JBoss Messaging is a high performance JMS provider in the JBoss Enterprise Middleware Stack (JEMS). It is a complete rewrite of JBossMQ, which is the current default JMS provider in JBoss AS 4.x. JBoss Messaging will be the default JMS provider in JBoss AS 5.x and later, and it is the backbone of the JBoss ESB infrastructure. Compared with JBossMQ, JBoss Messaging offers vastly improved performance in both single node and clustered environments. Please see this wiki page [http://wiki.jboss.org/wiki/Wiki.jsp?page=JBossMessagingPerformanceResultsPre1_0] for performance benchamrks and Chapter 7 on how to generate your own performance benchmarks. It also features a much better internal architecture that would allow us to add more features in the future.