目录
- 1. Unary RPC
 - 2. Server-side streaming RPC
 - 3. Client-side streaming RPC
 - 4. Bidirectional streaming RPC
 - 4. ALTS
 - 4.1 ALTS的介绍
 - 4.2 gRPC客户端使用ALTS传输安全协议
 - 4.3 Server Authorization
 - 总结
 
本博客需要你有一点基本的gRPC的常识,如果你完全是新手建议访问官网全面了解。
1. Unary RPC
proto文件如下
syntax = "proto3";
option go_package=".;service";
message HelloRequest {
  // Name of the person to greet
  string name = 1;
}
message HelloResponse {
  // Greeting message
  string greeting = 1;
}
service HelloService {
  // RPC method to say hello
  rpc SayHello (HelloRequest) returns (HelloResponse){}
}
使用命令(注意命令路径和自己的对应):
protoc -I . --go-grpc_out=require_unimplemented_servers=false:. --go_out=. *.proto
对应目录上有xx.pb.go和xx_grpc.pb.go然后对应目录实现服务端接口
package main
import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"net"
	"test_grpc/service"
)
type HelloService struct {
}
func (hs *HelloService) SayHello(ctx context.Context, req *service.HelloRequest) (*service.HelloResponse, error) {
	resp := &service.HelloResponse{
		Greeting: fmt.Sprintf("hello %s --from Golang Server", req.Name),
	}
	return resp, nil
}
func main() {
	// listen on 127.0.0.1:50051
	listen, err := net.Listen("tcp", "127.0.0.1:50051")
	if err != nil {
		fmt.Println("Error happened when listen on 127.0.0.1:50051:", err)
		return
	}
	// grpc server
	s := grpc.NewServer()
	// register HelloService in grpc server
	service.RegisterHelloServiceServer(s, &HelloService{})
	// start rpc server
	fmt.Println("Golang rpc server is waiting messages......")
	if err = s.Serve(listen); err != nil {
		fmt.Println("Error happened when start rpc server:", err)
		return
	}
}
客户端接口如下:
package main
import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"test_grpc/service"
	"time"
)
func main() {
	// connect to server
	conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		fmt.Println("Connect to rpc server err:", err)
		return
	}
	defer conn.Close()
	// init service client
	c := service.NewHelloServiceClient(conn)
	// init context with timeout
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	// send message
	req := &service.HelloRequest{Name: "Golang"}
	r, err := c.SayHello(ctx, req)
	if err != nil {
		fmt.Println("Send message err:", err)
		return
	}
	fmt.Println("Client:", r.Greeting)
}
实际上为了更好得感受gRPC这种跨语言调用的感觉,可以尝试使用python编写client端代码,直接复制proto文件,在python中使用以下命令生成对应的proto文件(注意命令和自己的对应):
python -m grpc_tools.protoc -I . --python_out=. --pyi_out=. --grpc_python_out=. *.proto
使用python实现的客户端代码如下:
# client template
# grpc server address
channel = grpc.insecure_channel("127.0.0.1:50051")
stub = hello_pb2_grpc.HelloServiceStub(channel)
# send request
response = stub.SayHello(hello_pb2.HelloRequest(name="Python"))
print(response.greeting)
# hello Python --from Golang Server
2. Server-side streaming RPC
重新给出这个的proto文件,服务端将以流式数据的形式发送给客户端数据
syntax = "proto3";
option go_package=".;service";
message HelloRequest {
  // Name of the person to greet
  string name = 1;
}
message HelloResponse {
  // Greeting message
  string greeting = 1;
}
service HelloService {
  // RPC method to say hello
  rpc SayHello (HelloRequest) returns (stream HelloResponse){}
}
同理,生成对应的proto文件后,在对应的文件先生成server端的代码:
package main
import (
	"fmt"
	"google.golang.org/grpc"
	"net"
	"test_grpc/service"
)
type HelloService struct {
}
func (hs *HelloService) SayHello(req *service.HelloRequest, stream service.HelloService_SayHelloServer) error {
	resp := &service.HelloResponse{
		Greeting: fmt.Sprintf("hello %s --from Golang Server", req.Name),
	}
	// 连续发送5次
	for i := 0; i < 5; i++ {
		if err := stream.Send(resp); err != nil {
			return err
		}
	}
	return nil
}
func main() {
	// listen on 127.0.0.1:50051
	listen, err := net.Listen("tcp", "127.0.0.1:50051")
	if err != nil {
		fmt.Println("Error happened when listen on 127.0.0.1:50051:", err)
		return
	}
	// grpc server
	s := grpc.NewServer()
	// register HelloService in grpc server
	service.RegisterHelloServiceServer(s, &HelloService{})
	// start rpc server
	fmt.Println("Golang rpc server is waiting messages......")
	if err = s.Serve(listen); err != nil {
		fmt.Println("Error happened when start rpc server:", err)
		return
	}
}
同理给出客户端的代码:
package main
import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"io"
	"log"
	"test_grpc/service"
	"time"
)
func main() {
	// connect to server
	conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		fmt.Println("Connect to rpc server err:", err)
		return
	}
	defer conn.Close()
	// init service client
	c := service.NewHelloServiceClient(conn)
	// init context with timeout
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	// send message
	req := &service.HelloRequest{Name: "Golang"}
	stream, err := c.SayHello(ctx, req)
	if err != nil {
		fmt.Println("Send message err:", err)
		return
	}
	// 加载消息
	for {
		resp, err := stream.Recv()
		// 读到结束标志
		if err == io.EOF {
			log.Fatalf("end.....")
			break
		}
		if err != nil {
			log.Fatalf("failed to receive response: %v", err)
		}
		log.Printf("Greeting: %s", resp.Greeting)
	}
}
3. Client-side streaming RPC
对应的proto文件如下
syntax = "proto3";
option go_package=".;service";
message HelloRequest {
  // Name of the person to greet
  string name = 1;
}
message HelloResponse {
  // Greeting message
  string greeting = 1;
}
service HelloService {
  // RPC method to say hello
  rpc SayHello (stream HelloRequest) returns (HelloResponse){}
}
同理使用protoc命令生成对应的proto文件,后先编写client端的代码,如下:
package main
import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"log"
	"test_grpc/service"
	"time"
)
func main() {
	// connect to server
	conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		fmt.Println("Connect to rpc server err:", err)
		return
	}
	defer conn.Close()
	// init service client
	c := service.NewHelloServiceClient(conn)
	// init context with timeout
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	// create stream
	stream, err := c.SayHello(ctx)
	if err != nil {
		log.Fatalf("could not greet: %v", err)
	}
	names := []string{"World", "Gophers", "Anthropic"}
	for _, name := range names {
		// request body
		req := &service.HelloRequest{Name: name}
		if err := stream.Send(req); err != nil {
			log.Fatalf("faild to send request: %v", err)
		}
	}
	resp, err := stream.CloseAndRecv()
	if err != nil {
		log.Fatalf("%v.CloseAndRecv() got error %v, want %v", stream, err, nil)
	}
	log.Printf("Greeting: %s", resp.Greeting)
}
对应得完成服务端的代码:
package main
import (
	"fmt"
	"google.golang.org/grpc"
	"io"
	"net"
	"strings"
	"test_grpc/service"
)
type HelloService struct {
}
func (hs *HelloService) SayHello(stream service.HelloService_SayHelloServer) error {
	var strs []string
	for {
		msg, err := stream.Recv()
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		strs = append(strs, msg.Name)
	}
	resp := &service.HelloResponse{Greeting: strings.Join(strs, " ")}
	err := stream.SendAndClose(resp)
	if err != nil {
		return err
	}
	return nil
}
func main() {
	// listen on 127.0.0.1:50051
	listen, err := net.Listen("tcp", "127.0.0.1:50051")
	if err != nil {
		fmt.Println("Error happened when listen on 127.0.0.1:50051:", err)
		return
	}
	// grpc server
	s := grpc.NewServer()
	// register HelloService in grpc server
	service.RegisterHelloServiceServer(s, &HelloService{})
	// start rpc server
	fmt.Println("Golang rpc server is waiting messages......")
	if err = s.Serve(listen); err != nil {
		fmt.Println("Error happened when start rpc server:", err)
		return
	}
}
4. Bidirectional streaming RPC
新的proto文件被如下给出:
syntax = "proto3";
option go_package=".;service";
message HelloRequest {
  // Name of the person to greet
  string name = 1;
}
message HelloResponse {
  // Greeting message
  string greeting = 1;
}
service HelloService {
  // RPC method to say hello
  rpc SayHello (stream HelloRequest) returns (stream HelloResponse){}
}
和上文中的操作一致,同时给出server端的代码:
package main
import (
	"fmt"
	"google.golang.org/grpc"
	"io"
	"log"
	"net"
	"test_grpc/service"
)
type HelloService struct {
}
func (hs *HelloService) SayHello(stream service.HelloService_SayHelloServer) error {
	for {
		msg, err := stream.Recv()
		if err == io.EOF {
			break
		}
		if err != nil {
			return err
		}
		name := msg.Name
		resp := &service.HelloResponse{Greeting: name}
		if err = stream.Send(resp); err != nil {
			log.Fatalf("Failed to send a resp:%s", err)
		}
	}
	return nil
}
func main() {
	// listen on 127.0.0.1:50051
	listen, err := net.Listen("tcp", "127.0.0.1:50051")
	if err != nil {
		fmt.Println("Error happened when listen on 127.0.0.1:50051:", err)
		return
	}
	// grpc server
	s := grpc.NewServer()
	// register HelloService in grpc server
	service.RegisterHelloServiceServer(s, &HelloService{})
	// start rpc server
	fmt.Println("Golang rpc server is waiting messages......")
	if err = s.Serve(listen); err != nil {
		fmt.Println("Error happened when start rpc server:", err)
		return
	}
}
同时给出下面的client端的代码:
package main
import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	"io"
	"log"
	"test_grpc/service"
	"time"
)
func main() {
	// connect to server
	conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		fmt.Println("Connect to rpc server err:", err)
		return
	}
	defer conn.Close()
	// init service client
	c := service.NewHelloServiceClient(conn)
	// init context with timeout
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	// create stream
	stream, err := c.SayHello(ctx)
	if err != nil {
		log.Fatalf("could not greet: %v", err)
	}
	names := []string{"World", "Gophers", "Anthropic"}
	waitc := make(chan struct{})
	go func() {
		for {
			resp, err := stream.Recv()
			if err == io.EOF {
				close(waitc)
				return
			}
			if err != nil {
				log.Fatalf("%v.CloseAndRecv() got error %v, want %v", stream, err, nil)
			}
			log.Printf("Greeting: %s", resp.Greeting)
		}
	}()
	go func() {
		for _, name := range names {
			// request body
			req := &service.HelloRequest{Name: name}
			if err := stream.Send(req); err != nil {
				log.Fatalf("faild to send request: %v", err)
			}
			// send delay
			time.Sleep(1)
		}
		// 发送结束的消息
		if err := stream.CloseSend(); err != nil {
			log.Fatalf("failed to close stream: %v", err)
		}
	}()
	<-waitc
}
一定要注意关闭发送或者避免针对一个已经关闭stream进行发送消息,读取消息是被允许的,这里有一点类似chan
4. ALTS
4.1 ALTS的介绍
应用层传输安全(ALTS)是谷歌开发的一种相互验证和传输加密系统。它用于确保谷歌基础设施内 RPC 通信的安全。ALTS 类似于相互 TLS,但经过设计和优化,可满足 Google 生产环境的需要。ALTS在gRPC中有以下的特征:
- 使用ALTS作为传输协议创建gRPC的服务端和客户端;
 - ALSTS是一个端到端的保护,具有隐私性和完成性;
 - 应用可以访问对等信息比如对等服务账户;
 - 支持客户端和服务端的认知;
 - 最小的代码更改就能使用ALTS;
 
值得注意的是ALTS被全部发挥作用如果应用程序运行在CE或者GKE中
4.2 gRPC客户端使用ALTS传输安全协议
gRPC客户端使用ALTS认证去连接服务端,正如下面代码中所描述的:
import (
  "google.golang.org/grpc"
  "google.golang.org/grpc/credentials/alts"
)
altsTC := alts.NewClientCreds(alts.DefaultClientOptions())
// connect to server
conn, err := grpc.Dial("127.0.0.1:50051", grpc.WithTransportCredentials(altsTC))
gRPC服务端能够使用ALTS认证来运行客户端连接到它,正如下面的描述:
import ( "google.golang.org/grpc" "google.golang.org/grpc/credentials/alts" ) altsTC := alts.NewServerCreds(alts.DefaultServerOptions()) server := grpc.NewServer(grpc.Creds(altsTC))
4.3 Server Authorization
gRPC 内置了使用 ALTS 的服务器授权支持。使用 ALTS 的 gRPC 客户端可以在建立连接前设置预期的服务器服务账户。然后,在握手结束时,服务器授权会保证服务器身份与客户端指定的服务账户之一相匹配。否则,连接将失败。
import (
  "google.golang.org/grpc"
  "google.golang.org/grpc/credentials/alts"
)
clientOpts := alts.DefaultClientOptions()
clientOpts.TargetServiceAccounts = []string{expectedServerSA}
altsTC := alts.NewClientCreds(clientOpts)
conn, err := grpc.Dial(serverAddr, grpc.WithTransportCredentials(altsTC))

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