I need to generate caller-specific results on the callee side. My original move was to maintain per-caller states there and to use caller IDs for selecting corresponding contexts. However, I can't see how I can obtain a caller's ID from the body of a registered function. The context is about to be quite big, so I don't want to pass it around on every call. At the same time, passing the ID as an extra parameter looks like an insecure solution.
Am I missing something?