现在grpc基本上用的都是proto3， 官网 style guide

示例如下：

需要重点掌握slice和map的用法以及rpc的定义

syntax = "proto3";

option go_package="./;proto";

service Greeter {
  rpc GetConfigFromVPS(Empty) returns (BMKConfig);
  rpc SendConfigToVPS(stream BMKConfig) returns (Empty); 
}

message BMKConfig {
  repeated Brand brands = 1;
  map<string,string> file_map = 2;
}

message Brand {
  string short_name = 1;
  string full_name = 2;
  string color = 3;
}

message Empty {
}

Scalar Value Types

A scalar message field can have one of the following types – the table shows the type specified in the .proto file, and the corresponding type in the automatically generated class: