Use Simple Values with gRPC in Go Microservices

Install Protocol Buffers

The latest release of Protocol Buffers can be found on the release page https://github.com/protocolbuffers/protobuf/releases/tag/v3.9.1

Install Libraries

Make sure Git is installed on your machine and in your system’s PATH. Install the package to your $GOPATH with the go tool from shell:

$ go get google.golang.org/grpc

Create Proto Service

Create new folder named src. In src folder, create new folder named addservice. In addservice folder, create new folder named proto. In proto folder, create new file named add.proto as below:

syntax = "proto3";

package addservice;

service AddService {
    rpc Add (AddRequest) returns (AddResponse);
}

message AddRequest {
    double a = 1;
    double b = 2;
}

message AddResponse {
    double result = 1;
}

Generate Protocol Buffers

Select addservice folder and open it in Terminal window of Visual Studio Code. Use command line as below to generate add.pb.go file:

protoc -I ./ proto/add.proto --go_out=plugins=grpc:.

Create Handlers

In addservice folder, create new folder named handlers. In this folder, create new file named handler.go as below:

package handlers

import (
	addservice "addservice/proto"
	"context"
)

type AddServiceServer struct {
}

func (*AddServiceServer) Add(ctx context.Context, in *addservice.AddRequest) (*addservice.AddResponse, error) {
	return &addservice.AddResponse{Result: in.A + in.B}, nil
}

Create Server

In addservice folder, create new folder named server. In this folder, create new file named main.go as below:

package main

import (
	"addservice/handlers"
	addservice "addservice/proto"
	"fmt"
	"net"
	"google.golang.org/grpc"
)

func main() {

	lis, err := net.Listen("tcp", ":1111")
	if err != nil {
		fmt.Println(err)
	}
	defer lis.Close()

	addServ := handlers.AddServiceServer{}
	grpcServer := grpc.NewServer()

	addservice.RegisterAddServiceServer(grpcServer, &addServ)

	if err := grpcServer.Serve(lis); err != nil {
		fmt.Println(err)
	}

}

Start Server

Select main.go file in server folder and open it in Terminal window of Visual Studio Code. Use command line as below to start server:

go run main.go

Create Client

In src folder, create new folder named client. In this folder, create new file named main.go as below:

package main

import (
	addservice "addservice/proto"
	"context"
	"fmt"
	"google.golang.org/grpc"
)

func main() {

	conn, err := grpc.Dial(
		"localhost:1111",
		grpc.WithInsecure(),
	)
	if err != nil {
		fmt.Println(err)
	}
	defer conn.Close()

	addServ := addservice.NewAddServiceClient(conn)

	response, err := addServ.Add(context.Background(), &addservice.AddRequest{A: 2, B: 5})
	if err != nil {
		fmt.Println(err)
	} else {
		result := response.Result
		fmt.Println("Result: ", result)
	}

}

Start Client

Select main.go file in client folder and open it in Terminal window of Visual Studio Code. Use command line as below to start client:

go run main.go

Output

Result: 7

Structure of Project