title: Passing Interface in a WCF Service?
body: <p>I'm experimenting with WCF Services, and have come across a problem with passing Interfaces.</p>
  
  <p>This works:</p>
  
  <pre><code>[ServiceContract]
  public interface IHomeService
  {
      [OperationContract]
      string GetString();
  }
  </code></pre>
  
  <p>but this doesn't:</p>
  
  <pre><code>[ServiceContract]
  public interface IHomeService
  {
      [OperationContract]
      IDevice GetInterface();
  }
  </code></pre>
  
  <p>When I try to compile the client it fails on the GetInterface method. I get an Exception saying that it can't convert Object to IDevice.</p>
  
  <p>On the clientside the IHomeService class correctly implements GetString with a string as it's returntype, but the GetInterface has a returntype of object. Why isn't it IDevice?</p>