gRPC for .NET: Creating a gRPC Server Application

Follow this tutorial for a step-by-step guide to creating a gRPC server application that can aid in inter-service communication.

Kapil Khandelwal

Sep. 28, 21 · Tutorial

Likes (2)

Comment

Save

20.1K Views

While working with Protobuf message format for one of my client projects, I recently came across a gRPC framework. After doing my analysis, gRPC seems pretty promising for inter-service communication, particularly in microservices architectures. gRPC is a language-agnostic, high-performance Remote Procedure Call (RPC) framework.

gRPC is built on top of the HTTP/2 transport layer and therefore can support four types of gRPC methods (unary, client streaming, server streaming, and bi-directional streaming). It uses Protobuf for message exchange.

In this post, I will be explaining how we can quickly set up a gRPC Server Application.

Getting Started With gRPC Server Application

Step 1: Add a New Project

Go to gRPC Server Project File/Folder Organization and pick the Asp.net Core gRPC service project template in Visual Studio.

Step 2: Add CommandProcessor.proto in the Protos Root Folder

CommandProcessor.proto contains the following gRPC method types are:

Unary
Server streaming
Client streaming
Bi-directional streaming

     ProtoBuf 
   
 
 
   syntax = "proto3";

option csharp_namespace = "SampleApplication.Grpc.Server";

package SampleCommandProcessor;

// The service definition.
service CommandProcessor {
  // Unary method
  rpc CommandUnary (CommandRequest) returns (CommandResponse);

  // Server streaming method
  rpc CommandServerStreaming (CommandRequest) returns (stream CommandResponse);

  // Client streaming method
  rpc CommandClientStreaming (stream CommandRequest) returns (CommandResponse);

  // Bi-directional streaming method
  rpc CommandBiDirectionalStreaming (stream CommandRequest) returns (stream CommandResponse);
}

// The request message containing the command's name.
message CommandRequest {
  string name = 1;
}

// The response message containing the message.
message CommandResponse {
  string message =2;
} 
  

Step 3: Set CommandProcessor.proto File Properties

Set Build Action to Protobuf Compiler & gRPC Stub Classes to Server Only.

Step 4: Build the gRPC Server Application to Generate C# Code From the CommandProcessor.proto File

Location of generated C# code: \obj\Debug\net5.0\Protos

Generated C# code contains:

An abstract base type (CommandProcessorBase abstract class) for each service
Classes for any messages (CommandRequset & CommandRequest class)

Step 5: Create a Concrete Implementation of CommandProcessorBase Abstract Class

Add CommandProcessorService.cs class in Services root folder. This service class will inherit from CommandProcessorBase abstract class, will override & provide the implementation for the unimplemented methods of CommandProcessorBase abstract class.

A. Unary method

Return single response after processing of a single request
Call completes when the response is returned
Simple request/response

CommandUnary method:

     C# 
   
 
 
   public override async Task<CommandResponse> CommandUnary(CommandRequest request, ServerCallContext context)
{
  // TODO:: Write your custom "Command Processing Logic" here and return response.
  await Task.Delay(1000);
  return new CommandResponse { Message = $"{request.Name}:: Processed Successfully" };
} 
  

B. Server streaming method

Multiple messages can be streamed back to the caller during the processing of a single request
Call completes when the method returns
Server pushing updates to clients periodically

CommandServerStreaming method:

     C# 
   
 
 
   public override async Task CommandServerStreaming(CommandRequest request, IServerStreamWriter<CommandResponse> responseStream, ServerCallContext context)
{
  // Multi-step request processing & sending out intermediate/partial responses until request is processed completely.
  // TODO:: Write your custom "Command Processing Logic" here and write response to stream.
  await Task.Delay(1000);
  await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Step 1 Completed" });
  await Task.Delay(1000);
  await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Step 2 Completed" });
  await Task.Delay(1000);
  await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Step 3 Completed" });
  await Task.Delay(1000);
  await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Processed Successfully" });
} 
  

C. Client Streaming method

Request stream to the server & single response returned from the server
Call completes when a response message is returned
File upload from client-side

CommandClientStreaming method:

     C# 
   
 
 
   public override async Task<CommandResponse> CommandClientStreaming(IAsyncStreamReader<CommandRequest> requestStream, ServerCallContext context)
{
  var response = new CommandResponse { };

  await foreach (var request in requestStream.ReadAllAsync())
  {
    // Multi request processing & single combined response at the end.
    // TODO:: Write your custom "Command Processing Logic" here and combine responses.
    await Task.Delay(1000);
    var res = new CommandResponse { Message = $"{request.Name}:: Processed Successfully" };
    response.Message += res.Message;
    response.Message += Environment.NewLine;
  }

  return response;
} 
  

Bi-directional streaming method

Client and service can send messages to each other at any time
Call completes when the method returns
Client and server sharing messages like a chat application.

CommandBiDirectionalStreaming method:

 C# 
   
 
 
   public override async Task CommandBiDirectionalStreaming(IAsyncStreamReader<CommandRequest> requestStream, IServerStreamWriter<CommandResponse> responseStream, ServerCallContext context)
{
  await foreach (var request in requestStream.ReadAllAsync())
  {
    // TODO:: Write your custom "Command Processing Logic" here and write response to stream.
    await Task.Delay(1000);
    await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Processed Successfully" });
  }
} 
  

Full Sample code CommandProcessorService.cs service

 C# 
   
 
 
   using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Grpc.Core;
using Microsoft.Extensions.Logging;

namespace SampleApplication.Grpc.Server.Services
{
    public class CommandProcessorService : CommandProcessor.CommandProcessorBase
    {
        private readonly ILogger<CommandProcessorService> logger;

        public CommandProcessorService(ILogger<CommandProcessorService> logger) 
            => this.logger = logger;

        public override async Task<CommandResponse> CommandUnary(CommandRequest request, ServerCallContext context)
        {
            // Simple request & response.
            return await ProcessCommand(request);
        }

        public override async Task CommandServerStreaming(CommandRequest request, IServerStreamWriter<CommandResponse> responseStream, ServerCallContext context)
        {
            // Multi-step request processing & sending out intermediate/partial responses until request is processed completely.
            await ProcessIntermediateSteps(request, responseStream, 1);
            await ProcessIntermediateSteps(request, responseStream, 2);
            await ProcessIntermediateSteps(request, responseStream, 3);
            await ProcessCommand(responseStream, request);
        }

        public override async Task<CommandResponse> CommandClientStreaming(IAsyncStreamReader<CommandRequest> requestStream, ServerCallContext context)
        {
            var response = new CommandResponse { };

            await foreach (var request in requestStream.ReadAllAsync())
            {
                // Multi request processing & single combined response at the end.
                var res = await ProcessCommand(request);
                response.Message += res.Message;
                response.Message += Environment.NewLine;
            }

            return response;
        }

        public override async Task CommandBiDirectionalStreaming(IAsyncStreamReader<CommandRequest> requestStream, IServerStreamWriter<CommandResponse> responseStream, ServerCallContext context)
        {
            await foreach (var request in requestStream.ReadAllAsync())
            {
                await ProcessCommand(responseStream, request);
            }
        }

        private static async Task<CommandResponse> ProcessCommand(CommandRequest request)
        {
            // TODO:: Write your custom "Command Processing Logic" here and return response.
            await Task.Delay(1000);
            return new CommandResponse { Message = $"{request.Name}:: Processed Successfully" };
        }


        private static async Task ProcessIntermediateSteps(CommandRequest request, IServerStreamWriter<CommandResponse> responseStream, int stepCount)
        {
            // TODO:: Write your custom "Command Processing Logic" here and write response to stream.
            await Task.Delay(1000);
            await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Step {stepCount} Completed" });
        }

        private static async Task ProcessCommand(IServerStreamWriter<CommandResponse> responseStream, CommandRequest request)
        {
            // TODO:: Write your custom "Command Processing Logic" here and write response to stream.
            await Task.Delay(1000);
            await responseStream.WriteAsync(new CommandResponse { Message = $"{request.Name}:: Processed Successfully" });
        }
    }
} 
  

Step 6: Add CommandProcessorService Service to the Routing Pipeline With the MapGrpcService Method in the Startup.cs

 C# 
   
   app.UseEndpoints(endpoints =>
{
  endpoints.MapGrpcService<CommandProcessorService>();
});

That's it. gRPC Server Application is ready!

application

Published at DZone with permission of Kapil Khandelwal, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Related

Trending