Java Message Service (JMS)

The JMS specification provides developers with a standard Java API for enterprise messaging services such as reliable queuing, publish and subscribe communication, and various aspects of push/pull technologies. JMS is the enterprise Java standard for messaging. It enables applications and components in Java to send and receive messages. WebLogic Server provides a complete implementation of the JMS standard.

There are several paradigms for messaging in JMS, including:

• Queue model

• Topic-based, publish-subscribe system

The queue model enables JMS clients to push messages onto a JMS queue. Clients can then retrieve these messages. The topic-based model enables publishers to send messages to registered subscribers of the JMS topic.

WebLogic Server adds a number of features in its implementation of the JMS specification that are allowed by the specification but are not part of Sun's reference implementation:

• Implementation of a guaranteed messaging service. This messaging service uses the database or a file storage mechanism in order to make sure that messages are durable (able to persist when either the server or the client goes down).

• Message filtering. The WebLogic Server JMS implementation enables you to designate rules to filter the distribution of messages.

Chapter 7 discusses the technical details for using JMS.