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SchoolofComputerScience

ArchitecturalPatterns/Styles

CharlieGarrod MichaelHilton

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Administrivia

• Homework6checkpoint– MondayDec4th

• FinalExamReview:Dec13th,2-4pmWean5409• FinalExam:Dec15th,5:30-8:30pmWean7500

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LastTime:

• DesignPatterns

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ARCHITECTURALPATTERNS/STYLES

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DesignPatterns

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ArchitecturalStyles

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ArchitecturalStyles

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ArchitecturalStylesvsDesignPatterns

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MonolithicApplication

+Simpletostart+Simpletodeploy+Fasttimetofirstfeature- Difficultfornewdeveloperstocomeuptospeed- Continuousdeploymentisdifficult- Scalingcanbedifficult- Candevolveinto“bigballofmud”

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Layers

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Layers

• Context:– Alargesystemthatrequiresdecomposition

• Problem:– Lowseparationofconcerns.– Partsofsystemarenotinterchangeable– Lackofgroupedcomponentshurtsunderstandabilityandmaintainability– Lackofboundariesmakestaskingdifficult

• Solution:– Definelayersofabstraction– Specifyservicesbetweenboundaries

• Beware:– Antipattern:Sinkhole– Antipattern:Lasagna

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Pipeandfilter

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Pipeandfilter

• Context:– Processingdatastream

• Problem:– Needtoprocessortransformastreamofdata– Non-adjacentstepsdon’tshareinformation– Needtoreusecertainstepsintheprocess

• Solution:– Eachfiltertransformsthedata,thenmovesitontothenextstep

• Beware:– ErrorHandling– Datatransformationoverhead

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Blackboard

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Blackboard

• Context:– Animmaturedomainwherenoclosedapproachisknowntobefeasible

• Problem:– Acompletesearchofsolutionspaceisnotfeasable– Multiplealgorithmspossiblefordifferentsubtasks– Somealgorithmsworkontheoutputofothers– Uncertaindataandaprox solutionsareinvolved

• Solution:– Independentprogramsworkingcooperativelyoncommondata– Inspectandupdatedata

• Beware:– Difficulttotest– Difficultestablishingagoodcontrolstrategy

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Model-View-Controller

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Model-View-Controller

• Context:– InteractiveapplicationswithaflexibleHuman-Computerinterface

• Problem:– Howtodevelopanapplicationnotdependentoninterface– Needabilityforapplicationtosupportdifferentinterfaces– Allowsimultaneousdevelopment

• Solution:– Model– View– Controllerdivision

• Beware:– Codenavigability– Increasedcomplexity

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Broker

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Broker

• Context:– Decoupledcomponentsinteractthroughremoteserviceinvocations

• Problem:– Scalingforlargescalesystems– Componentsshouldbedecoupledanddistributed

• Solution:– Brokersmediatebetweenclientsandservers

• Beware:– Lessefficient– Lowerfaulttolerance

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Microkernel

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Microkernel

• Context:– Thedevelopmentofseveralapplicationsthatusesimilarinterfaceson

samecore

• Problem:– Shouldcopewithcontinuoushardwareandsoftwareevolution– Platformshouldbeportable,extensibleandadaptable

• Solution:– Encapsulatefundamentalservicesofyourapplicationplatformina

microkernel– Otherfunctionalityprovidedbyinternalservers

• Beware:– Complexityofdesignandimplementation

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Event-drivenarchitecture

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Event-drivenarchitecture

• Context:– Buildingalooselycoupled,moreresponsivesystem

• Problem:– Buildasystemthatreactstoeventsintheworldaroundit– Onlyhavetodecidewhattodo,notwhentodoit

• Solution:– Eventcreators,managers,andconsumers

• Beware:– Securityrisks– Increasedcomplexity

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Peer-to-peer

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Peer-to-peer

• Context:– Asystemwhereeachnodehasthesamecapabilitiesandresponsibilities

• Problem:– Asituationwhereitisnotfeasibletoknowaheadoftimewhichnodes

willbeservers– Largeamountsofdataneedtobesenttransmitted

• Solution:– Decentralizedcomputing– Highlyrobustinthefaceofnodefailure– Highlyscalable

• Beware:– Noservertomanagedata– Noalwaysusedforlegalpurposes

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Service-orientedarchitecture

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Service-orientedarchitecture

• Context:– Servicesareprovidedtoothercomponentsoveranetwork

• Problem:– Buildingadistributedsystem– Exposeaservicenoobjects

• Solution:– Eachserviceshould:

• Representabusinessactivitywithaspecificoutcome• Beself-contained• Ablack-boxforitsconsumers• Mayconsistofunderlyingservices

• Beware:– Highinvestmentcost

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Exercise:

• Styles:– Monolith– Layers– PipeandFilter– Blackboard– MVC– Broker– Peer-to-peer– Microkernel– Event-driven– Service-oriented

• Application– Onlinebankingapplication– APIforthirdpartytoolstoget

bankinginformation– Compiler– OpticalCharacterrecognition– VRcontentdeliverysystem– VRgame– Insuranceclaimprocessing

system