C#: What is gRPC and how does it work in .NET?

1syntax = "proto3";
2package greeter;
3
4service Greeter {
5    rpc SayHello (HelloRequest) returns (HelloReply);
6}
7
8message HelloRequest { string name = 1; }
9message HelloReply { string message = 1; }

1builder.Services.AddGrpc();
2app.MapGrpcService<GreeterService>();
3
4public class GreeterService : Greeter.GreeterBase
5{
6    public override Task<HelloReply> SayHello(
7        HelloRequest request, ServerCallContext context)
8    {
9        return Task.FromResult(
10            new HelloReply { Message = $"Hello {request.Name}" });
11    }
12}