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Part V


Developing

Enterprise Scale Software


Chapter 21


Introduction to Enterprise JavaBeans


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This chapter will serve as an almost criminally brief introduction to Enterprise JavaBeans, their varieties, and their uses.

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21.1 WHAT YOU WILL LEARN


You will learn the basics of Enterprise JavaBeans and the Java Naming and Directory Interface, which is how applications and EJB’s meet up with one another.


21.2 EXPANDING TO EJBS


All right, we’ll admit it. It is a bit of a stretch to expand our sample application to the J2EE Enterprise JavaBean component model. The truth is, given the small data requirements and simplicity of our application, the Web front end that we put on our application in the previous chapters is probably sufficient to scale our application to even very large organizations.


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That confessed, we still think our example is the best way to address our topic. Why? Because EJBs are a large topic, worthy of several books (and we encourage you to read some of them, such as Enterprise JavaBeans Component Architecture by Gail Anderson and Paul Anderson (ISBN 0-13-035571-2). We simply cannot teach you all about EJBs in our book. Our goal here is to intro- duce the concepts, provide a working example, and explain how to deploy and maintain an EJB system on Linux using JBoss. Believe us, we’ll have enough to cover to achieve that modest goal.


 


21.2.1 EJB Concepts

21.2.2 Bean Types

Stateless Session Beans

Stateful Session Beans

21.2.3 Under the Hood

21.3.1 Naming and Directory System Concepts

21.3.2 Common Directory Services

21.3.3 Putting a Face to a Name: JNDI

21.3.4 Using JNDI with JBoss