After completing this chapter, you will be able to:
Define a callback contract that enables a WCF service to call back in to a client application.
Create a client application that implements a callback contract.
Use a callback contract to build a simple mechanism for alerting client applications about significant events.
The examples and exercises that you have seen so far in this book have concentrated on the client/server model of processing. In this model, a server provides a service that waits passively for a request from a client application, handles that request, and then optionally sends a response back to the client application. The client application is the active participant, ...