#Reactive WCF Duplex demo

This test app demonstrates the use of a WCF duplex service where the callback endpoint is wrapped in an IObservable. Normally wrapping the callback event in an IObservable.Replay() (as done in Client.PingPong.Do()) would cause a deadlock when waiting for the First() element to arrive from WCF. The reason for this behavior is that waiting for this First() element halts the executing thread, but the callback service (Pong) is also hosted on that thread. This would not only block the Client, but also the Host, since its message cannot be delivered.

Solution: Replacnig the IObservable.Replay() with IObservable.Replay(Scheduler.Default) (in Client.PingPong.Do()), which causes any waiting for Rx elements to happen on a different thread in the thread pool. That way the Pong ServiceHost is not blocked any more, and the entire method can complete.

How to run

• Open the solution (in VS2010 SP1) and build all projects.
• Either run an instance of the Host project, followed by running an instance of the Client project,...
• ...or run all NUnit tests in Client.Test.