gRPC server
- Go course
- Advanced
- Lesson 40/68
- 4 min
Learn to set up a gRPC server and register a service.
A gRPC server
The server writes a type that satisfies the generated interface, registers it with a grpc.Server and serves on a TCP listener:
type sunucu struct {
pb.UnimplementedSelamlayiciServer
}
func (sunucu) Selam(ctx context.Context, in *pb.SelamIstek) (*pb.SelamYanit, error) {
return &pb.SelamYanit{Mesaj: "Merhaba " + in.GetAd()}, nil
}
lis, _ := net.Listen("tcp", ":50051")
s := grpc.NewServer()
pb.RegisterSelamlayiciServer(s, sunucu{})
s.Serve(lis)Error codes
gRPC errors carry their own status codes instead of HTTP codes. The status package returns meaningful errors:
if in.GetAd() == "" {
return nil, status.Error(codes.InvalidArgument, "ad boş olamaz")
}The client reads the code with status.Code(err) and reacts to cases such as NotFound, Unauthenticated, DeadlineExceeded.
Practice A validating method
Write Selam(ad string) (string, error): if ad is empty return errors.New("ad boş olamaz"), otherwise "Merhaba " + ad. Print the error from Selam("").
Starter code
package main
import (
"errors"
"fmt"
)
func main() {
// buraya yaz
}Sample solution
package main
import (
"errors"
"fmt"
)
func Selam(ad string) (string, error) {
if ad == "" {
return "", errors.New("ad boş olamaz")
}
return "Merhaba " + ad, nil
}
func main() {
_, err := Selam("")
fmt.Println(err)
}Expected output
ad boş olamaz
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Why is <code>UnimplementedSelamlayiciServer</code> embedded?
- To speed up the server
- To enable TLS
- For logging
- So the code keeps compiling when new methods are added to the proto Correct answer
Explanation: The embedded type provides defaults that return an "Unimplemented" error for methods you haven't written; it is for forward compatibility.
2 Register the service
s := grpc.NewServer()
pb.____(s, sunucu{})s := grpc.NewServer()
pb.RegisterSelamlayiciServer(s, sunucu{})Explanation: The generated Register...Server function attaches the implementation to the server.
3 Server steps
| Term | Meaning |
|---|---|
net.Listen |
Opens a port |
grpc.NewServer |
Creates the server |
Register...Server |
Attaches the service |
s.Serve |
Serves requests |