As the original architecture document describes, routing of messages based on content is something that we will support, but it will be a natural part of the SOA platform. For example, WS-A provides support for routing (in fact, there was a WS-Routing specification that companies now agree is deprecated in favour). However, not all routing requirements cna be handled purely based on WS-A and some means of defining rules (specifically for content-based routing) is required. Since our messages will be in the form of XML, using XPath makes a lot of sense.