WS-Addressing article
Nice article of Steve Vinovski about endpoint references.
Multitechnology services — those accessed via multiple protocols, transports, or middleware systems — avoid technology stovepipes. Thus, references for such services must convey all means of access that a service wishes to make known to its consumers. Let's consider typical Internet services. As Rich Salz of Datapower Technology (www.datapower.com/) points out, Internet servers are often implemented as multiport applications in which each port handles a different protocol.2 In general, a service might make itself available over multiple ports to offer different qualities of service (QoS) to different consumers. For example, it might accept compressed messages over one port, encrypted messages over another, and, perhaps, management messages over a third. Another service might accept Corba messages on one port and SOAP messages on another