I have to concur with Sean. The use of a switch statement to de-mux the mediator notifications takes me back to my early Windows programming days - and not in a good way. I agree that a mediator should be a "get in, get out" type of object, but the case statement has a "smell" to it for me. If you can have a hardcoded callback (handleNotification), you can have a customized callback. Internally, I think it requires one additional level of indirection more than what's there now. From an API perspective I'd prefer to see a registerNotificationInterest( noteName, callbackMethod) type method.