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This book, now in its second edition, provides in-depth coverage of the Enterprise JavaBeans™ (EJB) 2.1 architecture. It describes how to develop and deploy enterprise applications using the latest EJB component architecture. This second edition covers the new features of the EJB architecture, including message-driven beans and asynchronous communication, enhanced container-managed persistence, support for Web services, and the EJB QL query language.
This book and the Java BluePrints program do not provide information on how to use individual Java technologies to write applications-that's the role of the companion Java Tutorial program. Instead, Java BluePrints focuses on guidelines for application architecture.
Readers of this book should be familiar with the Java™ programming language, have a basic knowledge of the J2EE platform, and should have had some exposure to enterprise beans and the EJB architecture. Although we briefly cover the basics of the EJB architecture, this book is not meant to be a tutorial for those just getting started with enterprise beans. Instead, the book provides in-depth coverage of the EJB 2.1 architecture for information technology (IT) personnel implementing applications in-house and for independent software vendors (ISVs) developing generic applications for sale to enterprises.
The EJB architecture defines these interactions as contracts, which enable applications to use components from different sources. Because EJB components must adhere to these contracts, an application can consist of software components from multiple vendors.
The EJB specification defines the architecture contracts mainly from the point of view of the container vendor. In contrast, this book presents the EJB architecture from the point of view of the application developer-that is, the person who develops EJB applications.
A detailed description of the development of two enterprise applications forms the backbone of the book. Although the example applications are relatively simple, they illustrate many of the typical problems encountered in enterprise application development. We use these examples to show how the EJB architecture helps developers solve these problems.
The first example is a benefits enrollment application developed in-house by an IT department. This application works well for explaining how a session bean works and for illustrating how developers use session beans.
The second example takes the benefits application from the first example, which was developed in-house, and turns it into an application developed by an ISV. An ISV has different design goals from that of an in-house IT department. The ISV must design the application so that it can be easily deployed in many different customers' operational environments. Because each customer has a unique operational environment, the ISV must address a number of challenges. In addition, an ISV typically needs to design the application so that it can be extended by a customer or integrator. We illustrate how the entity bean architecture helps ISVs to overcome these challenges.
The EJB 2.1 architecture makes it possible to implement applications as Web services. This updated edition of the book includes a chapter that describes how to incorporate and use enterprise beans in a Web service.
The EJB architecture defines a component model for enterprise applications. It describes:How to design an application as a set of components
How the components interact with each other
How the components interact with their EJB containerAbout the Authors
Vlada Matena is a Distinguished Engineer with the Java Software division of Sun Microsystems Inc., where he works on the J2EE architecture team. He is the Chief Architect of the Enterprise JavaBeans specification, and an architect of the JTS and JTA specifications.
Beth Stearns is the president of Computer Ease Publishing, a computer consulting firm she founded in 1982. Her client list includes Sun Microsystems Inc., Silicon Graphics Inc., Oracle Corporation, and Xerox Corporation, among others. Her Understanding EDT, a guide to Digital Equipment Corporation's text editor, has sold throughout the world. She received her B.S. degree from Cornell University and a master's degree from Adelphi University.