Since message-driven beans are based on the Java Message Service (JMS) technology, in order to understand the example in this chapter you should already be familiar with basic JMS concepts such as queues and messages. The best place to learn about these concepts is the Java Message Service Tutorial: http://java.sun.com/products/jms/tutorial/index.html This chapter describes the source code of a simple message-driven bean example. Before proceeding, you should read the basic conceptual information in What is a Message-Driven Bean?.