[dekhn]

Yes, I know all of this. I never saw IORs as a truly necessary feature, although I see the attractiveness of the idea. I'm sure you could, if you desired, implement IOR-like behavor on top of other RPC systems.

I never really had problems with message versioning because I owned the client and server, and created new messages when I wanted new versions.

[lobster_johnson]

Protobuf-style versioning gets pretty useful when you're developing microservices — where there are potentially a whole bunch of apps that would otherwise have to be upgraded at the exact same time, even for adding optional fields.