Whats the relation between JBoss Messaging and HornetQ?
During most of its development the HornetQ code-base was known as JBoss Messaging 2.0. We decided to rename it and spin it off as an independent project since it differs in a great many ways from JBoss Messaging 1.x and we did not want to confuse JBoss Messaging 1.x with JBoss Messaging 2.x. The vast majority of the code base of HornetQ is different to the code base of JBoss Messaging 1.x. JBoss Messaging 1.x continues to be known under the name of JBoss Messaging and the project is now in maintenance mode only, with all new messaging development happening on the HornetQ project.