What is RPC? RPC means “remote procedure call”. The concept is called a remote function as a local function.

Then gRPC? It is a framework that helps you create RPC.

Traditional RPC has some problem making it hard to use. For example, how do you know, what type of message you get?

Usually, we use JSON or others format. But marshal & unmarshal quickly became a big issue. Because as time goes on, we don’t actually know which service use which field, thus we can’t reduce anything.

And server & client will get further farther for the same reason.

These all, won’t be an issue in gRPC.

In gRPC, you define a*.proto file for your service.

At here, we will create one namedUserService

syntax="proto3";packageuser;serviceUserService{rpcGetUser(Empty)returns(User){}}// define message typemessageEmpty{}messageUser{stringname=1;int32age=2;}

To generate code, I usually usego generate ./...

So let’s have a filegen.go, just leave a comment about what command you want to execute.

//go:generate sh -c "protoc -I./user --go_out=plugins=grpc:./user ./user/*.proto"

Implement service:

import"path/to/grpc_generated/user"typeUserServicestruct{}func(us*UserService)GetUser(ctxcontext.Context,u*user.Empty)(*user.User,error){return&user.UserName{Name:"Danny",Age:21,},nil}

Create server:

import("net""path/to/grpc_generated/user""google.golang.org/grpc")funcmain(){l,err:=net.Listen("tcp",":50051")// handle errserver:=grpc.NewServer()service:=user.UserServiceServer(&UserService{})user.RegisterUserServiceServer(server,service)err=server.Serve(l)// handle err}

Final is our client:

import("fmt""net""path/to/grpc_generated/user""google.golang.org/grpc")funcmain(){conn,err:=grpc.Dial("localhost:50051",grpc.WithInsercure())// handle errdeferconn.Close()client:=user.NewUserServiceClient(conn)u,err:=client.GetUser(context.Background(),&user.Empty{})// handle errfmt.Printf("Name: %s, Age: %d",u.Name,u.Age)}

After that, rungo generate ./... from project root dir.

Thengo run server.go, open another terminal,go run client.go

I usually won’t commit generated code(unless commit it makes sense), so I usually will write*.pb.go in file.gitignore

More info:

• grpc.io