Paolo RamassoPrincipal Sales ConsultantOracle Fusion Middleware

Enterprise Java Beans Oracle Container 4 Java 10.1.3.1

(OC4J)

Oracle Fusion Middleware

Quick Intro...EJBs ???!!

• A Programming Model for Server Side Reusable Components

• Encapsulation of Business Logic• Allows Components to be Distributable Objects• Typical usage...Model in MVC

Why EJBs ???!!

• EJBs enable faster application development.• EJBs encapsulate business logic that can be

invoked by remote clients.• EJBs exist in the middle tier that provides

standard and robust architecture.• EJBs allow reuse of business components.• EJBs live in containers providing services such as

support for transactions, persistence, and access control for the beans.

EJB Architecture

EJB client

EJB server

Enterprise ServicesNaming Service, Transaction

Service, SecurityDeployment descriptor

Database

EJB container

EJB bean

EJB remote object

EJB home object

EJB remote

interface

EJB home

interface

“legacy EJB” EJB 2.x• 4 to 6 parts• Home/LocalHome Interface• the ‘lifecycle’ interface of the EJB• Defines the methods with which you create, retrieve

and destroy EJBs• consists of create method, finder methods (Entity

beans) and destroy methods• Remote/Local Interface• the ‘business’ Interface of the EJB• Defines which methods are exposed to a client

• Bean Class• the implementation of the EJB business methods

Types of EJBs

• Session Beans - Stateful- Stateless

• Entity Beans - Container Managed Persistence- Bean Managed Persistence (forget them!!!)

• MessageDriven Beans - Listen to JMS endpoints (queues/topics)

Types of EJBsSession Beans

• Stateless beans:Hold conversations that span a single method call (implement your business meths here)• Stateful beans:

Hold conversations with clients that may span many method calls(implement your business meths here)

Types of EJBsEntity Beans

• Business entities that are used to represent data in the database• Sharable across multiple clients• Are persistent: • Container managed persistent (CMP) beans - data

is persisted by the container so no SQL in the bean• Bean managed persistent (BMP) beans - data

maintained by the bean itself, so SQL in the bean

Container Managed Transactions

• Declarative Transaction Management• Specify Transaction Attributes in EJB Deployment

Descriptor• No Transactional logic in Business Logic

• Set Transaction Attributes for all methodsor individual methods in an EJB

• Mandatory • Required• RequiresNew• Supports• ...

Deployment Descriptor

• Deployment descriptor:• Specified in J2EE• Specifies run-time attributes of the bean for

deployment• Allows customization of the run-time behavior of

enterprise beans• EJB-jar files:

A standard format used by EJB deployment tools for packaging enterprise beans with their declarative information

Let’s move to EJB 3.0…

• Simplify Development• EJB = Plain Java Object (POJO)• Use metadata annotations• Reduce number of artifacts• Attract broad range of developers

• Standardize persistence API• O-R Mapping similar to Oracle TopLink,

Hibernate• EntityManager API for CRUD Operations

EJB 3.0 Simplification

• POJO and POJI• Removes complexity of earlier versions using

simple and familiar Java artifacts• EJB Class will be a POJO• EJB Interface will be a POJI (no EJB extensions)• No need for home interface• Annotations for type of EJB and interface

Oracle & EJB 3.0 Support

• OracleAS 10.1.3.0• Container was close to final draft

• OracleAS 10.1.3.1• Complete EJB 3.0 Support in the Container

• Aligns with Final Spec• Oracle extensions

• JPA Based on TopLink Essentials• Annotations support in Web and Application client

Container

Oracle & JPA 1.0

• EJB 3.0 and JPA 1.0 finalized at JavaOne 2006• Oracle keynote and demonstration grounds

• Project Glassfish reference implementation of JPA • Provided by TopLink Essentials

• OracleAS 10.1.3.1 EJB 3.0/JPA 1.0 updates• EJB 3.0 final version• JPA 1.0 – default to TopLink Essentials• Oracle JDeveloper – updates to match runtime• Eclipse Dali – M3 release at JavaOne

Configuration by Exception

• Minimize configuration• Use generally accepted defaults• Only configure that what is different from the

defaults

Working with Dependency Injection

Dependency injection:• Eliminates use of JNDI complexities• Results in less lines of code• Yields more concise code• Can be overridden with XML elements in deployment

descriptors• Can't be used with helper classes, which must use

JNDI services

EJB 3.0 Annotations

Metadata annotations & deployment descriptor:• Deployment properties • Persistence

Annotations are optional (J2SE 1.5 is required) deployment descriptors can also be used, ala EJB 2.1

Examples:@Resource, @EJB etc…

The @EJB The @Resource

Session Beans and Interfaces package ejb30test;import javax.ejb.Remote;@Remotepublic interface EJBInjecter {

public String facadeMeth(String s);}

package ejb30test;

import javax.ejb.Local;@Localpublic interface EJBInjecterLocal {}

Session Beans and Injection

@Stateless(name="EJBInjecter")public class EJBInjecterBean implements EJBInjecter,

EJBInjecterLocal {

@EJB(beanName="EJBToBeInjected", beanInterface=EJBToBeInjected.class)EJBToBeInjected ejbinjected;

@EJB(beanName="EJBToBeInjected", beanInterface=EJBToBeInjectedLocal.class)EJBToBeInjectedLocal ejbinjectedlocal;

Session Beans and Injection@Stateful(name="WhatDriverEJB")public class WhatDriverEJBBean implements

WhatDriverEJB, WhatDriverEJBLocal {@Resource(name="jdbc/OracleDS") public DataSource mylocalscott;

…try

{System.out.println("getting a new

connection from the pool");conn= mylocalscott.getConnection();

}

Stateful Session Beans and Callback Interceptor Methods

@StatefulDeployment(idletime=10,timeout=15)@Stateful(name="WhatDriverEJB")public class WhatDriverEJBBean implements WhatDriverEJB,

WhatDriverEJBLocal {…@PostConstruct

public void itIsAnInit() {System.out.println("PostConstruct

WhatDriverEJBBean.itIsAnInit");try{System.out.println("getting a new connection from

the pool");conn= mylocalscott.getConnection();}

…

Stateful Session Bean and Callback Interceptor Methods

@PrePassivatepublic void goPassivate() {

…@PostActivate

public void goActivate() {…@Remove

public void iMDone() {System.out.println("WhatDriverEJBBean.iMDone");}

EJB Client Samplepublic class WhatDriverEJBClient2 {

public static void main(String [] args) {try {

final Context context = getInitialContext();WhatDriverEJB whatDriverEJB =

(WhatDriverEJB)context.lookup("WhatDriverEJB");// Call any of the Remote methods below to access the EJB

whatDriverEJB.justKick( );// whatDriverEJB.iMDone( ); to force remove

} catch (Exception ex) {ex.printStackTrace();

}}private static Context getInitialContext() throws

NamingException {…

Interceptors

EJB 3.0 introduces the ability to create custom interceptor methods and classes that are called before invoking the methods they intercept.

Interceptors are:• available for session beans (stateless and stateful) and

message-driven beans• Provide more granular control of a bean's method invocation

flow• Useful to implement custom transaction, security,

logging…AOP

Interceptors

@Stateless(name="BasicEJB")@Interceptors({LogMyTest.class, GenericInfo.class})public class BasicEJBBean implements BasicEJB, BasicEJBLocal

{public BasicEJBBean() {

System.out.println("BasicEJBBean.BasicEJBBean");}

…@AroundInvokepublic Object thatSIt(InvocationContext ctx) throws

Exception {System.out.println("BasicEJBBean.thatSIt I HOPE YOU

LIKE MY INTERCEPTOR DEMO");return ctx.proceed();

}

Interceptorspublic class LogMyTest {

@Resourceprotected SessionContext sessionCtx;

public LogMyTest() {System.out.println("LogMyTest.LogMyTest");

}@AroundInvokepublic Object iGotIt(InvocationContext ctx) throws

Exception {

System.out.println("iGotIt: I GOT YOUR CALL AND YOU ARE LOGGED AS "+sessionCtx.getCallerPrincipal());

return ctx.proceed();}

@WebService

package jmssenderws;import javax.ejb.Local;

import javax.jws.WebService;

@WebServicepublic interface SessionEJBJMSWSLocal {

public String pushIt(String s);}

EJB 3.0 WS: you may choose to annotate an interface or the bean class using @WebService annotation or use @WebMethod to annotate class methods to be exposed as WS operation.

@WebService

@Stateless(name="SessionEJBJMSWS")public class SessionEJBJMSWSBean implements

SessionEJBJMSWSLocal {…

public String pushIt(String s) {System.out.println("SessionEJBJMSSenderBean.pushIt");

MessageProducer producer = null;Connection connection = null;try {

Message Driven Beans 3.0…@MessageDriven(activationConfig =

{@ActivationConfigProperty(propertyName="connectionFactoryJndiName",propertyValue="jms/QueueConnectionFactory"), @ActivationConfigProperty(propertyName="destinationName", propertyValue="jms/demoQueue"), @ActivationConfigProperty(propertyName="destinationType", propertyValue="javax.jms.Queue")})

public class MessageDrivenEJB30Bean implements MessageListener {public void onMessage(Message message) {

…}

EJB 3.0 and JAASEJB security roles:• Provide role-based access control of EJBs and their

methods• Are implemented through security annotations• – @DeclareRoles• – @RolesAllowed• – @PermitAll• – @DenyAll• – @RunAs

EJB 3.0 and JAAS@Stateless(name="SecureEJB")public class SecureEJBBean implements SecureEJB,

SecureEJBLocal {@Resource SessionContext ctx;

…@RolesAllowed("admrole")public void adm() {

System.out.println("name"+ctx.getCallerPrincipal().getName());

System.out.println("adminrole"+ctx.isCallerInRole("admrole"));

System.out.println("userrole"+ctx.isCallerInRole("usrrole"));

…

“Mr. Persistence Manager”Toplink Essentials

• Move to lightweight POJO solutions• Has always been supported by TopLink• Used by majority of our customer base

• Standardization of ORM support in Java EE• EJB 3.0 (JSR 220)

• Need and benefits of ORM solutions are better recognized

EJB 3.0 Persistence• Lightweight POJO entity model

• Portable (Serialization – detachment), • Container transaction and security config

simplified• Modularized EntityManager API • Usable outside container (Java SE)

• Standardized O/R mappings • Specified using annotations and/or XML• Supporting multiple tables, etc.

• Dynamic queries, named queries and SQL queries

Application

RDBMS

EntityManager

MyEntity Application

Components

Persistence.xml

ORM XML

MyEntityMyEntityMyEntity

find(…)create*Query(…)persist(…)remove(…)merge(…)refresh(…)contains(…)flush()

EntityManagerFactory

EJB 3.0 Persistence EJB Development

• EJB 3.0 Development• Simplified EJB development

• JPA support• Including Testing outside the

container• Dialog based EJB creation• Reverse engineering DB into

Entity Beans• Session Façade Generation• One-click sample client creation

for testing

An Entity…import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.NamedQuery;import javax.persistence.Table;@Entity@NamedQuery(name="findAllDog", query="select

object(o) from Dog o")@Table(name="DOG")public class Dog implements Serializable {

private Long age;private Long dogid;private String name;

public Dog() {}

An Entity…public Long getAge() {

return age;}public void setAge(Long age) {

this.age = age;}@Id@Column(nullable=false)public Long getDogid() {

return dogid;}public void setDogid(Long dogid) {

this.dogid = dogid;}

…

Some Mapping Annotations• Direct

• @Basic• @Lob…

• Relationship• @OneToOne• @ManyToOne• @ManyToMany• …

• @Transient – attribute not persistent

Mappings Examples@Entity@NamedQuery(name="findAllDog", query="select

object(o) from Dog o")@Table(name="DOG")public class Dog implements Serializable {…private List<Rate> rateList;…@OneToMany(fetch =FetchType.Lazy, mappedBy="dog")

public List<Rate> getRateList() {return rateList;

}public void setRateList(List<Rate> rateList) {

this.rateList = rateList;}

More Mapping Examplespublic class Distintaanticipo implements Serializable {

@SequenceGenerator(name="D_SEQ", sequenceName="DISTINTAANTICIPO_SEQ")@Id @GeneratedValue(generator="D_SEQ")@Column(name="K_DISTINTA", nullable = false)private Long kDistinta;private String operator;private Timestamp submission;@OneToMany(mappedBy = "distintaanticipo"

,cascade=CascadeType.PERSIST)private List<Distintaappuntoant> distintaappuntoantList;@OneToOne(cascade=CascadeType.PERSIST)@JoinColumn(name="K_RIF_INTERNO_DOC",

referencedColumnName = "K_RIF_INTERNO_DOC")private Appuntodocumento appuntodocumento;

Other Annotations

• Optimistic Locking• @Version

• Inheritance• @Inheritance• Strategy = InheritanceType

• InheritanceType• SINGLE_TABLE• TABLE_PER_CLASS• JOINED

Inheritance Example• @Entity

@Table(name="EJB_PROJECT")@Inheritance(strategy=JOINED, discriminatorValue="P")@DiscriminatorColumn(name="PROJ_TYPE")public class Project implements Serializable{...}@Entity@Table(name="EJB_LPROJECT")@Inheritance(discriminatorValue="L")public class LargeProject extends Project {...}@Entity@Table(name="EJB_PROJECT")@Inheritance(discriminatorValue="S")public class SmallProject extends Project {...}

EntityManager API• Querying

• Retrieval of Entities from database• Transactions

• Applying Changes to Entities• General

• isOpen()• close()• contains(Object entity)

• Persistence API Usage• Container Managed• Application Managed

Entity Manager Injection@Stateless(name="FacadeEJB")public class FacadeEJBBean implements

FacadeEJB, FacadeEJBLocal {@PersistenceContext(unitName="ejb30persist")

private EntityManager em;

public FacadeEJBBean() {}

public Object mergeEntity(Object entity) {return em.merge(entity);

}…

Writing Basic JPQL StatementsSELECT object(o)FROM abstract-schema-name o[WHERE condition]

Examples:SELECT object(o) FROM Users o

SELECT object(o) FROM Users oWHERE o.email = 'steve.king@srdemo.org'

SELECT object(o) FROM Users oWHERE o.firstName = :givenName

Querying API

• find(Class/String entityType, Object primaryKey)• refresh()• createQuery(String ejbql)• createNamedQuery(String queryName)• createNativeQuery(String sql, Class/String

entityType)

EntityManager Find

• Employee employee = (Employee)em.find("Employee", id);

• Employee employee = em.find(Employee.class, id);

Named Query Example

@Entity@NamedQueries({@NamedQuery(name="findADogbyname",

query="select object(o) from Dog o where o.name=:am"),@NamedQuery(name="findAllDog", query="select object(o) from Dog o")})

@Table(name="DOG")public class Dog implements Serializable {…

Named Query Example…@Stateless(name="SessionEJB")public class SessionEJBBean implements SessionEJB,

SessionEJBLocal {

…/** <code>select object(o) from Dog o where o.name=:am</code> */public Dogs findADogbyname(Object am) {return

em.createNamedQuery("findADogbyname").setParameter("am", am).getResultList(); }

…

Transaction API

• merge(Object entity)• persist(Object entity)• remove(Object entity)• Etc…

Persisting New Entities

import javax.persistence.EntityManager;

@Stateless(name="SessionEJB")public class SessionEJBBean implements

SessionEJB, SessionEJBLocal {

@PersistenceContext(unitName="ejb30persist")private EntityManager em;

public Object persistEntity(Object entity) {em.persist(entity);return entity;

}

Merging Detached Entities

import javax.persistence.EntityManager;

@Stateless(name="SessionEJB")public class SessionEJBBean implements

SessionEJB, SessionEJBLocal {

@PersistenceContext(unitName="ejb30persist")private EntityManager em;

public Object mergeEntity(Object entity) {return em.merge(entity);

}

Removing Entities

import javax.persistence.EntityManager;

@Stateless(name="SessionEJB")public class SessionEJBBean implements

SessionEJB, SessionEJBLocal {

@PersistenceContext(unitName="ejb30persist")private EntityManager em;

public void removeEntity(Object entity) {em.remove(em.merge(entity));

}

Refreshing Entities

import javax.persistence.EntityManager;

@Stateless(name="SessionEJB")public class SessionEJBBean implements

SessionEJB, SessionEJBLocal {

@PersistenceContext(unitName="ejb30persist")private EntityManager em;

public Object refreshEntity(Object entity) {em.refresh(entity);return entity;

}

EJB Transaction ModelDemarcating a transaction determines:

• Who begins and ends a transaction• When each of these steps occur• A container-managed (declarative) transaction (CMT):– Is demarcated by the container– Is specified implicitly (by default) or declarativelythrough the use of annotations

• A bean-managed (explicit) transaction (BMT):– Is demarcated by the bean– Is specified programmatically in the bean through JTAinterface or Java Database Connectivity (JDBC) interface

Container-Managed Transactions

@TransactionManagement(CONTAINER)• Container-Managed Transactions can specify one ofthe following @TransactionAttribute annotations:– REQUIRED (default)– SUPPORTS– MANDATORY– NEVER– REQUIRES_NEW– NOT_SUPPORTED• The transaction attribute can be specified at:– Class Level: Applies to all Business Methods– Method Level: Applies to Method

Container-Managed Transactions

CMT - setRollbackOnly() – getRollbackOnly()

• The setRollbackOnly() method controlstransaction state in the bean for a CMT.

• The setRollbackOnly() method can mark currenttransaction for rollback.

• If a transaction is marked for rollback, then container rolls back the transaction before returning to the caller.

Bulk UPDATE and DELETE in EJB QL

Perform batch update operations by using the Query API executeUpdate() method:

• EJB QL UPDATE example: To modify the first name and email address of a specified user

Query query = em.createQuery( "UPDATE Users u " + " SET u.firstName = 'Stephen'," + " u.email = 'stephen.king@srdemo.org'" +

" WHERE u.userId > 10");

int rowCount = query.executeUpdate();

Bulk UPDATE and DELETE in EJB QL

Perform batch delete operations by using the Query API executeUpdate() method:

EJB QL DELETE example: to delete the notifications rows for a specific user

Query query = em.createQuery("DELETE FROM Notifications WHERE n.userId > '10'");int rowCount = query.executeUpdate();

Support for Existing Applications

• A client written to the EJB 3.0 API may be a client of a component written to the EJB 2.1 or earlier API. Such clients may access components written to the EJB 3.0 APIs and components written to the earlier EJB APIs within the same transaction.

• EJB clients may access EJB 3.0 entities and/or theEntityManager together with EJB 2.x entity beans within the same transaction as well as within separate transactions.

Support for Existing Applications

• Existing EJB 2.1 and earlier applications must be supported to run unchanged in EJB 3.0 containers.

• All EJB 3.0 implementations must support EJB 1.1, EJB 2.0, and EJB 2.1 deployment descriptors for applications written to earlier versions of the Enterprise JavaBeans specification.

• An enterprise bean that is written to the EJB 2.1 or earlier API release may be a client of components written to EJB 3.0 API using the earlier EJB APIs when deployed in an EJB 3.0 container.

Oracle EJB 3.0 Extensions… Oracle EJB 3.0 Extensions…

• Vendor specific deployment annotations• Match with commonly used attributes in

• Simplification of using JPA• Ability to inject EntityManager using @Resource• persistence.xml is option in ejb-jars• Package a persistence.xml in WEB-INF/ instead of

WEB-INF/classes/META-INF

@StatelessDeployment(minInstances = 100, maxInstances = 500, poolCacheTimeout = 120)@Statelesspublic class HelloWorldBean implements HelloWorld

Oracle EJB 3.0 Extensions… Some Help

Pro EJB 3Java Persistence API■ ■ ■

Mike KeithMerrick SchincariolPro EJB 3: Java Persistence APICopyright © 2006 by Mike Keith and Merrick Schincariol

Summary• EJB 3.0 containers provide new feats like injection etc…to boost

programming easiness• EJB 3.0 fully leverages annotations• EJB 3.0 and WS development simpler than before• EJB 3.0 provides a standardized API and metadata format for

accessing ORM functionality• TODAY OracleAS 10.1.3.1 provides an EJB 3.0 implementation

based on Toplink• TopLink Essentials (EJB 3.0 RI)• You can have different EJBs version working together

Thanks for Your time