Enterprise JavaBeans 3.1, 6th Edition

Chapter 4. Developing Your First EJBs

Now that we’ve covered the concepts behind the various component models and container services provided by the specification, it’s time to start putting these lessons into practice. In this chapter we’ll introduce the terminology and syntax necessary to code, package, deploy, and test some functional EJBs.

Step 1: Preparation

Let’s briefly lay out some definitions and conventions, and then we’ll get to hacking away.

Definitions

EJBs are composed from the following.

Bean implementation class (session and message-driven beans)

This class, written by the bean provider, contains the business logic for a session or message-driven bean. It is annotated with the appropriate bean type: @javax.ejb.Stateless, @javax.ejb.Stateful, or @javax.ejb.MessageDriven. For instance:

@javax.ejb.Stateless
public class MyFirstBean{...}

is all that’s needed to declare an SLSB.

Bean instance (session and message-driven beans)

The EJB Container internally contains one or more instances of the bean implementation class to service session or message-driven invocations. These are not exposed to the client, but are instead abstracted out by way of the client view. Entity bean instances are POJOs that may be created directly by the client using the new operator.

Client view (session and message-driven beans)

Because clients do not invoke upon bean instances directly, this is the contract with which a client will interact with the EJB. In the case of a session bean, the client view will ...