J2EEBestPractices webinar

Push your development furtherSun™TechDays

1

J2EE Best Practices using a Real-life Example.Carol McDonaldTechnology [email protected]

Sun™ Tech Days


2

eBay Architecture: How to Go…

Microsoft IIS

eBayISAPI.dll

MSXML

… to here?From there…J2EE™ Container

Web ContainerPresentation Tier

EJB™ Container

Business Tier

Integration Tier

Services

Con

figur

atio

n

Logg

ing

Secu

rity

Monolithic Proprietary

Layered Loosely coupled Modular Standards based


3

What Is Needed…

Learning the technology is not enough

Industry best practices Proven solutions How to avoid bad practices?


4

Core J2EE™ Patterns

Collection of best practices and Patterns for for J2EE™ architecture

Also J2EE™ architecture bad practices and refactorings

Based on Sun Java Center Services experience

Proven solutions Reuse design Robust and scalable architecture Improve quality Flexibility and maintainability

Create a common vocabulary


5

JavaTM BluePrints Program

http://java.sun.com/blueprints JavaTM Technology Series

books– Designing Enterprise Applications

with the J2EE Platform, 2nd Edition● Covers J2EETM 1.3 platform features

– Designing Web Services with the J2EE Platform (available soon)

Sample applications– Java Pet Store Demo– Java Adventure Builder Demo– Concrete code for the BluePrints

guidelines – Starting points for your applications


6

Agenda

Web Tier best practices EJB Tier best practices Persistence Options Container Managed Persistence

J2EE Performance JMS Best Practices (depending on the time)


7

Some Web TierBest Practicesand Patterns


8

Layering

EJB Session Beans

Web Tier or Client

Data Transfer Objectsi.e. Business Data Values

Business Logic LayerService Layer

Domain LayerPersistent Entities

Presentation Layer

Network

EntityEJBs


9

Rationale for Layers

More flexible, extensible: Presentation Layers

Frequent changes, design to be flexible Business Services

Implement “use-cases” Public Service interface Interface should remain valid for changes in

presentation and data store Data Layers

Fewer changes, designed to optimize data access


10

Model View Controller

Client

Problem Domain Services

Enterprise Resources

Controller View

Persistence Layer

Model Layer

Presentation Layer

Thin Browser

HTTP Request HTML Page

Model = business data and rules, shared by all clients Controller defines the application behaviour, interprets user

actions and maps them into actions performed on the model View = renders the contents of the Model


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Model View Controller

ModelView

Controller

Client Web EJB Tier

Request

ForwardEvent

Data

Response

ServletServlet

JSPJSP BeanBean

BusinessEvent

MVC Pattern

Model

✗Separate:●Model data●Control●Presentation of view


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Service to Worker

CommandFactory

Front Controller

Dispatcher

CommandHelper

1. Request

3. Parse Request

2. Common logic

5. Create

6. Execute

8. Dispatch7. Business logic

4. Get cmd

ViewHelperDataBean

View

Client

Servlet

JSPJava™ Objects

10. Response

9. Get Data

= MVC Pattern with more detail


13

Use an MVC Framework

Use Struts, JSF, or Sun Java Studio ... application framework

Frameworks provide a skeleton which you can extend Faster, easier development of Request processing Response generation

Improve Design Modularity Maintainability


14

Struts MVC Framework

Model

Action

Action

Action

Action

ActionServlet(Controller)

View 1

View 2

Struts-config.xml........................

1 23

4

5

Form Bean


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Struts and Core J2EE Patterns

Client

Action Servlet Action

ActionForward

ActionFormJSP View

Front Controller Model

View HelperView

Action Mapping

(xml)

BusinessService

Command

Dispatcher

Response

Request

Uses


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Ebay.com: Presentation Tier

Request

Response

Client

BusinessServiceCommand

Request Handler

InterceptingFilter

Front Controller

Navigator Dispatcher

Navigation and Dispatch

View Processor

TransformerHelper

InterceptingFilter

ViewProcessor

XML

XSL Core J2EE

Pattern

Strategy

?


17

Business Delegate

Client independent from ejb tier

Ejb details hidden

Mock objects can be used to test client w/o ejb tier


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Ebay.com: Presentation Tier

Request

Response

Client

BusinessServiceCommand

Request Handler

InterceptingFilter

Front Controller

Navigator Dispatcher

Navigation and Dispatch

View Processor

TransformerHelper

InterceptingFilter

ViewProcessor

Business Delegate

Service Locator

XML

XSL Core J2EE

Pattern

Strategy

Service Interface


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Cache for Performance

Some things can be cached and shared, use a singleton: InitialContext object (JNDI object used for lookups) Anything retrieved from JNDI, EJB Home interfaces Repeated lookups can be expensive! Use Service Locator

Pattern

Some things are user specific, cached in session: Cache search results when you are only displaying a few

at a time (static data) Value List Pattern


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Service Locator Pattern

Use the Service Locator Pattern toCache references obtained by JNDI lookups (ejb references, datasources, jms connection)

Repeated lookups can be expensive!

DON'T DO

EJBClient

EJBClient

JMSClient

JDBCClient

EJBClient

EJBClient

ServiceLocator

JMSClient

JDBCClient

JNDI

JNDI


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ServiceLocator code 01 public class ServiceLocator {02 private InitialContext ic;03 private Map cache;04 private static ServiceLocator me;0506 private ServiceLocator() {07 ic = new InitialContext();08 cache =new HashMap();09 }10 public static ServiceLocator getInstance() {11 if (me == null) {12 me = new ServiceLocator();13 }14 return me;15 }


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ServiceLocator code 01 public EJBHome getRemoteHome(String jndiHomeName, Class className){02 EJBHome home = null;03 if (cache.containsKey(jndiHomeName)) {04 home = (EJBHome) cache.get(jndiHomeName);05 } else { 06 Object objref = ic.lookup(jndiHomeName);07 Object obj = PortableRemoteObject.narrow(objref, className);08 home = (EJBHome)obj;09 cache.put(jndiHomeName, home);10 }11 return home;12 }15


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Client code 01 ServiceLocator serviceLocator = 02 ServiceLocator.getInstance(); 03 try { 04 ProjectHome projectHome =(ProjectHome) 05 serviceLocator.getHome(“ProjectHome.class”); . . .


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Tips for Servlet Performance

Don't store a lot of data in the HTTP Session

Remove servlet sessions when they are no longer needed: In logoff call session.invalidate()


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Servlet Tips

DO use high performance J2EE design patterns MVC, Service Locator

DON’T hold resources – explicitly free them


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Tips for JSPs

Avoid scriptlets in JSP Use JSTL (JSP 2.0 Standard Tag Libraries): <c:forEach var="item" values="${cart}">

Pass data to JSP in Servlet request object not session

If JSP does not use the HTTP session Use <%page session="false"%> to prevent

HTTP Sessions from being automatically created


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Some EJB Tier Best Practicesand Patterns


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Do you need EJBs? Do you need declarative

transactional support? Do you need to distribute your

business logic? Do you need JMS, JAX-RPC, RMI? Do you need to support multiple

client types? Do you need method-level security

on your objects? Do you need Clustering for Scalability?


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Architecting Applications

Functional requirements captured via use-cases

Use-cases implemented using MVC & Command design patterns

Implement Business Logic as Services Verbs in use cases help define services Noun in use cases help define business data

objects

ebay Case Study


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ebay Use case realization

View Items

Any User

View Itemsby category

Any user can view auction items by category

ebay Case Study


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AssembleData

Use caseBiz logic

Convert to Biz Command

CentralizeRequest Hndlg

View Items Design Requirements

Retrieve Data by category

ebay Case Study


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Action Command

Front Controller

SessionFacade

BusinessDelegate

View Items Design

ServiceLocator

TransferObject

AssemblerTransferObject

Value ListHandler

Data AccessObject

ebay Case Study


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WEB Tier

Presentation Business Logic &Messaging Fabric

Data Integration& Persistence

Core Application Design Patterns

FRONTCONTROLLER VIEW

COMMANDobject

Request Response

MODEL

DATATRANSFER

OBJECT

BUSINESSSERVICEFACADE

Value List HandlerDATA

ACCESSOBJECT

DATATRANSFER

OBJECT

SessionEJB

Servlet

JSP

Java™ Objects

Session EJB

Ebay Case Study


34

Data Transfer Object

DON'T DOtoo much network traffic

DOReduce network trafficwith Data Transfer Object

ClientObject EJB

Before

ClientObject

EJBItem InfoData Transfer Object

After

GetItemInfo()

GetCity()

GetState()

GetZipCode()

GetCity()

GetState()

GetZipCode()

Networkboundary

Networkboundary

Return DTO

A Data Transfer Object encapsulates a set of data values to return to the client in one network transfer


35

WEB Tier





COMMANDobject

Request Response

MODEL

DATATRANSFER

OBJECT



ACCESSOBJECT

DATATRANSFER

OBJECT

SessionEJB

Servlet

JSP

Java™ Objects

Session EJB


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Data Access Object

BusinessObject DataAccessObject DataSource

TransferObject

Uses Encapsulates

creates/uses

obtains/modifies

Use Data Access Objects to encapsulate data-access logic

-provides a simplified interface for performing complex JDBC operations

-allows decoupling of data-access optimizations

Use DAO for read-only tabular access to a large set of data, when query results are large and short-lived


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EJB Tier patternsData Access Object (DAO)

public class FacadeEJB implements SessionBean { protected EbayDAO dao; public void ejbCreate() { try { dao = EbayDAOFactory.getDAO(); } catch (EbayDAOSysException se) { throw new EJBException(se.getMessage()); } } … public ListChunk getItems(String categoryId, int startIndex, int count, Locale locale) { try { return dao.getItems(categoryId, startIndex, count, locale); } catch (EbayDAOSysException se) { throw new EJBException(se.getMessage()); } } …. }


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WEB Tier





COMMANDobject

Request Response

MODEL

DATATRANSFER

OBJECT



ACCESSOBJECT

DATATRANSFER

OBJECT

SessionEJB

Servlet

JSP

Java™ Objects

Session EJB


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Value List Handler For querying, filtering, and

displaying large amounts of data: Value List Handler handles

the search, can cache results and provides a traversable result set

Client ValueListHandler<<List>>

ValueList TransferObject

DataAccessObject

InterfaceValueListIterator

+GetSize():int+getCurrentElement():Object+getPreviousElements(count:int):List+getNextElements(count:int):List+resetIndex():void


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Example Caching Results

Create

Execute Search

Get Next

Get Previous

Get Current

Get Size

Return Sub-list

Return Sub-list

Return Value Object

Return Size

Execute Search

Return Value List

Get Sub-list

Get Sub-list

Get Current

Get Size

Create

Client

ValueListHandler

DataAccessObject

ValueListValueListiterator

Return Sub List

Stateful Session


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Returning Search Results Options

ValueList Handler as a Stateful Session EJB caches search results, and returns sub list

ValueList Handler as Stateless Session EJB: Select * FROM item WHERE id=?

LIMIT [count] OFFSET [startIndex]

Instead of Value list could use JDBC 2.0 scrollable ResultSet but keeps JDBC data source connection open ! (J2SE 1.5 will have disconnected scrollable ResultSet)


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Stateless Example

Create

Execute Search (index, count) Execute Search (index, count)

Return sub List

Create

Client

ValueListHandler

DataAccessObject

ValueList

ValueListiterator

Return Sub List

Execute Search (index+count, count) Execute Search (index+count, count)

Return sub List

Create

Return Sub List

Stateless Session

Select * FROM item WHERE id=? LIMIT [count]OFFSET [startIndex]


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WEB Tier





COMMANDobject

Request Response

MODEL

DATATRANSFER

OBJECT



ACCESSOBJECT

DATATRANSFER

OBJECT

SessionEJB

Servlet

JSP

Java™ Objects

Session EJB


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Session Facade pattern Entity Bean 1

Entity Bean 2

Java™ Object

Data Access Object 2

Data Access Object 1

1. doThis(...)

2. getData()

3. process

2. getData()

Session BeanEntity BeanPlain Java™ Object

Use the Session Facade: provide a simple interface to a complex subsystem of

enterprise beans Enforce a clear and strict separation of business logic from

presentation and data logic

Session Facade

Client

Session Bean


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Direct Entity Bean access results in excessive network overheadand multiple transactions

Don’t: EJB

Network

Client

Direct Bean Access

Do:EJBNetwork

ClientFacade

Use the Session Facade pattern

Direct Entity Bean access results in excessive network overhead

To Execute complex use cases in a single network call to reduce network overhead


46

EJBclient

EJBObject

Network

Local vs. Remote Interfaces

Pass by Value:Serialize/deserialize method parameters

Pass by Reference:Better performance

Remote Interfaces Local Interfaces

EJBclient

EJBObject

Use the Session Facade To group finer grained calls to local entity beans


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Design your local & remote EJBs

AdminRemoteFacade

LineItem

Purchase Order

Address

CreditCard

RelationshipReference

JavaClient

RemoteFacade

WebComponent

WebComponent

WebComponent

BusinessDelegate

Determine which EJBswill be collocated within sameVM

Use Session Facade to group finer grained calls to local EJBs in a Coarse Grained Interface


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Use the Session Facade

Check contextx to see if updates will work

Application Server

Transaction Manager Transaction

context

DataBase Serveror JMS Provider

ResourceClient FacadeInventory

Order

Check OutTX_REQUIRED TX_REQUIRED

Create context x

Update Inventory

Add to context x

createOrder

Add to context x

Commitor rollbackStart Prepare

To group related updates into container managed transactions


49

eBay.com: Business Tier

DataSource

Dispatch

ApplicationController

BusinessLogic/Data

TransferObject

DAO

ApplicationServiceFacade

Persistence

ContextObject

TransferObject

Assembler

BusinessObject

ValueList

Handler

Domain Store

Core J2EE

Pattern

Strategy

Command

ebay Case Study


50

Session EJB tips

Remove stateful session beans when finished (user logs out) Bean.remove()

Limit size of objects stored in session beans due to memory cost and I/O for passivation


51

Stateless or Stateful Session EJB?

Stateless session beans are pooled and can service multiple clients give best performance Stateful store conversational state=1 per

client (are activated and passivated) For Performance Strive for Statelessness

when application has a high number of users convert Stateful to stateless by adding parameters

to the bean methods that hold the extra state


52

PersistenceBest

Practices


53

Data Access Options in J2EE:

Object-oriented (transactional) data model EJB Container Managed Persistence

Great choice for ease and performance JDO

Tabular access EJBs should not be simple wrappers on

database data rows; they should have business logic. To simply access data, use Plain JDBC encapsulated in a DAO

Non-relational, non-object data access, Legacy systems, CRM, SAP... Use J2EE Connectors


54

BMP vs. CMP

CMP Bean

EJB Container

BMPBean

EJB Container

JDBCDriver

JDBCSQLJ

SQL

JDBCDriver

SQL

PersistenceManager

BeanState

Database

BeanState

Database

JDBCSQLJ

1) Bean provider manages State and Data consistency2) Bean provider handles relationships and OR Mapping

1) Container manages State and Data consistency2) Container/PM provides concurrency, relationships and OR Mapping


55

CMP 2.0 Entity Beans

<<interface>>java.io.Serializable

CMP Entity Bean subclass(Contains persistence logic)

CMP Entity Bean abstract class(Contains data handling logic)

<<interface>>javax.ejb.EntityBean

<<interface>>javax.ejb.EnterpriseBean

You (bean provider) write this code.

Container provides this class.

Entity Bean is now an abstract class, container extends it


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Container Managed Relationships

1

1

1

M M

1

Local Entity

Local Entity

OrderBean Product

Address

Shipping Address

LineItems ProductOrdered

Client

Order

OrderHome LineItem

EJB TierLocal Entity


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Accessors for CMP and CMR

public abstract class OrderBean implements EntityBean {

private EntityContext context;

//access methods for cmp fields

public abstract String getOrderID(); //primary key public abstract void setOrderID(String id); . . . //access methods for cmr fields

public abstract Collection getLineItems(); public abstract void setLineItems(Collection lineItems);


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CMP 2.0 Relationship Handling

In CMP 2.0, you declare fields and relationships in deployment descriptor Container generates all the necessary code

<ejb-jar><enterprise-beans> ... define your enterprise beans ... <cmp-field> elements represent container-managed persistent fields

</enterprise-beans><relationships> ... define EJB relationships ...</relationships>


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Example CMP Wizard


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container manages the persistence and the relationships, not you! No SQL or persistence logic in source code

Freedom from maintaining interactions with the data store

EJB™ Query Language (EJB QL) Portable code

Advantages of CMP 2.0 for developer


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Optimization is possible because persistent fields are only accessible via get and set methods Containers knows

Which field is being accessed Whether or not field is in a relation Whether of not there is a transaction What's in cache The current clustering environment

Can optimize based on above

Advantages of CMP 2.0 for Container


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Some CMP Optimizations

Aggressive Loading Loading data for Entities in a relationship in the

same query Lazy Loading Deferring loading of any data until it is accessed

Dirty Writes Only update data which has been changed

in the database


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Standard features Declarative specification of:

Persistent attributes, abstract schema, relationships, queries for finder/select methods(via EJBQL), transactional attributes

Vendor specific Tools, concurrency and consistency

semantics, caching semantics, performance and usability

CMP: Standard Vs. Vendor Specific Features


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Pessimistic Locking

Time State inDatabase

Begin TxnBegin TxnBegin TxnBegin Txnread initialread initialread initialread initial balance w/Lock balance w/Lock balance w/Lock balance w/Lock........balance += 1000balance += 1000balance += 1000balance += 1000 ........CommitCommitCommitCommit

1000

20002000

Begin TxnBegin TxnBegin TxnBegin Txnread initial read initial read initial read initial balance w/lockbalance w/lockbalance w/lockbalance w/lock

(blocks ..)(blocks ..)(blocks ..)(blocks ..)

unblocksunblocksunblocksunblocks

balance += balance += balance += balance += 1000100010001000

CommitCommitCommitCommit

2000

3000 3000

C2C1

The entity blocks until previous transaction commits

1000

Serialized Access to same Bean


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Retry

3000

2000

Concurrent Access to same Bean (same Primary Key)Lock obtained at update time, conflict detection

Optimistic Locking With “ Update-conflict” Detection

Time State inDatabase

Begin TxBegin TxBegin TxBegin TxSelect initialSelect initialSelect initialSelect initial balance balance balance balance

........balance += 1000balance += 1000balance += 1000balance += 1000updateupdateupdateupdate........CommitCommitCommitCommit

1000

20002000

Begin TxBegin TxBegin TxBegin TxSelect initial Select initial Select initial Select initial balancebalancebalancebalance........

balance += 1000balance += 1000balance += 1000balance += 1000

updateupdateupdateupdate Exception Exception Exception Exception

........CommitCommitCommitCommit3000

C2C1

10001000

Concurrent Access to same Bean


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Usage Guidelines

Pessimistic Recommended for

consistency when concurrent updates would be frequent

Optimistic Use when

concurrent access is mostly reading

For scalability Requires

exception handlingSunOne deployment descriptor

<consistency><lock-when-loaded/>

</consistency>


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Chose optimistic concurrency forCMPs with “read-mostly” access

Tradeoff between performanceand consistency in transactions

Consistency Levels in CMP


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Sun Java System Application Server 7 supports these consistency levels(in sun-cmp-mappings.xml)– Check-modified-at-commit = most optimistic– Check-all-at-commit– Lock-when-modified– Lock-when-loaded = most pessimistic– None

Consistency Levels in CMP


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Database Isolation Modes

Choose the lowest cost database transaction isolation level that avoids corrupting the data.

Transaction levels in order of increasing consistency and cost are: Read Uncommitted Read Committed Repeatable Read Serializable consider READ COMMITTED with

optimistic locking


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Entity Bean Tips

Do not use EJB entity beans for batch loading or queries that return large result sets. Use Data Access Objets encapsulating JDBC

Use CMP rather than BMP entity bean when possible

Do not call EJB entity bean get & set methods from client Wrap with session beans to provide course

grain access and single transaction context


71

J2EE Performance Tips:

how to get the mostout of your Application

Server


72

Application Resources

Standard application resources: CPU Memory I/O Network Database


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Tune App Server

EJB Bean Cache and Pools JDBC connection pools Prepared statement cache size

JVM Heap size (go to garbage collection Performance session)

Correct settings depend on application, test to determine sizes


74

Tune Key Container Parameters

Stateful session bean and Entity bean cache Cache = EJB instances with state Minimizes activation and passivation

Stateless session and Entity bean pools Pool = EJB instances with no assigned state Minimizes creation and initialization


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The EJB Container

PoolingPoolingPoolingPooling CachingCachingCachingCaching

objective: minimize creation + activation /

initialization passivation

for message-driven yes no

for stateless session yes no

for stateful session no yes

for entity beans yes yes

Allow for reuse of bean instances

Pooling and Caching of EJB Instances


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Entity Bean

Does not exist

pooled

ready

NewInstance()setEntityContext() unsetEntityContext()

ejbCreate()ejbPostCreate()

ejbRemove()

business method

ejbStore()ejbLoad()

ejbFind()

ejbActivate() ejbPassivate()

EjbActivate()

EJBInstance

EJBObject

EJBInstance

Bean pool sizeminimizes creation and initialization

Bean cache sizeminimizes activation and passivation


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Entity Bean Caching

Commit Option A At the end of the transaction, the instance stays

ready (cached) and the instance state is valid Commit Option B At the end of the transaction, the instance stays

ready (cached) but the instance state is NOT valid ( ejbLoad will be called )

Commit Option C At the end of the transaction, neither the instance

nor its state is valid (passivated) Best Option: Usually B, if Entity will be

accessed again. do profiling with your application on your app server


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Stateful Session Bean

Method-ready

ejbRemove()

business method

does not exist

1) newInstance()

2) setSessioncontext()

3)ejbCreate() ejbPassivate()

EjbActivate()

passiveEJBInstance

EJBObject

removal time out

Bean cache sizeminimizes activation and passivation


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Stateless Session Bean and Message Driven Bean

EJBInstance

method-ready pool

EjbRemove()

Business method

does not exist

1) newInstance()

2) setSessioncontext()

3)ejbCreate()

Bean pool sizeminimizes creation and initialization


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The Sun's EJB Container

commit-option (B|C) (entity beans) Max-cache-size (0 = unbounded) cache-idle-timeout-in-seconds

(0 = indefinitely) removal-timeout-in-seconds

(stateful session) Adjust cache size: Increase until a good cache hit

rate is reached

– For fine tuning, understand a bean’s usagepattern (reads, updates, creates, removes ...)

Cache Tunables


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steady-pool-size (not for message-driven)

max-pool-size (0 = unbounded) pool-idle-timeout-in-seconds

(0 = indefinitely) Adjust a bean’s pool size:– Increase when observing excessive creation

and deletion of bean instances– Decrease when accumulating a large number

of instances in pool

Pool Tunables


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Per bean: in ejb module’s sun-ejb-jar.xml– <bean-pool> and <bean-cache> Global defaults: in server instance’s=

server.xml – <ejb-container> and <mdb-container>

Configuring Pool and Cache


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JDBC Tips

Select a good Thin JDBC driver Tune connection pool size Close resources as soon as you’re done

with them (in finally) E.g. Statements, Connections, ResultSets…

Use JDBC’s PreparedStatement when possible: stmt = connection.prepareStatement(..); Tune statement caching

Turn off Auto-Commit Group updates into a transaction


84

Database Statement Caching

Statement caching– 15–25% Performance improvement– Requires knowledge of database specific

properties, i.e. Oracle<jdbc-connection-pool datasource-classname= "oracle.jdbc.pool.OracleDataSource" ...>

<property name="ImplicitCachingEnabled" value="true"/>

<property name="MaxStatements" value="200"/></jdbc-connection-pool>


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Database Performance

Common performance bottleneck Typical problems: primary key to big (use integer) Inefficient queries - sending SQL data

that asks the database to do more work than necessary run the SQL through the EXPLAIN SELECT command index the columns in your WHERE clauses

Large Data Sets - processing large sets of data in ResultSets


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Performance Tips Summary

Tips for better performance Tune app server and infrastructure Container Caching and Pools

Database access Use JDBC for:

Batch loading: session bean or message bean Large result sets: value list handler

Use CMP rather than BMP Entity Beans Use right isolation level and database

transactional control (locking)


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EJB Tips Summary

EJB Container Services – use appropriately for: Distributed transaction management Robust security service Resource management (threads, sockets, database connections) Container persistence Remote accessibility Dispatch and life-cycle management.


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Manage Expensive Resources

Cache “EJB homes” Cache data sources Minimize use of HTTP sessions Release database connections Remove unused stateful session beans Use local Interfaces [Session Facade]


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Session Facade Service Locator Value List Handler Data Transfer Object

Design Patterns can Significantly Help Performance


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Some JMS Messaging, J2EE BestPractices


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JMS Communication

Consumer

JMS Provider

Loosely coupled: – Producer doesn't need to know consumers or consumer method

arguments Reliable: – Message is stored until it can be delivered Asynchronous – Producer is not blocked, consumer does not have to be available

Producer Destination


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Use JMS for

Asynchronous Interaction Concurrent processing Scalability Batch processing

Broadcasting messages to multiple recipients

Reliable messaging Messaging with Transaction Support Loose Coupling


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Message-Driven Bean

Container

Destin-

ation

Consumer

Msg-drivenBeanInstances

High Scalability, High Throughput MDB instances are pooled by the container Allow for asynchronous concurrent message consumption

from the same destination

JMS Provider

Container

QueueMDB

ConsumerMDB

Instances

Msg-DrivenBean Class

Concurrent Asynchronous Processing


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EJB Tier

Address Entity

OrderApproval

MDB

LineItem Entity

Mailer MDB

CardEntity

AsynchronousMessageDelivery

Purchase Order Entity

1:m

MDB Facade Pattern

Use the MDB Facade: provide a simple asynchronous interface to a complex

subsystem of enterprise beans


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JMS

Use JMS for loosely coupled applications that need reliable, scalable document oriented message exchange

Including Message-Driven Beans and JMS in your J2EE™ application can greatly increase performance, robustness, and efficiency


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XML Message Facade

EJB Architectural Pattern

ExternalApplication

JMSQueues

MessageDrivenBean

StatelessSession

EJB

EntityBean

XML Messaging Facade

Asynchronous Synchronous

Example implementation of XML interaction modelon top of Java™ interaction model

EntityBean

EntityBean

XMLmsg

Java™Value

Objects

Ref JavaOne


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Tips for XML messaging

Inside your Application don’t overuse XML Parsing and processing can cause a performance

hit Use XML for messages between

systems… Within a system just use java data objects

Convert the data from XML into a Java™ class as soon as possible Can use JAXB for this

Use XML mainly for transmission


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Asynchronous Web Services

RDBMSEAI ResourceAdapters

LegacySystems

Data Base

ERP

Business Services

Webcontainer

DomainObjects

EntityEJBMDB DAO

Connector

MDB

Soap

Message Services

EntityEJBMDB

SessionEJB

SessionEJB

BusinessDocument

Webcomponent


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FUTURE: JBI and J2EE

208 “Binding” SPI

208 “Machine” SPI

Binding Framework

WS-I EDI VAN

SOAP EIS resource AS1/AS2

EJB Module(EJB API)

JBI BP Module (WS-BPEL and WSDL APIs)

Normalized Message “Bus”

Web App. Module(JSP/ServletAPI)

JMS

MQ

JCA


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ToolsSummary

Resources


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Use Tools

Use IDE or Xdoclet to keep EJB class, home interfrace, remote interface consistent

Use Junit for Unit testing Use Ant to automate deployment and

testing All of these are provided with

Sun Java Studio


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Summary

J2EE Patterns and Best Practices are proven solutions Reuse design Robust and scalable architecture Improve quality, performance Flexibility and maintainability

JavaTM BluePrints Program http://java.sun.com/blueprints Designing Enterprise Applications

with the J2EE Platform, 2nd Edition


103

Resources:

http://java.sun.com/blueprints

J2EE Performance Testing

Java Performance Tuning


104

Carol McDonaldTechnology [email protected]

Sun™ Tech Days

J2EEBestPractices webinar

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