1. protoc --go_out=. test.proto

2. .proto => .pb.gos

3. option go_package = "github.com/golang/protobuf/p"; instead of package example;

1. protoc --go_out=. example/test.proto
2. protoc --go_out=paths=source_relative:. example/test.prot-o

[Note] paths=[import|source_relative]

Attention!!! --proto_path=<> is very useful e.g. protoc --proto_path=example --go_out=pkg test.proto

4. If a proto file specifies RPC services, protoc-gen-go can be instructed to generate code compatible with gRPC protoc --go_out=plugins=grpc,paths=source_relative:. example/test.proto

[Note] plugins=grpc

5. For grpc service

1. For client, define interface and implement those functions
2. For server, only define interface BTW, there is register function like 'RegisterAPIServiceServer'

6. create client and server

1. client conn, err := grpc.Dial(*address, grpc.WithInsecure()) // *grpc.ClientConn defer conn.Close()

c := v1.NewToDoServiceClient(conn)

ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second) defer cancel() [Note] ctx is used to call server function

2. server server := grpc.NewServer() v1.RegisterToDoServiceServer(server, v1API)

listen, err := net.Listen("tcp", ":"+port) server.Serve(listen)

7. HTTP <=> GRPC using github.com/grpc-ecosystem/grpc-gateway protoc --proto_path=api/proto/v1 --proto_path=third_party --grpc-gateway_out=logtostderr=true:pkg/api/v1 todo-service.proto