I know you can notify with
What if my receiver wants to know a little more than just a ping? I can be notified that a message has arrived. What if I also want to be notified with an integer that summarizes the message?
I thought of leaving the integer in a global place for receiver to fetch, but there's no promise the number they fetch hasn't been written over by the time they fetch it. I'd like a little more direct delivery to the receiver.