Silverlight

Yesterday I posted a long blog post explaining how to do duplex communications in a Workflow service. Its a long story but the most important points where that workflow services don’t support the same style duplex communication as WCF with the callback channel defined in the ServiceContract but rather something that is called durable duplex where the callback contract is independent and the client has to create a ServiceHost and act as a full-blown WCF service. Also the callback address had to be passed by the client using CallbackContextMessageProperty and the workflow service had to use a callback correlation handle … Continue reading More Workflow 4 Services and duplex communications

There are quite a a few cases where it is useful to have a duplex communications. An obvious candidate is allowing a service to notify the user interface application of the progress so the user knows what is happening. Normally, when using plain WCF, you would use a ServiceContract attribute with a CallbackContract that specified the service uses duplex communications. For example something like the following code on the server: [ServiceContract(CallbackContract = typeof(IService1Callback))] public interface IService1 { [OperationContract] string GetData(int value); }   [ServiceContract] public interface IService1Callback { [OperationContract] void Reply(string message); } along with a client like this: class … Continue reading Workflow 4 Services and duplex communications