This document discusses WCF routing and protocol bridging in Windows Communication Foundation (WCF). It describes how the routing service acts as a message router and client to route messages between endpoints that may have different transport or SOAP version requirements. It covers how filters can be used to examine messages and make routing decisions, and various types of filters like action and XPath filters. Finally, it shows an example of using a routing service to bridge between mismatched endpoints, enabling a client using one protocol to communicate with a server using a different protocol.