I got to use WCF callbacks recently and realized some of it's gotchas, which are listed here:
- Callbacks requires communication over duplex channel
- Requires all clients to implement the callback interface, exposed by the service
- BasicHttpBinding & WSHttpBinding don't support callbacks -- use their Dual versions instead
- Streaming data not supported by callbacks -- streaming is not reliable and Callbacks require reliable messaging
- Requires reliable messaging
- If the service restarts, callbacks are not possible until the client makes a service connection again & subscribes itself for callbacks.
If you'd like to know more about how to setup WCF callbacks etc use this link: http://msdn2.microsoft.com/en-us/magazine/cc163537.aspx