Head First EJB

Architectural overview: Message-driven beans

Message-driven beans don’t have a client view. That means they don’t have interfaces (Remote or local) that expose methods to the client. In other words, message-driven beans don’t have a Home or EJBObject. They don’t have a Home interface or a Component interface.

1. The client sends a message to a JMS messaging service.

2. The messaging service delivers the message to the container.

3. The container gets a message-driven bean out of the pool.

4. The container delivers the message to the bean (by calling the bean’s onMessage() MessageListener interface method).

Exercise

What goes where?

Place the objects and classes in the appropriate spot on either the client, the server, or in both places (yes, you can reuse an object). Note: not all the pieces are here, so when you’re done, if you can think of other things that should go into the picture (classes or objects) draw them in!

Exercise

Organize your beans

Finish the table by putting in a checkmark (even better if you add notes) in the boxes corresponding to the labels that apply to that bean type. We’ve done one of the boxes for you. If you get stuck, go back through the previous two chapters. You might have to make your best guess on a few things. That’s OK—you’ll have it all worked out way before the end of the ...