Go gRPC

Example of working with gRPC for Go based on a repository.

Usage

• download repository: git clone https://github.com/gocias/go-grpc
• go to the project: cd go-grpc/
• first terminal (server): go run server/main.go
• second terminal (client): go run client/main.go

General algorithm

• new functionality (change file) proto/helloworld.proto
• do recompiling
• add functionality to the server server/main.go
• add functionality processing to the client client/main.go

Explanations

In the proto file proto/helloworld.proto we create a new method:

// Sends something
rpc SaySomething (HelloRequest) returns (HelloReply) {}

In the server file server/main.go we implement the logic of the new method:

func (s *server) SaySomething(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
    return &pb.HelloReply{Message: "Say something here: " + in.GetName()}, nil
}

In the client file client/main.go we process the logic of the new method:

r, err = c.SaySomething(ctx, &pb.HelloRequest{Name: *name})
if err != nil {
    log.Fatalf("could not greet: %v", err)
}
log.Printf("Something: %s", r.GetMessage())

Where c is the connection pb.NewGreeterClient(conn), and pb is a link to the proto file at go-grpc/proto for the module gocias.ru/go-grpc. Import: pb "gocias.ru/go-grpc/proto"

Hints

Stop the server on port 50052.

sudo kill -9 `sudo lsof -t -i:50052`

Recompiling the updated .proto file.

protoc --go_out=. --go_opt=paths=source_relative \
    --go-grpc_out=. --go-grpc_opt=paths=source_relative \
    proto/helloworld.proto

Peculiarities

• use grpc.NewClient instead of grpc.Dial