Async CTP - How can I use async/await to call a wcf service?

Question

If I call a WCF service method I would do something like this:

proxy.DoSomethingAsync();
proxy.DoSomethingAsyncCompleted += OnDoSomethingAsyncCompleted;
         


        

Answer 1

It is quite common to have asynchronous clients calling a synchronous service.
The following client and service contracts match (a bit magic used behind the scenes):

    [ServiceContract( Namespace="X", Name="TheContract" )]
    public interface IClientContractAsynchronous
    {
        [OperationContract]
        Task SendReceiveAsync( TRequest req );
    }

    [ServiceContract( Namespace="X", Name="TheContract" )]
    public interface IServiceContractSynchronous
    {
        [OperationContract]
        TResponse SendReceive( TRequest req );
    }

The client interface is directly awaitable:

   var response = await client.Channel.SendReceiveAsync( request );

It is not possible to use out or ref parameters in the operaton contract. All response data must be passed in the return value. This actually was a breaking change for me.
I use this interface in AsyncWcfLib, it supports a Actor based programming model.