Question

I’m protyping an application with WCF and I’m trying to define a Callback
Contract with an interface that derives from another one.
Doing so, the generated proxy code (using svcutil.exe) does not see the base
interface and a “NotSupportedException” is thrown on the Server when trying
to call methods defined in base interface.

I have also tried to manually define the base interface in the proxy class
so as to be able to implement the methods in the client -> Same behavior.

Does anyone knows why it does not work?

Thanks for any help and sorry for the repost!

Here is my contract definition :

namespace wcfContract
{

    [ServiceContract(Namespace = "Test")]
    public interface IPing
    {
        [OperationContract]
        void Ping();
    }

    public interface ITestCallback : IPing      
    //<-------------- IPing method not seen  at all in proxy
    {
        [OperationContract]
        void TestCB();
    }

    [ServiceContract(Namespace = "Test", CallbackContract =
        typeof(ITestCallback))]
    public interface ITest : IPing
    {
        [OperationContract]
        void Test();
    }
}

Answer 1

You’ll need to add the [ServiceContract] attribute to the ITestCallback interface.

[ServiceContract]
public interface ITestCallback : IPing
{
    [OperationContract]
    void TestCB ();
}

The service class needs to inherit the derived contract (ie. ITestCallback).

public class Service1 : ITestCallback
{
    ...
}

The corresponding endpoint binding in the Web.config file needs to specify the correct contract (as in the endpoint address for “ws” below).

<services>
  <service name="WcfService.Service1" behaviorConfiguration="WcfService.Service1Behavior">
    <!-- ITestCallback needs to be the contract specified -->
    <endpoint address="ws" binding="wsHttpBinding" contract="WcfService.ITestCallback">
    </endpoint>
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
  </service>
</services>

This worked for me; hope it works for you. I didn’t use the svcutil, I just referenced by adding a service reference in a project.