Protobuf message / enum type rename and wire compatibility?

Question

Is it (practically) possible to change the type name of a protobuf message type (or enum) without breaking communications?

Obviously the using code would need to be adpated to re-compile. The question is if old clients that use the same structure, but the old names, would continue to work?

Example, base on the real file:

test.proto:

syntax = "proto3";
package test;
// ...

message TestMsgA {

  message TestMsgB { // should be called TestMsgZZZ going forward
    // ...
    enum TestMsgBEnum { // should be called TestMsgZZZEnum going forward
    // ...
    }

    TestMsgBEnum foo = 1;
    // ...
  }

  repeated TestMsgB bar = 1;
  // ...
}

Does the on-the-wire format of the protobuf payload change in any way if type or enum names are changed?

Answer 1

If you're talking about the binary format, then no: names don't matter and will not impact your ability to load data; For enums, only the integer value is stored in the payload. For fields, only the field-number is stored.

Obviously if you swap two names, confusion could happen, but: it should load as long as the structure matches.

If you're talking about the JSON format, then it may matter.