Contents of the Book

The book begins by describing the advantages of the EJB architecture. Chapter 1, Advantages of the Enterprise JavaBeans™ Architecture, discusses the various enterprise application architectures and how they have evolved, especially with the growth of the Web. The chapter describes the current state-of-the-art EJB, J2EE, and Web services architectures and explains how they are well suited to meet today's enterprise computing needs.

Chapter 2, Enterprise JavaBeans Architecture Overview, provides a concise overview of the EJB architecture. For someone not so familiar with the EJB architecture, this chapter is a good starting point because it defines the EJB terminology and the structure of enterprise beans. The chapter defines and describes EJB applications and such basic concepts as business entities and business processes. It provides an overview of the various enterprise bean types, the parts that comprise an enterprise bean, and how to use enterprise beans to model business logic of enterprise applications.

The development of an EJB application can be thought of in terms of the tasks that need to be performed. To that end, Chapter 3, Enterprise JavaBeans Roles, delineates the roles and tasks involved during the application development process.

Once the stage has been set and the introductory material explained, the book focuses on session beans, entity beans, and message-driven beans. Two chapters focus on session beans and two chapters focus on entity beans. Chapter 4, Working with Session Beans, discusses typical programming styles for applications using session beans. This chapter is of interest to bean developers implementing session beans and to application programmers developing session bean clients. For bean developers, the chapter describes how best to implement the methods of a session bean. For application programmers developing session bean clients, the chapter shows how to use the session bean home, remote, and local interfaces properly. An extensive benefits enrollment application example illustrates the key points about session beans.

Chapter 5, Session Bean in Its Container, describes the support and services that an EJB container provides for a session bean. Containers typically provide services to session beans when they are deployed and customized for a particular operational environment and at runtime, when a client application invokes the session bean. Although the container services are hidden from the bean developer and the client programmer, these services go a long way in simplifying bean and application development. This chapter describes much of what goes on behind the scenes.

After completing the discussion of session beans, Chapter 6, Using Message-Driven Beans and Connectors, presents message-driven beans and their use in enterprise application integration (EAI). A message-driven bean, a new type of enterprise bean introduced in the EJB 2.0 architecture, enables asynchronous message-oriented communication with enterprise beans. This chapter presents the basic concepts of the Java™ Message Service (JMS) and then explains how to develop message-driven beans. The benefits enrollment application from Chapter 4 is extended to show how to integrate it with a payroll application in a loosely coupled manner using message-driven beans.

The book then shifts its focus to entity beans. Entity beans differ significantly from session beans. Chapter 7, Understanding Entity Beans, combines a presentation of the basic concepts regarding programming with entity beans, from both the client and bean developer points of view, with a discussion of the services that the container provides to entity beans. This chapter is analogous to Chapter 5 for session beans. The chapter also provides a detailed description of strategies for managing entity object state: bean-managed and container-managed persistence, including the EJB QL query language. Chapter 8, Entity Bean Application Example, takes the benefits enrollment application example used for session beans and shows how to write the same application using entity beans. The example illustrates many of the techniques for working with entity beans and using container-managed persistence, as well as how entity beans can be used by ISVs to make their applications reusable across many customers' operational environments.

Web services technologies have become prominent in the last few years as a means to integrate applications across enterprises using interoperable, standards-based protocols and service description formats. Chapter 9, Using Enterprise JavaBeans in Web Services, introduces Web services technologies. It discusses how to use the EJB architecture to build and access Web services using new Java standard APIs that are being developed.

Virtually all applications using enterprise beans rely on transactions. Chapter 10, Understanding Transactions, describes the EJB architecture approach to transaction demarcation. The chapter covers the essential aspects of transactions necessary for application developers.

Security is another area of critical importance to enterprise applications. The EJB architecture provides declarative support for security management. Chapter 11, Managing Security, describes the EJB security environment, particularly from the point of view of the application developer.

The book also includes an appendix and a glossary. Appendix A contains code samples of supporting classes. The complete, up-to-date EJB API reference can be found at http://java.sun.com/apis.html.