I’ve been talking to customers for months about Mule, one of the first open source Enterprise Service Bus (ESB) implementations. I just ran across ServiceMix which is also an open source ESB built around JBI (JSR 208) principles, semantics and APIs. According to the ServiceMix website, “ServiceMix is lightweight and easily embeddable, has integrated Spring support and can be ran at the edge of the network (inside a client or server), as a standalone ESB provider or as a service within another ESB. You can use ServiceMix in Java SE or a Java EE application server.” Definitely worth checking out.