examples

Hello World Example

Prerequisites

Install cmux

$ go get -u github.com/soheilhy/cmux

Download the example

$ go get google.golang.org/grpc

See here for more details.

Generate the HTTP server code

$ cd $GOPATH/src/google.golang.org/grpc/examples/helloworld
$ protoc helloworld/helloworld.proto --gohttp_out=pb_pkg_path=google.golang.org/grpc/examples/helloworld/helloworld:greeter_server
$ mv greeter_server/helloworld greeter_server/http

For those who want to preview the final generated code, see the pre-generated file helloworld.http.go.

Update the existing gRPC server code

$ cd $GOPATH/src/google.golang.org/grpc/examples/helloworld
$ vi greeter_server/main.go

1. Add the following imports:

   import (
   	...
   	"github.com/soheilhy/cmux"
   	"google.golang.org/grpc/examples/helloworld/greeter_server/http"
   	...
   )

2. Change the function main() as follows:

   func main() {
   	lis, err := net.Listen("tcp", port)
   	if err != nil {
   		log.Fatalf("failed to listen: %v", err)
   	}
   
   	m := cmux.New(lis)
   	// Using MatchWithWriters/SendSettings is a major performance hit (around 15%).
   	// Per the cmux documentation, you have to do this for grpc-java.
   	// If only using golang, you don't need this, but probably not
   	// great to assume what the calling languages are.
   	grpcL := m.MatchWithWriters(cmux.HTTP2MatchHeaderFieldPrefixSendSettings("content-type", "application/grpc"))
   	httpL := m.Match(cmux.Any())
   
   	srv := &server{}
   
   	// You can also set an unary server interceptor here
   	// For example:
   	//     httpS := http.NewServer(anUnaryServerInterceptor)
   	httpS := http.NewServer()
   	httpS.RegisterGreeterServer(srv)
   	go func() {
   		if err := httpS.Serve(httpL); err != nil {
   			log.Fatalf("failed to start HTTP server listening: %v", err)
   		}
   	}()
   
   	grpcS := grpc.NewServer()
   	pb.RegisterGreeterServer(grpcS, srv)
   	// Register reflection service on gRPC server.
   	reflection.Register(grpcS)
   	go func() {
   		if err := grpcS.Serve(grpcL); err != nil {
   			log.Fatalf("failed to serve: %v", err)
   		}
   	}()
   
   	m.Serve()
   }

Start the HTTP (and gRPC) server

$ cd $GOPATH/src/google.golang.org/grpc/examples/helloworld
$ go run greeter_server/main.go

Consume the HTTP service

By cURL:

$ curl -i -H 'Content-Type: application/json' -XPOST http://localhost:50051/greeter/say_hello -d '{"name": "world"}'

Or by HTTPie:

$ http post http://localhost:50051/greeter/say_hello name=world