Creating a simple hello world with gRPC

To understand the gRPC-Gateway we are going to first make a hello world gRPC service.

Defining your gRPC service using protocol buffers

Before we create a gRPC service, we should create a proto file to define what we need, here we create a file named hello_world.proto in the directory proto/helloworld/hello_world.proto.

The gRPC service is defined using Google Protocol Buffers. To learn more about how to define a service in a .proto file see their Basics tutorial. For now, all you need to know is that both the server and the client stub have a SayHello() RPC method that takes a HelloRequest parameter from the client and returns a HelloReply from the server, and that the method is defined like this:

  1. syntax = "proto3";
  3. package helloworld;
  5. // The greeting service definition
  6. service Greeter {
  7.   // Sends a greeting
  8.   rpc SayHello (HelloRequest) returns (HelloReply) {}
  9. }
  11. // The request message containing the user's name
  12. message HelloRequest {
  13.   string name = 1;
  14. }
  16. // The response message containing the greetings
  17. message HelloReply {
  18.   string message = 1;
  19. }

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