Invoking Enterprise JavaBeans

An Enterprise JavaBean has two client interfaces: a remote interface and a home interface. The remote interface specifies the methods that the object's clients can invoke; the home interface defines how clients can create the object, which returns a reference to the object. The client uses both of these interfaces when invoking a method on a bean.

The events that occur when a client invokes a method within a bean are explained in the following diagram and steps:

Figure 2-1 Sequence of events in a session bean lifecycle

The numbers in the figure correspond to the following numbered steps:

1. Client 1 looks up home interface of bean X.

   During the JNDI lookup, the database creates a session for the server-side of the request.

2. Reference to home interface X is returned to client 1.

3. Client 1 invokes create on home interface X.

   The bean instance is created within the session that was established on the JNDI lookup.

4. Home interface X instantiates remote interface X. The container instantiates the bean for this client and is destroyed only when the client invokes the remove.

   The object reference of remote interface X is returned to client 1.

5. Client 1 uses remote interface X to invoke methods on bean instance X.

6. Remote interface X delegates call to a bean.

7. Client 1 invokes remove on remote interface X when it is done with the bean instance. This destroys the remote interface and the bean instance.

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