I have a WCF application that is using sessions.

Is there any central event to get thrown when a session ends? How can I find out when a session is ending WITHOUT (!) calling a method (network disconnect, client crashing - so no "logout" method call)?

The server is hosted as:

[ServiceBehavior(
    InstanceContextMode = InstanceContextMode.PerSession,
    ConcurrencyMode = ConcurrencyMode.Reentrant,
    UseSynchronizationContext = false,
    IncludeExceptionDetailInFaults = true
)]

Basically because it is using a callback interface.

Now, I basically need to decoubple the instance created from the backend store when the session terminates ;)

Any ideas?