# grpc-go 的安装和使用

简单来讲 gRPC 是一个 基于 HTTP/2 协议设计的 RPC 框架，它采用了 Protobuf 作为 IDL (接口定义语言)

### grpc-go 安装

1. 使用 go get 安装代码库

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

2. 安装 protocol buffers v3 mac os 下使用 homebrew 安装

```sh
  brew install automake
  brew install libtool
  brew install protobuf
```

3. 安装针对Go语言的代码生成插件

```sh
go get -u github.com/golang/protobuf/protoc-gen-go
```

4. 加入到PATH路径

```sh
export PATH=$PATH:$GOPATH/bin
```

5. 编写 .proto 文件

```sh
vim helloworld.proto
```

```go
syntax = "proto3";

package protos;
// The greeting service definition.
service Hello {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

```

6. 编译 .proto 文件

```sh
protoc --go_out=plugins=grpc:. *.proto
//或
protoc --gofast_out=plugins=grpc:. *.proto

protoc -I hello/ hello/protos/hello.proto --go_out=plugins=grpc:hello
```

### **官方 example 运行**

server.go 建立

```go
package main

import (
    "log"
    "net"

    "golang.org/x/net/context"
    "google.golang.org/grpc"
    pb "go-server/app/rpc/hello/protos"
    "google.golang.org/grpc/reflection"
)

const (
    port = ":50051"
)

// server is used to implement helloworld.GreeterServer.
type server struct{}

// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

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

**client 建立**

```go
package main

import (
    "log"
    "os"

    "golang.org/x/net/context"
    "google.golang.org/grpc"
    pb "go-server/app/rpc/hello/protos"
)

const (
    address     = "localhost:50051"
    defaultName = "world"
)

func main() {
    // Set up a connection to the server.
    conn, err := grpc.Dial(address, grpc.WithInsecure())
    if err != nil {
        log.Fatalf("did not connect: %v", err)
    }
    defer conn.Close()
    c := pb.NewHelloClient(conn)

    // Contact the server and print out its response.
    name := defaultName
    if len(os.Args) > 1 {
        name = os.Args[1]
    }
    r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: name})
    if err != nil {
        log.Fatalf("could not greet: %v", err)
    }
    log.Printf("Greeting: %s", r.Message)
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://go.codetrue.net/packages/installation-and-use-of-grpc-go.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.