proto_mismatch

mismatch proto files

Question

what will happen if proto files mismatch?

• rpc method name
• rpc request name
• rpc request parameter name
• rpc request parameter type

./proto/play.proto

...

service PlaySvc {
    rpc Play(PlayReq) returns (PlayRes){}
    rpc Stop(StopReq) returns (StopRes){}
}

message PlayReq {
    int64 Nums = 1;
    string Address = 2;
    int64 Count = 3;
}

...

./proto2/play.proto

...

service PlaySvc {
    rpc Play(PlayReq2) returns (PlayRes){}
    rpc Stop2(StopReq) returns (StopRes){}
}

message PlayReq2 {
    string A = 1;
    string Cat = 2;
    int64  Nums = 3;
}

...

Demo

1. start server

• server use ./proto

go run server/server.go

2. send request

• client use ./proto2

go run client/client.go

Mismatch explain

     --------                        ---------
    |        |                      |         |
    | sender |  ----> [bytes] ----> | receiver|
    |        |                      |         |
     --------                        ---------

• sender encode reqeust/response struct to protobuf bytes

  • protobuf dismiss attribute's name, encode with order number and type

• transport bytes

• receiver decode protobuf bytes to struct

  • decode by order and type
  • if types mismatch in the same order, save bytes into unknownFields and set corresponding attribute default value

protobuf

protobuf is just a serialization/deserialization tool (just like JSON)

Protobuf语法