How to be notified if WCF Duplex session is prematurely closed

Question

I have a publish/subscribe scenario in WCF using net.tcp and Duplex callbacks. I have a number of clients that subscribe to the service, and this works fine. However, sometimes a client will close without unsubsribing (Client computer goes to sleep, computer crashes, network connection is aborted, etc..), this causes an exception to be thrown when I callback via my callback list.

Now, I can certainly catch the exception and remove the offending callback, but this seems less like an exception scenario to me and further along the lines of "expected behavior".

Is there an event that gets fired on connection close that will notify me so that I can remove the callback from my list? Consider that this is net.tcp and not HTTP, so connection state should be known.

Clearly the framework knows the connection has been closed and disposed because the exception is something along the lines of "attempt to call a disposed object".

EDIT:

I should point out, that this is not a long running transaction. It's a long running connection in a publish/subscribe scenario. Basically, the callback is used to notify transient subscribers of various events as they happen. Each event is isolated and not long running.

Answer 1

It has been a while, this is from memory so I could be wrong, but I think perhaps if you make an IEndpointBehavior that goes an pokes at the DispatchRuntime to add an IInputSessionShutdown, then you can get notified when the session channel ends.

http://msdn.microsoft.com/en-us/library/system.servicemodel.dispatcher.dispatchruntime.inputsessionshutdownhandlers.aspx