Document Information

Preface

Part I Introduction

1.  Overview

2.  Using the Tutorial Examples

Part II The Web Tier

3.  Getting Started with Web Applications

4.  JavaServer Faces Technology

5.  Introduction to Facelets

6.  Expression Language

7.  Using JavaServer Faces Technology in Web Pages

8.  Using Converters, Listeners, and Validators

9.  Developing with JavaServer Faces Technology

10.  JavaServer Faces Technology: Advanced Concepts

11.  Using Ajax with JavaServer Faces Technology

12.  Composite Components: Advanced Topics and Example

13.  Creating Custom UI Components and Other Custom Objects

14.  Configuring JavaServer Faces Applications

15.  Java Servlet Technology

16.  Uploading Files with Java Servlet Technology

17.  Internationalizing and Localizing Web Applications

Part III Web Services

18.  Introduction to Web Services

19.  Building Web Services with JAX-WS

20.  Building RESTful Web Services with JAX-RS

21.  JAX-RS: Advanced Topics and Example

Part IV Enterprise Beans

22.  Enterprise Beans

What Is an Enterprise Bean?

Benefits of Enterprise Beans

When to Use Enterprise Beans

Types of Enterprise Beans

What Is a Session Bean?

Types of Session Beans

Stateful Session Beans

Stateless Session Beans

Singleton Session Beans

When to Use Session Beans

What Is a Message-Driven Bean?

What Makes Message-Driven Beans Different from Session Beans?

When to Use Message-Driven Beans

Accessing Enterprise Beans

Using Enterprise Beans in Clients

Portable JNDI Syntax

Deciding on Remote or Local Access

Local Clients

Accessing Local Enterprise Beans Using the No-Interface View

Accessing Local Enterprise Beans That Implement Business Interfaces

Remote Clients

Web Service Clients

Method Parameters and Access

Isolation

Granularity of Accessed Data

The Contents of an Enterprise Bean

Packaging Enterprise Beans in EJB JAR Modules

Packaging Enterprise Beans in WAR Modules

Naming Conventions for Enterprise Beans

Further Information about Enterprise Beans

23.  Getting Started with Enterprise Beans

24.  Running the Enterprise Bean Examples

25.  A Message-Driven Bean Example

26.  Using the Embedded Enterprise Bean Container

27.  Using Asynchronous Method Invocation in Session Beans

Part V Contexts and Dependency Injection for the Java EE Platform

28.  Introduction to Contexts and Dependency Injection for the Java EE Platform

29.  Running the Basic Contexts and Dependency Injection Examples

30.  Contexts and Dependency Injection for the Java EE Platform: Advanced Topics

31.  Running the Advanced Contexts and Dependency Injection Examples

Part VI Persistence

32.  Introduction to the Java Persistence API

33.  Running the Persistence Examples

34.  The Java Persistence Query Language

35.  Using the Criteria API to Create Queries

36.  Creating and Using String-Based Criteria Queries

37.  Controlling Concurrent Access to Entity Data with Locking

38.  Using a Second-Level Cache with Java Persistence API Applications

Part VII Security

39.  Introduction to Security in the Java EE Platform

40.  Getting Started Securing Web Applications

41.  Getting Started Securing Enterprise Applications

42.  Java EE Security: Advanced Topics

Part VIII Java EE Supporting Technologies

43.  Introduction to Java EE Supporting Technologies

44.  Transactions

45.  Resources and Resource Adapters

46.  The Resource Adapter Example

47.  Java Message Service Concepts

48.  Java Message Service Examples

49.  Bean Validation: Advanced Topics

50.  Using Java EE Interceptors

Part IX Case Studies

51.  Duke's Bookstore Case Study Example

52.  Duke's Tutoring Case Study Example

53.  Duke's Forest Case Study Example

Index

 

The Lifecycles of Enterprise Beans

An enterprise bean goes through various stages during its lifetime, or lifecycle. Each type of enterprise bean (stateful session, stateless session, singleton session, or message-driven) has a different lifecycle.

The descriptions that follow refer to methods that are explained along with the code examples in the next two chapters. If you are new to enterprise beans, you should skip this section and run the code examples first.

The Lifecycle of a Stateful Session Bean

Figure 22-3 illustrates the stages that a session bean passes through during its lifetime. The client initiates the lifecycle by obtaining a reference to a stateful session bean. The container performs any dependency injection and then invokes the method annotated with @PostConstruct, if any. The bean is now ready to have its business methods invoked by the client.

Figure 22-3 Lifecycle of a Stateful Session Bean

Diagram showing the lifecycle of a stateful session bean.

While in the ready stage, the EJB container may decide to deactivate, or passivate, the bean by moving it from memory to secondary storage. (Typically, the EJB container uses a least-recently-used algorithm to select a bean for passivation.) The EJB container invokes the method annotated @PrePassivate, if any, immediately before passivating it. If a client invokes a business method on the bean while it is in the passive stage, the EJB container activates the bean, calls the method annotated @PostActivate, if any, and then moves it to the ready stage.

At the end of the lifecycle, the client invokes a method annotated @Remove, and the EJB container calls the method annotated @PreDestroy, if any. The bean’s instance is then ready for garbage collection.

Your code controls the invocation of only one lifecycle method: the method annotated @Remove. All other methods in Figure 22-3 are invoked by the EJB container. See Chapter 45, Resources and Resource Adapters for more information.

The Lifecycle of a Stateless Session Bean

Because a stateless session bean is never passivated, its lifecycle has only two stages: nonexistent and ready for the invocation of business methods. Figure 22-4 illustrates the stages of a stateless session bean.

Figure 22-4 Lifecycle of a Stateless Session Bean

Diagram showing the lifecycle of a stateless session bean.

The EJB container typically creates and maintains a pool of stateless session beans, beginning the stateless session bean’s lifecycle. The container performs any dependency injection and then invokes the method annotated @PostConstruct, if it exists. The bean is now ready to have its business methods invoked by a client.

At the end of the lifecycle, the EJB container calls the method annotated @PreDestroy, if it exists. The bean’s instance is then ready for garbage collection.

The Lifecycle of a Singleton Session Bean

Like a stateless session bean, a singleton session bean is never passivated and has only two stages, nonexistent and ready for the invocation of business methods, as shown in Figure 22-5.

Figure 22-5 Lifecycle of a Singleton Session Bean

Diagram showing the lifecycle of a singleton session bean.

The EJB container initiates the singleton session bean lifecycle by creating the singleton instance. This occurs upon application deployment if the singleton is annotated with the @Startup annotation The container performs any dependency injection and then invokes the method annotated @PostConstruct, if it exists. The singleton session bean is now ready to have its business methods invoked by the client.

At the end of the lifecycle, the EJB container calls the method annotated @PreDestroy, if it exists. The singleton session bean is now ready for garbage collection.

The Lifecycle of a Message-Driven Bean

Figure 22-6 illustrates the stages in the lifecycle of a message-driven bean.

Figure 22-6 Lifecycle of a Message-Driven Bean

Diagram showing the lifecycle of a message-driven bean.

The EJB container usually creates a pool of message-driven bean instances. For each instance, the EJB container performs these tasks.

  1. If the message-driven bean uses dependency injection, the container injects these references before instantiating the instance.

  2. The container calls the method annotated @PostConstruct, if any.

Like a stateless session bean, a message-driven bean is never passivated and has only two states: nonexistent and ready to receive messages.

At the end of the lifecycle, the container calls the method annotated @PreDestroy, if any. The bean’s instance is then ready for garbage collection.