WCF Dos and Don'ts

Do not inherit interfaces from other interfaces.

Interfaces are contracts. Contracts must be explicit, otherwise the flexibility and maintainability of your design would run into issues. An interface is a pure contract definition and should remain explicit and pure.

Consider the following example:
[ServiceContract]
public interface IMyService1
{

[OperationContract]

void Test1();

}

[ServiceContract]
public interface IMyService2 : IMyService1

{

[OperationContract]

void Test2();

}

[ServiceBehavior(…)]
class MyService : IMyService2, IMyService1

{

#region IMyService2 Members
public void Test2(){

}
#endregion
#region IMyService1 Members

public void Test1()

{

}
#endregion

}
What happens when you Publish your Service and open its communication channels. If you do the following:
ServiceHost serviceHost = new ServiceHost(typeof(MyService, …)ServiceEndpoint ep = serviceHost.AddServiceEndpoint(typeof(IMyService1), typeof(IMyService2));
You will get a nasty ambiguous message from WCF since you are trying to register the same contract twice; once implicitly with IMyService2 wince it inherits from IService1 and another time explicitly using IService1
In this case, you need to either do #1 (Still the wrong way) or #2(the right way)
#1: remove the IMyService1 from both the Service inheritance and implicitly implement IMyService1’s operation contracts and remove the IMyService1 from your service endpoints registration with WCF.

[ServiceBehavior(…)]
class MyService : IMyService2
{

#region IMyService2 Members
public void Test2()
{
}
#endregion
#region IMyService1 Members

void IMyService1.Test1()
{

}

#endregion

}

ServiceHost serviceHost = new ServiceHost(typeof(MyService, …)
ServiceEndpoint ep = serviceHost.AddServiceEndpoint(typeof(IMyService2));

In this case it is very ambiguous to anyone reading the code to know at a glance that your service publishes an IMyService1 as a service contract


#2 (the right way)

Just remove the inheritance of IMyService1 from iMyService2’s interface. That’s it.[ServiceContract]

public interface IMyService2

{

[OperationContract]

void Test2();

}