-->

</sm:activationSpecs>

</sm:container>

</beans>

Wewilllookintoaclusteringsamplewithcodelaterinthischapter.

JMXJMX(JavaManagementExtensions)technologyprovidestherequiredAPIsandtoolsforbuildingdistributed,web-based,modular,anddynamicsolutionsformanagingandmonitoringdevices,applications,andservice-drivennetworks.StartingwiththeJ2SEplatform5.0,JMXtechnologyisincludedintheJavaSEplatform.

TheServiceMixJBIContainerwillexposeinternalservicesandcomponentsthroughtheJMX.TheJBIContainercanbepassedasaJMXBeanServer.Alternatively,itcanbeconfiguredtocreateoneifitdoesn'texist.

ThefollowingcodewillcreatearemoteJMXConnectortotheJBIContainer:

StringjndiPath="jmxrmi";

JMXServiceURLurl=newJMXServiceURL

("service:jmx:rmi:///jndi/rmi://127.0.0.1:1099/"

+jndiPath);

JMXConnectorconnector=

JMXConnectorconnector=

JMXConnectorFactory.connect(url);

ConfiguringJMXinServiceMixisdoneinthejmx.xmlfileagainfoundintheconfdirectory.Thefollowingcodeshowshowtodothis:

<sm:jmxConnectorobjectName="connector:name=rmi"

serviceUrl="${jmx.url}"

threaded="true"

daemon="true"

depends-on="rmiRegistry,jndi"

environment="#jmxConnectorEnvironment"/>

Thejmx.urlisservice:jmx:rmi:///jndi/rmi://localhost:10

99/jmxrmi.

ThesearethedefaultsettingsforServiceMixversion3.x.Forversion2.x,jmx.urlchangestoservice:jmx:rmi:///jndi/rmi://localhost:10

99/defaultJBIJMX.

OnceServiceMixisupandrunning,thenyoucanuseanyJMXcompatibleconsoletoolstoconnecttotheServiceMixcontainer.Wewilldemonstratethislaterinthischapter.

SampleDemonstratingTransaction

Inthissectionwewilldemonstrateconfiguringtransactionsforamessageexchangeinanasynchronouspattern.

SampleUseCaseInthesamplescenariotodemonstratetransactions,wewillconfigureDefaultServiceMixClientwithintheJBIcontainerastheclientorconsumerfortheJBIbus.WewillfirststartatransactionandthenaskDefaultServiceMixClienttosendanInOnlymessageexchangetotheJBIbus.Wewilluse"send"heresothattheactofsendingthemessagewillbeenlistedinthecurrenttransaction,buttheprocessingofthemessageexchangewillbedeferredandhandledinaseparatethread.

WewillhaveaservicemixjmscomponentconfiguredintheproviderroletowhichtheDefaultServiceMixClientcantargetmessageexchange.WethenhaveaservicemixjmsintheconsumerroletowhichtheJMSproviderpipelinesmessages.FortheJMSconsumer,wehaveconfiguredaReceivercomponentusingthetargetServiceattribute.HenceanymessagesinthechainwillbeultimatelyroutedtotheReceivercomponent.

Thecomponentsetupisshowninthefollowingfigure:

Inthesample,weuse"send"forsendingthemessage.Hencesendingwillbeenlistedinthecurrenttransactionwhichincludesreceptionofthemessagebythebus.Anyfurtherprocessing,includingforwardingthemessagetothenextcomponentwillbedeferredandhandledinseparatethreads.

ConfigureTransactioninServiceMixAllthecomponentsspecifiedintheselectedusecaseareconfiguredintheservicemixjms.xmlfileasshownhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0"

xmlns:amq="http://activemq.org/config/1.0"

xmlns:amqra="http://activemq.org/ra/1.0"

xmlns:jencks="http://jencks.org/2.0"

xmlns:test="http://binildas.com/esb/servicemix/tx/

jms/inonlyasync">

<sm:containerid="jbi"embedded="true"

depends-on="jndi,broker"

autoEnlistInTransaction="true"

transactionManager="#transactionManager">

<sm:flows>

<sm:sedaFlow>

<sm:jcaFlow

connectionManager="#connectionManager"

jmsURL="tcp:/localhost:61616?

jms.asyncDispatch=true&amp;

jms.useAsyncSend=true">

<sm:flows>

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="consumerEP"

targetService="test:MyReceiverService"

role="consumer"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"processorName="jca"

connectionFactory="#connectionFactory"

resourceAdapter="#resourceAdapter"

bootstrapContext="#bootstrapContext"

synchronous="false">

<jms:activationSpec>

<amqra:activationSpecdestination="queue/A"

destinationType="javax.jms.Queue">

<jms:activationSpec>

</jms:endpoint>

<jms:endpointservice="test:MyProviderService"

endpoint="providerEP"role="provider"

processorName="jca"connectionFactory="

#connectionFactory"destinationStyle="queue"

jmsProviderDestinationName="queue/A">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="receiver"

service="test:MyReceiverService"

endpoint="receiverEP">

<sm:component>

<beanclass="org.apache.servicemix.tck.

ReceiverComponent">

<sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="client"

class="org.apache.servicemix.client.

DefaultServiceMixClient">

<constructor-argref="jbi">

<bean>

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<propertyname="entries">

<map>

<entrykey="jms/ConnectionFactory"

value-ref="connectionFactory">

<map>

</property>

</bean>

<amqra:managedConnectionFactoryid="activemqMCF"

resourceAdapter="#resourceAdapter">

<amqra:resourceAdapterid="resourceAdapter"

serverUrl="tcp:/localhost:61616?

jms.asyncDispatch=true&amp;

jms.useAsyncSend=true">

<jencks:connectionFactoryid="connectionFactory"

managedConnectionFactory="#activemqMCF"

connectionManager="#connectionManager">

<amq:brokerid="broker"persistent="false">

<amq:transportConnectors>

<amq:transportConnector

uri="tcp://localhost:61616">

<amq:transportConnectors>

</amq:broker>

<jencks:transactionManager

id="transactionManager">

<jencks:workManagerid="workManager"

transactionManager="#transactionManager">

<jencks:bootstrapContextid="bootstrapContext"

workManager="#workManager"

transactionManager="#transactionManager">

<jencks:connectionTrackerid="connectionTracker"

geronimoTransactionManager="#transactionManager"

>

<jencks:poolingSupportid="poolingSupport"

allConnectionsEqual="false"/>

<jencks:connectionManagerid="connectionManager"

containerManagedSecurity="false"transaction="xa"

transactionManager="#transactionManager"

poolingSupport="#poolingSupport"

connectionTracker="#connectionTracker">

<beans>

Inordertoleveragetransactionswithasynchronousmessageexchanges,theJCAflowmustbeused.ThisiswhatwedobyincludingjcaFlowinsidetheflowselement.WhileweconfiguretheJBIcontainer,ifwesettheautoEnlistInTransactionflagtotrue,eachtimeaJBIexchangeissent,itwillbeenlistedinthecurrenttransaction.

DeployandRuntheSampleBeforerunninganysamplesinthischapter,ifyouhaven'tdoneitbeforeeditexamples.PROPERTIES(providedalongwiththecodedownloadforthischapter)andchangethepathstheretomatchyourdevelopmentenvironment.

Nowtobuildtheentiresample,itiseasiertochangedirectorytothetop-levelfolderandexecutethebuild.xmlfileprovidedthere:

cdch17\01_Transactions\InOnlyAsync

ant

Thiswillbuildtheentirecodebaseforthetransactiondemonstration.NowweneedtoopenanothercommandpromptandstartServiceMixintheembeddedmode,asfollows:

cdch17\01_Transactions\InOnlyAsync

antrun

IncaseyouwanttorunthetestasaJUnittestcase,executethefollowingcode:

anttest

Attheendoftherun,wewillattempttoclosetheJBIcontainerbydestroyingthecontext.AswearestartingtheServiceMixinembeddedmodeitwillgenerateexceptionsin

theconsole.Theseerrorscanbeignored.Insteadyoucanconcentrateontheapplicationloggingwhichisreproducedhere:

[junit]JmsInOnlyAsyncTest.testJmsInOnlySync-

Start...

[junit]JmsInOnlyAsyncTest.testJmsInOnlySync-

TransactionCommitted.

[junit]INFO-MessageList-Waitingformessage

toarrive

[junit]INFO-MessageList-Endofwaitfor1001

millis

[junit]JmsInOnlyAsyncTest.testJmsInOnlySync-

End.

[junit]JmsInOnlyAsyncTest.tearDown...

[junit]ClosingdowntheSpring

ApplicationContext

WecanseethattheMessageListwaitsformessageswhichitreceivesattheendof1001milliseconds.ThefollowingscreenshotshowstheESBconsole:

SampledemonstratingSecurityThesecurityinServiceMixcanbeconfiguredatmultiple

levelsandatmultiplelayers.Inthissectionwewilldemonstrateasimplesecurityconfigurationfortheservicemix-httpcomponent.WewillconfigureHTTPbasicauthenticationandasperthat,whenaclienttriestoaccessaresourcemarkedasprotectedintheserver,theserverpromptsforausernameandpasswordcombination.Thisisfollowedbythebrowserpromptingwithausernameandpasswordentryformwheretheusercanentertherelevantinformationandsubmit.

SampleUseCaseThesetupofcomponentsforthesampleusecaseisshowninthefollowingfigure:

Thesecuritysampleusecasewillhaveservicemix-httpconfiguredintheconsumerrole,listeningforHTTPtransportforaparticularport.WethenconfigureanEchoservicecomponentasthetargetServicefortheaboveHTTPconsumer.Whendoingso,wealsotellthattheHTTPbasicauthenticationhastobeapplied.AnexternalHTTPclientprovidedcanbeusedtotargetmessagestotheHTTPconsumer.Whentheexternalclientsendsrequests,theserverpromptsforausernameandpasswordcombination.Thisisfollowedbythebrowserpromptingwithausernameandpasswordentryform.

ConfigureBasicAuthorizationin

servicemix-http

Wewilluseasetofpropertiesfileandconfigurationfilesasshownabove,forsettingupthesecuritysample.

Theservicemix.xmlfilewillhostthemainsecurityconfigurationsasshownhere:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:http="http://servicemix.apache.org/http/1.0"

xmlns:soap="http://servicemix.apache.org/soap/1.0"

xmlns:test="http://binildas.com/esb/servicemix/security">

<importresource="classpath:activemq.xml">

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:security.xml">

<classpath>

<location>.<location>

</classpath>

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<sm:systemProperties>

<propertyname="properties">

<map>

<entrykey="java.security.auth.login.config">

<bean

class="org.springframework.util.ResourceUtils"

factory-method="getFile">

<constructor-argvalue="classpath:basiclogin.

properties">

<bean>

</entry>

</map>

</property>

</sm:systemProperties>

<sm:containerid="jbi"rootDir="./wdir">

<sm:broker>

<sm:securedBroker>

<sm:authorizationMap>

<sm:authorizationMap>

<sm:authorizationEntries>

<sm:authorizationEntryservice=":"

roles="superuser"/>

<sm:authorizationEntryservice="test:echo"

roles="secureuser">

<sm:authorizationEntries>

</sm:authorizationMap>

</sm:authorizationMap>

</sm:securedBroker>

</sm:broker>

<sm:activationSpecs>

<sm:activationSpecid="http">

<sm:component>

<http:component>

<http:endpoints>

<http:endpointservice="test:httpConsumer"

endpoint="httpConsumer"targetService="test:echo"

role="consumer"

locationURI="http://localhost:8192/Service/"

authMethod="basic"defaultMep="http://www.w3.org/

2004/08/wsdl/in-out">

</http:endpoint>

</http:endpoints>

</http:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="echo"

service="test:echo">

<sm:component>

<beanclass="org.apache.servicemix.components.

util.EchoComponent">

<sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

Here,forthehttp:endpointelementyoudefinetheHTTPbasicauthenticationbysettingauthMethod="basic".

Wecanalsoplug-inauthorizationintheconfiguration.Forthis,wefirstdefineasecuredbroker(sm:broker)whichcanmatchthebasicHTTPauthenticateduseragainstanAccessControlList(ACL).Toplug-intheACL,wefirstsetthesystempropertieswithkey"java.security.auth.login.config"andvaluepointingtobasiclogin.properties.basiclogin.propertiesisshowninthefollowingcode:

servicemix-domain

{

org.apache.servicemix.jbi.security.login.PropertiesLoginModule

required

debug=true

org.apache.servicemix.security.properties.user="basicusers.

properties"

org.apache.servicemix.security.properties.group="basicgroups.

properties";

};

Thebasicgroups.propertiesdefinesvariousgroupsandmapswhichallusersbelongtowhichallgroups.Thebasicgroups.propertiesisshownhere:

superuser=manager

secureuser=binil

Now,theusercredentialsarestoredinthebasicusers.propertiesandareshownhere:

system=manager

binil=binil

user1=user1

Thesecuredbrokerputstheauthorizationrulesasfollows:

Asadefaultpolicy,letonlythe"superuser"rolebeallowedtoaccessJBIendpoints.

<sm:authorizationEntryservice=":"

roles="superuser"/>

Letuserswithrole"secureuser"beauthorizedtoaccesstest:echoservice.

<sm:authorizationEntryservice="test:echo"

roles="secureuser"/>

DeployandRuntheSampleTobuildtheentiresample,changedirectorytotheBasicHttpfolderandexecutethebuild.xmlfileprovidedasfollows:

cdch17\02_Security\BasicHttp

ant

NowbringtheServiceMixserverupbyexecutingthefollowingcommand:

%SERVICEMIX_HOME%\bin\servicemixservicemix.xml

OnceServiceMixisup,executeClient.htmlfileprovidedagaininthesamefolder,andclickthesendbutton.Thebrowserwillpromptfortheusernameandpasswordentryformwhereyoucanenterthecredentialsbinilandbinilbelongingtothesecureusergrouptoaccesstheservice.

Ifyoutrytoaccesstheservicewithadifferentcredential(forwhichtheACLpermissionisnotgranted),theservicewillnotbeaccessibleforyou.

SampleDemonstratingClusteringThissectionwilldemonstratetheclusteringfeaturesprovidedbyServiceMixwhichwediscussedearlierwiththehelpoftherunningsamples.

SampleUseCaseThesamplescenarioweuseforclusteringwillconsistofthreeServiceMixinstancesconfiguredinacluster.Forthesakeofsimplicity,allthreeinstanceswillcurrentlyruninasinglephysicalnode,henceweareusingthe"localhost"astheserverIPeverywhere.However,itispossibletodistributetheseinstancesintodifferentphysicalnodesinwhichcasewemayhavetousetheIPaddressofthesenodestoformthecluster.

Thefollowingfigureshowstheclustersetup.Here,wehavethreedifferentServiceMixinstances.Sinceinclustermode,alltheServiceMixinstancesmusthaveauniquenameinthewholecluster.Wewillnametheinstanceswithdifferentnamesnamelyadmin,managed1,andmanaged2.OneoftheseServiceMixinstancesalsomanagesaJMSconnectionbroker,andhencewehavearbitrarilynamedthatinstancewiththename"admin".

TheJBIservicescanbedeployedintoanyoftheServiceMix

instancesinthiscluster.Todeployaserviceintothecluster,wewilldeploythoseservicesintoall(ormany)instancesintothecluster.Whenwedoso,allthecontainersintheclusterarenotifiedofthedeployment.NowtheclustercanadministerroutingorloadbalancingpolicieswhenitreceivesclientrequestsbyautomaticallyroutingMessageExchange(s)betweenthemembersofthecluster.Suchserviceswhichwedeployacrossclustersarecalledclusteredservices.WecanalsodeployservicesintoasingleinstanceoftheJBIcontainerintheclusterinwhichcasewecalltheserviceapinnedservice.

Foraclusteredservice,evenifoneoftheServiceMixinstanceshostingtheserviceisdowntheserviceisstillupsincethereareotherclusterinstancestoservetherequest.Howeverforapinnedservicewehavetomakesurethattheserverinstancetowhichtheserviceispinnedshouldbeup,otherwisetheservicewillceasetoserve.

Forthesample(refertothepreviousfigure)wewillmakeuseofbothclusteredandpinnedservices.Asshowninfigure,receiver3isaclusteredservicesinceitisdeployedinboththeinstancesofthecluster.receiver1andreceiver2arepinnedservicessincetheyaredeployedtomanaged1andmanaged2instancesalone,respectively.TheexternalJMSclientwilltargetthemessagestoalltheabovethreeservices.Wecanseethatformessagestargetedtoreceiver1andreceiver2,theyarealwaysroutedtomanaged1andmanaged2serverinstancesrespectively.However,formessagestargetedtoreceiver3theclusterwillloadbalancetherequeststoanyoftheserversinthecluster.Ifbyanychancewebringdownanyofthe

managedservers,thenthepinnedservicesinthatinstancewillnolongerbeavailable,butallthesubsequentrequestsfortheclusteredservicewillthenonwardsberoutedtotheotherinstance(s)oftheserverintheclusteralone.

Thevariousartifactsusedfortheclusteringdemonstrationarearrangedwithindifferentsubfoldersasshowninthedirectorystructureinthefollowingfigure:

ConfigureServiceMixClusterForeachoftheServiceMixserverinstancesparticipatinginthecluster,wehavedifferentserverconfigurationfiles,andlet

uslookatthemonebyone:

Theadminserverconfigurationisincludedinch17\03_Clustering\admin\

servicemixadmin.xml,whichisshowninthefollowingcode.

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:amq="http://activemq.org/config/1.0"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:jms="http://servicemix.apache.org/jms/1.0"

xmlns:foo="http://servicemix.org/demo/">

<beanid="propertyConfigurer"

class="org.springframework.beans.factory.config.

PropertyPlaceholderConfigurer">

<propertyname="location"

value="classpath:servicemix.properties">

<bean>

<importresource="classpath:jmx.xml">

<importresource="classpath:jndi.xml">

<importresource="classpath:security.xml">

<importresource="classpath:tx.xml">

<importresource="classpath:activemq.xml"/>

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<sm:containerid="jbi"name="admin"

flowName="jms?jmsURL=tcp:/localhost:61616"

useMBeanServer="true"createMBeanServer="true"

rmiPort="1111">

<sm:activationSpecs>

<sm:activationSpec>

<sm:component>

<jms:component>

<jms:endpoints>

<jms:endpointservice="test:MyConsumerService"

endpoint="myConsumer"role="consumer"

soap="false"targetService="foo:recipients"

defaultMep="http://www.w3.org/2004/

08/wsdl/in-only"destinationStyle="queue"

jmsProviderDestinationName="queue/A"

connectionFactory="#connectionFactory">

<jms:endpoints>

</jms:component>

</sm:component>

</sm:activationSpec>

<sm:activationSpecid="servicemix-eip">

<sm:component>

<eip:component>

<eip:endpoints>

<eip:static-recipient-list

service="foo:recipients"endpoint="endpoint">

<eip:recipients>

<eip:exchange-targetservice="foo:receiver1">

<eip:exchange-targetservice="foo:receiver2">

<eip:exchange-targetservice="foo:receiver3">

<eip:recipients>

</eip:static-recipient-list>

</eip:endpoints>

</eip:component>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

<beanid="broker"

class="org.apache.activemq.xbean.BrokerFactoryBean">

<propertyname="config"

value="classpath:activemq.xml">

<bean>

<beanid="jmsFactory"

class="org.apache.activemq.pool.PooledConnectionFactory">

<propertyname="connectionFactory">

<refbean="connectionFactory">

<property>

</bean>

<beanid="connectionFactory"

class="org.apache.activemq.ActiveMQConnectionFactory">

<propertyname="brokerURL"

value="tcp://localhost:61616">

<bean>

</beans>

HerewehaveaJMSconsumerthroughwhichtheexternalJMSclientcansendmessagestotheNMR.ThenwehaveconfiguredJMSbrokertobelisteningatlocalhost:61616.Moreover,wehavealsosettheflowtobeoftypeJMSbysettingflowName="jms?jmsURL=tcp://localhost:61616".

Thefirstmanagedserverconfigurationisincludedinch17\03_Clustering\managed1\

servicemixmanaged1.xml,whichislistedinthefollowingcode:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:amq="http://activemq.org/config/1.0"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:foo="http://servicemix.org/demo/">

<classpath>

<location>.</location>

<location>./build</location>

</classpath>

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<sm:containerid="jbi"name="managed1"

flowName="jms?jmsURL=tcp:/localhost:61616"

useMBeanServer="true"createMBeanServer="true">

<sm:activationSpecs>

<sm:activationSpeccomponentName="receiver1"

service="foo:receiver1">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="managed1.MyReceiver">

<propertyname="name">

<value>1</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver3"

service="foo:receiver3">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="managed1.MyReceiver">

<propertyname="name">

<value>3</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

Herewesetname="managed1"andalsosetflowName="jms?

jmsURL=tcp://localhost:61616".Thenthismanagedserveralsowillformapartofthesameclusterjoinedbytheadminserver.Thenwedeployreceiver1and

receiver3servicestothisserver.

Thesecondmanagedserverconfigurationisincludedinch17\03_Clustering\managed2\

servicemixmanaged2.xml,whichislistedasfollows:

<?xmlversion="1.0"encoding="UTF-8"?>

<beans

xmlns:sm="http://servicemix.apache.org/config/1.0"

xmlns:amq="http://activemq.org/config/1.0"

xmlns:eip="http://servicemix.apache.org/eip/1.0"

xmlns:foo="http://servicemix.org/demo/">

<classpath>

<location>.</location>

<location>./build</location>

</classpath>

<beanid="jndi"

class="org.apache.xbean.spring.jndi.

SpringInitialContextFactory"

factory-method="makeInitialContext"

singleton="true">

<sm:containerid="jbi"name="managed2"

flowName="jms?jmsURL=tcp:/localhost:61616"

useMBeanServer="true"createMBeanServer="true"

rmiPort="1111">

<sm:activationSpecs>

<sm:activationSpeccomponentName="receiver3"

service="foo:receiver3">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="managed2.MyReceiver">

<propertyname="name">

<value>3</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

<sm:activationSpeccomponentName="receiver2"

service="foo:receiver2">

<sm:component>

<beanxmlns="http://xbean.org/schemas/spring/1.0"

class="managed2.MyReceiver">

<propertyname="name">

<value>2</value>

</property>

</bean>

</sm:component>

</sm:activationSpec>

</sm:activationSpecs>

</sm:container>

</beans>

Herethemaindifferenceisthatwesetname="managed2".MoreoverwesetflowName="jms?jmsURL=tcp://localhost:61616"sothatthismanagedservertoowillformapartofthesameclusterjoinedbytheadminandpreviousmanagedserver.Thenwedeployreceiver2andreceiver3servicestothisserver.

Soinanutshell,receiver1andreceiver2arepinnedserviceswhereasreceiver3isaclusteredservice.

DeployandrunthesampleTobuildtheentiresample,itiseasiertochangedirectorytothetop-levelfolderandexecutethebuild.xmlfileprovidedthere:

cdch17\03_Clustering

ant

Thiswillbuildtheentirecodebasefortheclusteringdemonstration.Nowweneedtotakethreedifferentcommandpromptsandbringupalltheserverinstancesinthecluster,inthesameorderasshownasfollows:

cdch17\03_Clustering\admin

%SERVICEMIX_HOME%\bin\servicemix

servicemixadmin.xml

cdch17\03_Clustering\managed1

%SERVICEMIX_HOME%\bin\servicemix

servicemixmanaged1.xml

cdch17\03_Clustering\managed2

%SERVICEMIX_HOME%\bin\servicemix

servicemixmanaged2.xml

Theclustershouldbeupbynow.Nowtotesttheclustersetup,inadifferentcommandpromptexecutethefollowing:

cdch17\03_Clustering

antrun

Keepwatchingontheserver-sideconsoleprintouts,especiallytheconsoleofthemanaged1andmanaged2servers.Executeantrunacoupleoftimesandunderstandhowtheclusterloadbalancesrequeststargetedtothedifferentservices.

Themanaged1serverconsoleisshowninthefollowingscreenshot:

Themanaged2serverconsoleisshowninthefollowingscreeenshot:

Wecanseethattherequestroutedtoreceiver3(whichisaclusteredservice)isloadbalancedwhereastherequestsroutedtoreceiver1andreceiver2(whicharepinnedservices)arealwaysservedbytheirrespectivepinnedservers.

Youmayalsowanttokilloneofthemanagedserversandtrytheeffectofthatonnewincomingrequests.Youcanlaterbringthisdeadserverbacktojointheclusterwithoutdisturbingtheclustersetup.

SampledemonstratingJMX

TodemonstrateJMXinServiceMix,wewillusethesamesampleweusedforChapter9(PojoBindingUsingJsr181).Thesamplech09\Jsr181BindPojoisrepeatedinthischapterandiskeptinfolderch17\04_JMX.

EnableJMXinServiceMixApplicationServiceMixusesthefollowingparameterforenablingJMX:

ThedefaultnamingPort:1099.

Thedefaultcontainername:jmxrmi.

TheJMXServiceURL:service:jmx:rmi:///jndi/rmi://localhost:10

99/jmxrmi.

ThesearethedefaultsettingsforServiceMixversion3.x.Forversion2.x,JMXServiceURLalonechangesto:service:jmx:rmi:///jndi/rmi://localhost:10

99/defaultJBIJMX.

Theabovevaluesareconfiguredthrough%SERVICEMIX_HOME%\conf\jmx.xml.Tostartsimple,editthejmx.xmlfiletodisablethesecurityfeature.Thiscanbedonebyfirstsearchingfor"CommentthefollowinglinestodisableJAASauthenticationfor

jmx"andthencommentingthesucceedinglines.

Now,bringServiceMixup.ThiscanbedonebytryingoutanyofthesamplesinthepreviouschaptersoryoucanusetheJMXsampleprovidedwiththischapter.Todothat,changedirectorytoch17\04_JMXwhichcontainsatop-levelbuild.xmlfile.Executeantthere.

cdch17\04_JMX

ant

Now,bringuptheServiceMixcontainerbyexecutingtheservicemix.xmlfilecontainedinthesamefolder.

%SERVICEMIX_HOME%/bin/servicemixservicemix.xml

InitializeJMXConsole—MC4JYoucanuseanyofyourfavoriteJMXtoolstocontroltheServiceMixapplication.TheJava-2Platform,StandardEdition(J2SE)5.0releaseonwardsincludesaJMXmonitoringtool,JConsole.TobringJConsoleup,executethefollowingcommands:

cd%JAVA_HOME%\bin

jconsole

ForourdemonstrationwewilluseMC4JprovidedbySourceForge.MC4JisthemanagementsoftwareforJ2EEapplicationserversandotherJavaapplications.ItutilizestheJMXspecificationtoconnecttoandintrospecttothe

informationwithinthesupportedserversandapplications.Itprovidestheabilitytobrowsetheexistingmanagedbeans(MBeans),updateconfigurations,monitoroperations,andexecutetasks.

Clickonthe"MC4JConsole1.2b9.exe"filefoundinthetop-leveldirectoryoftheMC4JinstallationtobringuptheMC4Jwindow.ThisMC4Jwindowisshowninthefollowingscreenshot:

SelectManagement|CreateServerConnection...fromthemenu.ThiswillstartMyWizard.AconnectiontoServiceMixcanbecreatedusingthewizard.

Inthewizard,enterthefollowingintothetextboxesandpull-downmenus:

SelectyourserverconnectiontypeasJSR160.

TheNametextboxisfilledwithanyname,forexample,ServiceMix.

SelectServerURLasservice:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi.

AcceptthedefaultsfortherestofthefieldsinthewizardandclicktheNext>button.NowclickFinishinthenextwindow.ThiswillmakeaconnectiontoServiceMix!

Clickonorg.apache.servicemix(1).ThecomponentsofthePOJObindingexamplewillbeshown.Right-clickonacomponentandselectAvailabledashboards...|Basic

MBeanViewtoseetheJMXinformationavailableasshowninthefollowingscreenshot:

RetrieveWSDLthroughJMXAttimeswhenyoutryoutyoursamplesinServiceMixyoumayfeelthatsomethingisnotworkingproperlyorsomeinformationretrievedisnotasperyourexpectation.InsuchscenariositmakessensetomakeuseofaJMXconsoleandlookintothecomponentconfigurations.Letusdoasimilaractivitynow.

InthePOJObindingsampleyouhavealreadywiredtheserviceinterfaceandserviceimplementationasfollows:

<jsr181:endpointannotations="none"

service="test:helloService"

serviceInterface="samples.HelloServiceBI">

<jsr181:pojo>

<beanclass="samples.HelloServicePojo">

</bean>

</jsr181:pojo>

</jsr181:endpoint>

LetusnowloadtheWSDLgeneratedbytheJBIbusbyclickingontheloadWSDLbutton.YoumayhavetounchecktheViewasHTMLcheckboxtomaketheWSDLvisible,whichisshowninthefollowingfigure:

SummaryIhopeyouhaveenjoyedthislastchapter.Thesamplesdemonstratedhere,especiallytheusageoftheJMXtooltolookintotheartifactsinsidethebuswillbehighlyusefulwhen

yourunyourowncomponentsinsidetheServiceMixJBIbus.

Ifyouhavegonethroughallthepreviouschaptersalsointhistext,bynowyoushouldhave"handson"knowledgeofwhatanESBisandwhatJBIhastodoindefiningESB-basedarchitectures.ThiswillgiveyouanedgeoveryourpeersinunderstandingESBandinpreparingyourselvestoleverageESBtosolveyourintegrationproblems.

InmyentirecareerIhaveinteractedwithalotofpeoplewhotalkandwritealotonESBinwhitepapers,buttheynevergavemeanycodetoplayaroundwith.ItisinthiscontextIdecidedtospendafewchaptersonESBwithcode.IhopeyouenjoyedreadingjustasIenjoyedwritingit.