What you might want to do is to use the callback system that is available in WCF Services. Since your callbacks can be on a different machine and not just locally, I think you would have a problem just putting the action in that way you had. You could setup something like this...
[ServiceContract(Name = "FeedbackService",
Namespace = "http://mycompany.com/FeedbackServices",
CallbackContract = typeof(IFeedbackAppProxyCallback),
SessionMode = SessionMode.Required)]
public interface IFeedbackAppProxy
public interface IFeedbackAppProxyCallback
[OperationContract(IsOneWay = true)]
void QuestionAnswered(Question q, Answer a);
Then in the implementation of the service for the subscribing you can add this...
public void Subscribe()
callback = OperationContext.Current.GetCallbackChannel<IFeedbackAppProxyCallback>();
public void Unsubscribe()
callback = null;
Then when you need to callback from the service you can just call...