c# - Why can't my operation contracts in my wcf client take interfaces as parameters?

Question

I have a simple wcf Service Contract that works fine if I use the concrete implementations for the interfaces, but if I want to use the interfaces in the paramaters instead of the concrete classes, it gives me the error which I will display below.

Here is code:

[ServiceContract]
public interface IClientUserRegistration
{
    [OperationContract]
    void RegisterClientUser(ClientUser clientUser);

    [OperationContract]
    List<ClientUser> GetUsers();
}

If I replace ClientUser with IClientUser, the WCF Test Client says that RegisterClientUser operation is not supported because it uses the type System.Object. If I replace the return value of GetUsers with List, it says that this operation is not supported because it uses the type System.Object[]. Why does it give these errors?

The reason why I was trying to use IClientUser is that I could implement different user types that implement the IClientUser interface and pass them into RegisterClient, but if I am only able to pass ClientUser, then I have to create a bunch of RegisterClient overrides that take different types of Users.

Answer 1

SOAP has no concept of interfaces. That would tend to make deserialization difficult.