gRPC 服务器如何调用 REST 端点

Question

我目前是 gRPC 技术的新手，并且一直在阅读它。

我目前的理解是 gRPC 只是另一种协议，就像 REST 是一种协议一样。现在假设我启动了一个我希望客户端使用的 gRPC 服务器，但在该 gRPC 服务器中我希望能够从外部消费者 RESTful Apis 获取信息，（例如 https://developer.riotgames.com/api-methods/）那还有可能吗？

Answer 1

您需要使用 grcp-gateway 来生成在 go-grpc-tutorial thanks to phuongdo

上可用的代理完整代码

安装依赖：

$sudo apt install libprotobuf-dev

go get google.golang.org/grpc

go get -u github.com/golang/protobuf/{proto,protoc-gen-go}

go get -u github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway

定义服务，pb/service.proto:

syntax = "proto3";

option go_package = "echo";

package echo;

import "google/api/annotations.proto";

  //Message represents a simple message sent to the Echo service.

 message Message {

 string id = 1;

string msg = 2;
}


 //Echo service responds to incoming echo requests.

service EchoService {

  //Echo method receives a simple message and returns it.

   //The message posted as the id parameter will also be returned.

rpc Echo(Message) returns (Message) {

option (google.api.http) = {

    post: "/v1/example/echo/{id}/{msg}"
};
}
}

为服务器和客户端生成存根

$ protoc -I/usr/local/include -I. \
-I$GOPATH/src \
-I$GOPATH/src/github.com/grpc-ecosystem/grpc-
 gateway/third_party/googleapis \
 --go_out=google/api/annotations.proto=github.com/grpc-ecosystem/grpc-
 gateway/third_party/googleapis/google/api,plugins=grpc:. \
 pb/service.proto

和 reverse proxy 对于 REST API

$ protoc -I/usr/local/include -I. \
-I$GOPATH/src \
-I$GOPATH/src/github.com/grpc-ecosystem/grpc-
 gateway/third_party/googleapis \
--grpc-gateway_out=logtostderr=true:. \
pb/service.proto

server/server.go:

package main

import (
"flag"

"github.com/golang/glog"
pb "github.com/go-grpc-tutorial/pb"
"golang.org/x/net/context"
"google.golang.org/grpc"
"net"
)

// Implements of EchoServiceServer

type echoServer struct{}

func newEchoServer() pb.EchoServiceServer {
return new(echoServer)
}

func (s *echoServer) Echo(ctx context.Context, msg *pb.Message) 
 (*pb.Message, error) {
glog.Info(msg)
return msg, nil
}

func Run() error {
listen, err := net.Listen("tcp", ":50051")
if err != nil {
    return err
}
server := grpc.NewServer()
pb.RegisterEchoServiceServer(server, newEchoServer())
server.Serve(listen)
return nil
}

func main() {
flag.Parse()
defer glog.Flush()

if err := Run(); err != nil {
    glog.Fatal(err)
}
}

写其余api,server/server-rproxy.go:

package main

 import (
"flag"
"net/http"
"github.com/grpc-ecosystem/grpc-gateway/runtime"
"github.com/golang/glog"
pb "github.com/go-grpc-tutorial/pb"
"golang.org/x/net/context"
"google.golang.org/grpc"
 )

 var (
echoEndpoint = flag.String("echo_endpoint", "localhost:50051", 
"endpoint of EchoService")
 )

func RunEndPoint(address string, opts ...runtime.ServeMuxOption) 
 error {
ctx := context.Background()
ctx, cancel := context.WithCancel(ctx)
defer cancel()

mux := runtime.NewServeMux(opts...)
dialOpts := []grpc.DialOption{grpc.WithInsecure()}
err := pb.RegisterEchoServiceHandlerFromEndpoint(ctx, mux, *echoEndpoint, dialOpts)
if err != nil {
    return err
}

http.ListenAndServe(address, mux)
return nil
 }

func main() {
flag.Parse()
defer glog.Flush()

if err := RunEndPoint(":8080"); err != nil {
    glog.Fatal(err)
}
 }

构建客户端server/client.go:

 package main

import (
"log"
"os"

"golang.org/x/net/context"
"google.golang.org/grpc"
pb "github.com/go-grpc-tutorial/pb"
)

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

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.NewEchoServiceClient(conn)

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

最后运行服务器、客户端、休息和调用休息：

$ go run server/server.go

$ go run client/client.go


$go run server/server-rproxy.go

 $ curl -X POST "http://localhost:8080/v1/example/echo/1/PhuongDV"

1: https://github.com/phuongdo/go-grpc-tutorial 2: https://i.stack.imgur.com/C4s7s.png

Answer 2

是的，这是可能的。您可以从您自己的 gRPC 服务代码调用其他 API 和服务。

只需让您的客户端调用您的 gRPC 服务即可。然后，您的服务对外部 API 进行 REST 调用（可能使用从客户端请求到您的 gRPC 服务的参数）并处理它。 Return 无论您的 gRPC 服务如何响应，都会将结果发送给您的客户端。

gRPC 服务器如何调用 REST 端点

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