What is an EPR? EPR stands for end-point reference, it is basically an address that the ESB uses to send messages to. The endpoint reference is linked to a service and is stored within the registry. In each message sent by JBoss ESB, multiple EPRs are sent in the headers—where the message came from, where it is going to, where it should default to, and reply to.

What we've just described is somewhat abstract, but it is important to understand because this is the meat of what JBoss ESB stores in its registry.