title: Is it possible to use an interface type as parameter type in a WCF operation?
body: <p>There's some interface:</p>
  
  <pre><code>public interface IMessage
  {
      string Content;
      Person Sender;
  }
  
  public class Priv : IMessage
  {
      public string Content { get; set; }
      public Person Sender { get; set; }
      private int whatever;
  }
  
  public class Publ : IMessage
  {
      public string Content { get; set; }
      public Person Sender { get; set; }
      private DateTime something;
  }
  </code></pre>
  
  <p>Is it possible to use in wcf service <code>IMessage</code> instance? 
  Like <code>void SomeMethod(IMessage toSend)</code>?</p>