Java Tutorial - Java Scipt :
Enterprise applications often require an asynchronous method of communicating between components. This is addressed within J2EE by the notion of messaging. Messaging comprises two key pieces: JMS (Java Message Service) and message-driven beans. JMS is the standard Java API for messaging, while message-driven beans, which are built on JMS, are the standard J2EE component model for messaging. In this chapter, we will take a look at several open source JMS providers and show you how to use JMS within the J2EE architecture with message-driven beans.