Protocol Buffer Services

Internal

• Protocol Buffer Concepts
• API

Overview

Protocol Buffers can define services that use messages to exchange data.

A service is a set of endpoints, introduced by the rpc keyword, with different semantics that can be used to call into the service, by sending a request, and then receiving a response.

service SomeService {
  rpc SomeEndpoint(SomeRequest) returns (SomeResponse);
  rpc SomeOtherEndpoint(SomeOtherRequest) returns (SomeOtherResponse);
}

message SomeRequest {
  ...
}

message SomeResponse {
  ...
}

message SomeOtherRequest {
  ...
}

message SomeOtherResponse {
  ...
}

This is how you define an API.

The service and the client code is generated by a framework, and the preferred one is gRPC.

gRPC and Protocol Buffer Services

Example

.
├── go.mod
├── pkg
│    ├── main
│    │    └── main.go
│    ├── modelpb               # Generated
│    │    └── messages.pb.go   # Generated
│    └── servicepb             # Generated
│         └── services.pb.go   # Generated 
└── protobuf
     ├── modelpb
     │    └── messages.proto
     └── servicepb
          └── services.proto

services.proto:

syntax = "proto3";

option go_package = "./servicepb";
package servicepb;

import "modelpb/messages.proto";

service SomeService {
  rpc SomeEndpoint(modelpb.SomeRequest) returns (modelpb.SomeResponse);
}

messages.proto:

syntax = "proto3";

option go_package = "./modelpb";
package modelpb;

message SomeRequest {
  int32 id = 1;
  string payload = 2;
}

message SomeResponse {
  int32 id = 1;
  string payload = 2;
}

Code generation:

 protoc \
   --proto_path=./protobuf --go_out=./pkg \
     modelpb/messages.proto servicepb/services.proto