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Comment by jeffbee

2 days ago

There is an art to having forwards and backwards compatible RPC schemas. It is easy, but it is surprisingly difficult to get people to follow easy rules. The rules are as follows:

  1) Never change the type of a field
  2) Never change the semantic meaning of a field
  3) If you need a different type or semantics, add a new field

Pretty simple if you ask me.

If I got to choose my colleagues this would be fine, unfortunately I had people who couldn’t understand eventual consistency. One of the guys writing Go admitted he didn’t understand what a pointer was etc. etc.

  • How does JSON protect you from that?

    • People understand JSON fairly commonly as they can see what is happening in a browser or any other system - what is the equivalent for GRPC if I want to do console.log(json)?

      GRPC for most people is a completely black box with unclear error conditions that are not as clear to me at least. For example what happens if I have an old schema and I'm not seeing a field, there's loads of things that can be wrong - old services, old client, even messages not being routed correctly due to networking settings in docker or k8s.

      Are you denying there is absolutely tones to learn here and it is trickier to debug and maintain?