I just realized something important. The BoundedByteBufferSend comment above is not in sync with my original question. I was asking about Responses -- meaning, can I multiplex off a single socket, and when reading an arbitrary response, switch on request_id to the right handler?
In the blocking console sync client (which is the only trivial way to follow the code that I've found -- please enlighten if there's an async thing I can easily trace), this is a non issue, since you request, wait, parse expected response. Or do I need instead to just open separate sockets? (Not a big deal, but nice to understand clearly.) ben