Apache activemq is a message broker built around java message service (jms) api : allow sending messages between two or more clients in a loosely coupled, reliable, and asynchronous way.

this message broker supports :
* jms 1.1 and j2ee 1.4 with support for transient, persistent, transactional
and xa messaging
* spring framework, cxf and axis integration
* pluggable transport protocols such as in-vm, tcp, ssl, nio, udp, multicast,
jgroups and jxta
* persistence using jdbc along with journaling
* openwire (cross language wire protocol) and
stomp (streaming text orientated messaging protocol) protocols
this package contains a core java library for activemq.