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 productservice. In productservice folder, create new folder named proto. In proto folder, create new file named product.proto as below:
syntax = "proto3";
package productservice;
service ProductService {
rpc FindAll (FindAllRequest) returns (FindAllResponse);
rpc Search(SearchRequest) returns (SearchResponse);
}
message SearchRequest {
string keyword = 1;
}
message SearchResponse {
repeated Product Products = 1;
}
message FindAllRequest {
}
message FindAllResponse {
repeated Product Products = 1;
}
message Product {
string id = 1;
string name = 2;
int32 quantity = 3;
double price = 4;
bool status = 5;
}
Generate Protocol Buffers
Select productservice folder and open it in Terminal window of Visual Studio Code. Use command line as below to generate product.pb.go file:
protoc -I ./ proto/product.proto --go_out=plugins=grpc:.
Create Handlers
In productservice folder, create new folder named handlers. In this folder, create new file named handler.go as below:
package handlers
import (
"context"
productservice "productservice/proto"
"strings"
)
type ProductServiceServer struct {
}
var products []*productservice.Product
func init() {
products = []*productservice.Product{
&productservice.Product{
Id: "p01",
Name: "tivi 1",
Price: 4.5,
Quantity: 4,
Status: true,
},
&productservice.Product{
Id: "p02",
Name: "tivi 2",
Price: 22,
Quantity: 3,
Status: false,
},
&productservice.Product{
Id: "p03",
Name: "laptop 3",
Price: 27,
Quantity: 3,
Status: true,
},
}
}
func (*ProductServiceServer) FindAll(ctx context.Context, in *productservice.FindAllRequest) (*productservice.FindAllResponse, error) {
return &productservice.FindAllResponse{Products: products}, nil
}
func (*ProductServiceServer) Search(ctx context.Context, in *productservice.SearchRequest) (*productservice.SearchResponse, error) {
var result []*productservice.Product
for _, product := range products {
if strings.Contains(product.Name, in.Keyword) {
result = append(result, product)
}
}
return &productservice.SearchResponse{Products: result}, nil
}
Create Server Interceptors
In productservice folder, create new folder named interceptors. In this folder, create new server interceptors as below:
DateLog Interceptor
In interceptors folder, create new go file named dateloginterceptor.go as below:
package interceptors
import (
"context"
"fmt"
"time"
"google.golang.org/grpc"
)
func DateLogInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
today := time.Now()
fmt.Println("Access product service date: " + today.Format("01/02/2006 15:04:05"))
return handler(ctx, req)
}
MethodLog Interceptor
In interceptors folder, create new go file named methodloginterceptor.go as below:
package interceptors
import (
"context"
"fmt"
"google.golang.org/grpc"
)
func MethodLogInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
fmt.Println("Method: ", info.FullMethod)
return handler(ctx, req)
}
Create Server
In productservice folder, create new folder named server. In this folder, create new file named main.go as below:
package main
import (
"fmt"
"net"
"productservice/handlers"
"productservice/interceptors"
productservice "productservice/proto"
grpc_middleware "github.com/grpc-ecosystem/go-grpc-middleware"
"google.golang.org/grpc"
)
func main() {
lis, err := net.Listen("tcp", ":1111")
if err != nil {
fmt.Println(err)
}
defer lis.Close()
s := handlers.ProductServiceServer{}
server := grpc.NewServer(
grpc.UnaryInterceptor(
grpc_middleware.ChainUnaryServer(
interceptors.DateLogInterceptor,
interceptors.MethodLogInterceptor,
),
),
)
productservice.RegisterProductServiceServer(server, &s)
if err := server.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 (
"context"
"fmt"
productservice "productservice/proto"
"google.golang.org/grpc"
)
func main() {
conn, err := grpc.Dial(
"localhost:1111",
grpc.WithInsecure(),
)
if err != nil {
fmt.Println(err)
}
defer conn.Close()
productServ := productservice.NewProductServiceClient(conn)
response1, err1 := productServ.FindAll(context.Background(), &productservice.FindAllRequest{})
if err1 != nil {
fmt.Println(err1)
} else {
products := response1.Products
fmt.Println("Product List")
for _, product := range products {
fmt.Println("id: ", product.Id)
fmt.Println("name: ", product.Name)
fmt.Println("price: ", product.Price)
fmt.Println("quantity: ", product.Quantity)
fmt.Println("status: ", product.Status)
fmt.Println("========================")
}
}
response2, err2 := productServ.Search(context.Background(), &productservice.SearchRequest{Keyword: "vi"})
if err2 != nil {
fmt.Println(err2)
} else {
products := response2.Products
fmt.Println("Search Products")
for _, product := range products {
fmt.Println("id: ", product.Id)
fmt.Println("name: ", product.Name)
fmt.Println("price: ", product.Price)
fmt.Println("quantity: ", product.Quantity)
fmt.Println("status: ", product.Status)
fmt.Println("========================")
}
}
}
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
Server’s Output
Access product service date: 08/19/2019 16:01:55
Method: /productservice.ProductService/FindAll
Access product service date: 08/19/2019 16:01:55
Method: /productservice.ProductService/Search
Client’s Output
Product List
id: p01
name: tivi 1
price: 4.5
quantity: 4
status: true
========================
id: p02
name: tivi 2
price: 22
quantity: 3
status: false
========================
id: p03
name: laptop 3
price: 27
quantity: 3
status: true
========================
Search Products
id: p01
name: tivi 1
price: 4.5
quantity: 4
status: true
========================
id: p02
name: tivi 2
price: 22
quantity: 3
status: false
========================
Structure of Project
