Pro WCF: Practical Microsoft SOA Implementation

Filtering

WCF has a concept of a filtering mechanism, which you can use to examine parts of messages and match them and then make some operational decision at runtime. This filtering mechanism is implemented as a set of classes and is designed to be fast with each filter implemented specifically for a certain kind of message matching. The filtering takes place after a message has been received and sits in the stack when the message is being dispatched to the relevant application. At this level, the filtering system can interact with all other WCF subsystems such as routing, security, event handling, and so on. An example is if there is a queue, then based on the priority of the message it can be moved to the front of the queue for processing. ...