# GRPC

## 官方网站

{% embed url="<https://grpc.io/>" %}

## 项目地址

{% embed url="<https://github.com/grpc/grpc-go>" %}

## 下载与安装

首先安装`protoc`

访问下方地址

{% embed url="<https://github.com/protocolbuffers/protobuf/releases>" %}

根据系统类型找到合适的安装包下载后解压，将其中的二进制文件移入`$PATH`目录中，将其中的`include/`目录下的文件复制到`/usr/local/lib/`目录下

接着安装 protoc-gen-go 插件

```bash
go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
```

最后下载 grpc 库

```bash
go get -u google.golang.org/grpc
```

如果无法访问外网则使用以下方式

```bash
git clone https://github.com/grpc/grpc-go.git $GOPATH/src/google.golang.org/grpc
git clone git@github.com:googleapis/go-genproto.git $GOPATH/src/google.golang.org/genproto
```

## 例子

### 简单grpc服务

{% tabs %}
{% tab title="server/main.go" %}

```go
package main

import (
	"context"
	"log"
	"net"

	"google.golang.org/grpc"
	
	"demo/rpc/grpc/simple/protos/pb"
)

const (
	port = "localhost:9090"
)

type server struct{}

func (s *server) Echo(ctx context.Context, in *pb.StringMessage) (*pb.StringMessage, error) {
	log.Printf("Received: %v", in.Value)
	return &pb.StringMessage{Value: "Hello " + in.Value}, nil
}

func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterYourServiceServer(s, &server{})
	if err := s.Serve(lis); err != nil {
		log.Fatalf("failed to serve: %v", err)
	}
}

```

{% endtab %}

{% tab title="client/main.go" %}

```go
package main

import (
	"context"
	"log"
	"os"
	"time"

	"google.golang.org/grpc"
	
	"demo/rpc/grpc/simple/protos/pb"
)

const (
	address     = "localhost:9090"
	defaultName = "world"
)

func main() {
	conn, err := grpc.Dial(address, grpc.WithInsecure())
	if err != nil {
		log.Fatalf("did not connect: %v", err)
	}
	defer conn.Close()
	c := pb.NewYourServiceClient(conn)

	name := defaultName
	if len(os.Args) > 1 {
		name = os.Args[1]
	}
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	r, err := c.Echo(ctx, &pb.StringMessage{Value: name})
	if err != nil {
		log.Fatalf("could not greet: %v", err)
	}
	log.Printf("Greeting: %s", r.Value)
}

```

{% endtab %}

{% tab title="protos/helloworld.proto" %}

```
syntax = "proto3";
option go_package = "/pb";

package example;

message StringMessage {
  string value = 1;
}

service YourService {
  rpc Echo(StringMessage) returns (StringMessage) {}
}
```

{% endtab %}
{% endtabs %}

执行命令

```
protoc --go_out=./protos --go-grpc_out=./protos --proto_path=./protos protos/*.proto
```

这时 protos/ 目录下会生成 helloworld.pb.go 和 helloworld\_grpc.pb.go 文件，该文件是 grpc 接口以及相关参数的定义

执行以下命令启动GRPC服务端

```bash
go run server/main.go
```

执行以下命令执行GRPC客户端

```
go run client/main.go
```

服务端输出

```
2019/06/25 17:32:09 Received: world
```

客户端输出

```
2019/06/25 17:32:09 Greeting: Hello world
```


---

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