Question

I have several WCF service contracts, all of which contain exactly the same method StopOperation, having the same signature:

[ServiceContract]
public interface IMyServiceA
{
    [FaultContract(typeof(ServiceAError))]
    [OperationContract]
    void StopOperation(TaskInformation taskInfo);

    // other specific methods
}

What I’d like to be able to do is to extract StopOperation into an interface, IStoppable, and have all my services inherit this operation. However, I have a problem with the FaultContract definition, as it defines a concrete fault type.

Is it possible to have FaultContract refer to an abstract ErrorBase type, and have the concrete ones specified by KnownContract somehow? Kind of like:

[ServiceContract]
public interface IStoppable
{
    [FaultContract(typeof(ErrorBase))]
    [OperationContract]
    void StopOperation(TaskInformation taskInfo);
}

No matter where I tried specifying KnownContract, it didn’t seem to take.

Answer 1

Have you tried using a generic type ?

For instance:

[ServiceContract]
public interface IStoppable<T> where T : ErrorBase
{
    [FaultContract(typeof(T))]
    [OperationContract]
    void StopOperation(TaskInformation taskInfo);
}

Then you’d say

[ServiceContract]
public interface IMyServiceA : IStoppable<ServiceAError>
{
    // other specific methods
}

Haven’t tested this, but I don’t see any reason why this shouldn’t work.