Jaron CollisCore ConceptA loosely coupled means of peer-to-peer communication. Asynchronous - messages can be processed in any order. Reliable - delivery can be guaranteed. JMS messagesJMS producersJMS consumersJMS providerJMS messagesMessage header - used for identification. Properties - application or provider-specific header fields. Body - content of the message, e.g. TextMessage or ObjectMessage.Point-To-PointPublish/SubscribeJMS producersImplements QueueSender (PtP) or TopicPublisher (P/S)JMS consumersImplements QueueReceiver (PtP) or TopicSubscriber (P/S) interface. Two ways of consuming messages: synchronously - an explicit message fetch using receive() or, asynchronously - message delivered by JMS provider using listener's onMessage()JMS providerJMS API defines common set of interfaces and associated semantics: the actual implementation is vendor specific. All adhere to JMS ensuring compatibility.Point-To-PointSenders address messages to a specific queue, from where receiving clients extract their messages (1 message = 1 consumer). The receiver acknowledges the successful processing of a message.Publish/SubscribeSenders address messages to a topic in a content hierarchy. Infrastructure distributes messages to current subscribers, message expires when all have been notified (1 message = many consumers). Has a timing dependency: you must subscribe before consuming. falsesoftware12002-11-27T15:10:32.711Z2003-01-04T22:19:34.103ZSun JMS Tutorialhttp://java.sun.com/products/jms/tutorial/Sun articles on messaginghttp://developer.java.sun.com/developer/technicalArticles/Networking/Articles on JMShttp://www.javaworld.com/channel_content/jw-message-index.shtml