input: [Category] Concurrency Management [Description] By default callbacks enter the client on worker threads. If the client is a Windows Forms object, you must marshal the calls to the UI thread. By default this is exactly what WCF will do if the client is a Windows Forms form. But if the client uses a worker thread to dispatch the calls, there will be no marshaling. The client may do so to avoid a deadlock if the service tries to call back during a service call. The download shows such a client that uses its own synchronization context to post messages back to its own UI thread to process the callbacks and avoid a deadlock. [Last Updated] 9/7/2006 [Title] 
output: UI Client and Worker Thread Callbacks