Grasping the Concepts Early

There is quite a bit of work ahead for you to learn and understand Enterprise JavaBeans. It will make the task much easier if you come to understand the concepts of the EJB architecture before you attempt to dive into the nuts and bolts of building enterprise applications using it.

You must solidify these ideas and concepts in your mind before you start soaking up the rest of the topics in this book. Everything else after this chapter is predicated on your understanding the concepts and ideas presented in this chapter. In reality, this might be a better approach anyway. Other EJB books attempt to introduce these ideas either immediately before or during the process of building your first enterprise beans. This doesn't give you a great deal of time to understand what's going on behind the scenes before you are exposed to what you need to do to build an EJB application. Take enough time to read this chapter thoroughly.

If you spend any time on the EJB-related newsgroups and discussion lists, you probably know that many of the questions that are being asked are related to the conceptual ideas about the EJB architecture, what the roles and responsibilities are for the many parties involved, and why things are done in a particular way. To ensure a consistent understanding for the rest of the book and to hopefully clear up some of these questions, we present the concepts of the EJB architecture here in this chapter, well ahead of the time that you will need to apply them.

If you feel that you already have a solid understanding of the basic concepts, feel free to jump ahead to Chapter 4, "Java Naming and Directory Interface," but do so at your own peril.