Endpoint addresses are pretty volatile pieces of data. Services move around, and web administrators do not always exercise the best practices to prevent a physical relocation from becoming a logical one.
jBPM BPEL tries to rely on the address as little as possible. It resolves references to actual ports in the service catalog in the following manner:
if there is a service name look for that service if there is a port name get that port from the service, ignoring the given address otherwise look for a port that implements the partner port type, preferring one that matches the given address otherwise look for a service with a port that implements the partner port type, preferring one that matches the given address
Given the previous arguments, you might wonder why I write the <wsa:Address> at all. It's just that the schema document states it is required.
OK , thanks Alex