BEHAVIORS ARE WCF CLASSES that affect runtime operation. Behaviors are invoked as the WCF runtime starts on the client and server and as messages flow between the two. Because behaviors run at these critical times, they are used to implement many built-in features in the WCF. They are also an important extensibility point for customizations.
ServiceHost is responsible for defining the instancing and concurrency aspects of a server, in addition to dispatching messages to the proper operation. When a message is received by a service and dispatched to a certain method of a class, should
ServiceHost create a new instance of that class for each request or should it reuse instances? And when
ServiceHost calls the method on ...