GRPC

Introduction

gRPC is a high-performance, open-source RPC framework that uses Protocol Buffers for serialization and HTTP/2 for transport. It enables efficient communication between services across different languages and platforms.

Message Types

Type	Client Sends	Server Responds	Use Case Example
Unary	Single request	Single response	Fetching user profile
Server Streaming	Single request	Stream of responses	Receiving a list of updates or logs
Client Streaming	Stream of requests	Single response	Uploading a batch of telemetry data
Bidirectional Streaming	Stream of requests	Stream of responses	Real-time chat or collaborative editing

Define Your Service, Messages

syntax = "proto3";

package dvdrental.v1;

import "google/protobuf/empty.proto";

option go_package = "git.bibble.co.nz/bibble235/grpc_server_go/pb;pb";

// Film represents a movie in the DVD rental system
message Film {
  // Unique identifier for the film
  string id = 1;
  // Title of the film
  string title = 2;
  // Description or synopsis of the film
  string description = 3;
  // Year the film was released
  string release_year = 4;
}

// Actor represents a person who acts in films
message Actor {
  // Unique identifier for the actor
  string id = 1;
  // First name of the actor
  string first_name = 2;
  // Last name of the actor
  string last_name = 3;
}

// ActorList contains multiple Actor records
message ActorList {
  // List of actors
  repeated Actor actor = 1;
}

// FilmList contains multiple Film records
message FilmList {
  // List of films
  repeated Film film = 1;
}

// FilmIdRequest is used to request a specific film by ID
message FilmIdRequest {
  // ID of the film to retrieve
  string id = 1;
}

// ActorIdRequest is used to request a specific actor by ID
message ActorIdRequest {
  // ID of the actor to retrieve
  string id = 1;
}

// DVDRentalService provides operations to interact with the DVD rental system
service DVDRentalService {
  // GetActor retrieves an actor by their ID
  rpc GetActor(ActorIdRequest) returns (Actor);
  
  // GetActorListWithStream streams all actors one by one
  rpc GetActorListWithStream(google.protobuf.Empty) returns (stream Actor);
  
  // GetActorListWithRepeated retrieves all actors in a single response
  rpc GetActorListWithRepeated(google.protobuf.Empty) returns (ActorList);

  // GetFilm retrieves a film by its ID
  rpc GetFilm(FilmIdRequest) returns (Film);
  
  // GetFilmListWithStream streams all films one by one
  rpc GetFilmListWithStream(google.protobuf.Empty) returns (stream Film);
  
  // GetFilmListWithRepeated retrieves all films in a single response
  rpc GetFilmListWithRepeated(google.protobuf.Empty) returns (FilmList);
}

Csharp

Lets start with a CSharp client

dotnet new console -n grpc_client_cs
cd grpc_client_cs
mkdir -p api/proto/v1

Add the dependencies

dotnet add package Grpc.Net.Client
dotnet add package Google.Protobuf
dotnet add package Grpc.Tools

Add the proto top the project.

  <ItemGroup>
    <Protobuf Include="api/proto/v1/dvdrental.proto" GrpcServices="Client" />
  </ItemGroup>

For basic client we have

using Grpc.Net.Client;
using Dvdrental.V1;
using Google.Protobuf.WellKnownTypes;

var channel = GrpcChannel.ForAddress("https://localhost:50051");
var client = new DVDRentalService.DVDRentalServiceClient(channel);

// Example: Get an actor by ID
var actorRequest = new ActorIdRequest { Id = "1" };
var actor = await client.GetActorAsync(actorRequest);

Console.WriteLine($"Actor: {actor.FirstName} {actor.LastName}");

// Example: Get all films (repeated)
var filmsResponse = await client.GetFilmListWithRepeatedAsync(new Empty());
foreach (var film in filmsResponse.Film)
{
    Console.WriteLine($"Film: {film.Title} ({film.ReleaseYear})");
}

Lets add oauth.

dotnet add package DotNetEnv
dotnet add package Microsoft.Extensions.Http
dotnet add package Microsoft.Extensions.Configuration
dotnet add package System.IdentityModel.Tokens.Jwt
dotnet add package Microsoft.Extensions.Configuration.Json