Support request/response messaging

[FiniteReality]

Use case: I'd like to be able to say, for example, get me the latency of all servers in the eu region, and have singyeong figure out everything for me. This would be extremely useful for real-time monitoring or metrics for example, or even just service discovery for users. (E.g. a realm list in a MMORPG.)

As a workaround, you could configure some session ID (e.g. a GUID) as metadata and then say respond to [guid] with the latency for servers in the eu region. The latency would be returned as another query, e.g. send [x]ms to the server marked with session id [guid].

[queer]

Somewhat related: It would be convenient to have a way to run metadata queries without actually sending a message or something, just to be able to extract this sort of information more easily

[queer]

A subset of this would be some form of "send HTTP request to all these servers and aggregate responses," I think.

[queer]

At this point in time, there is no interest in pursuing this, primarily due to implementation not being clear how to implement properly in a distributed manner. I should revisit it in the future for sure.