ASP.NET Core gRPC

首先要下载 Visual Studio 预览版 和 .NET Core 3.0v SDK。

如果不想安装 VS 预览版，可以参考 .NET Core tooling update for Visual Studio 2017 version 15.9 启用预览版的 .NET Core SDK。（选项位置：Tools > Options > Projects and Solutions > .NET Core: > Use Previews of the .NET Core SDK）

具体的教程参考下面的官方文档：

1. 教程：开始使用 ASP.NET Core 中的 gRPC 服务

   简单来说就是创建一个 ASP.NET Core Web Application => gRPC 服务 模板项目。
   直接使用该默认项目即可。其代码如下：

   依赖项：

   • Google.Protobuf -Version 3.7.0
   • Grpc.AspNetCore.Server -Version 0.1.20-pre1
   • Grpc.Tools -Version 1.20.0-pre3

   Program.cs

   using System;
   using System.Collections.Generic;
   using System.IO;
   using System.Linq;
   using System.Threading.Tasks;
   using Microsoft.AspNetCore.Hosting;
   using Microsoft.Extensions.Hosting;
   
   namespace FirstGrpc
   {
       public class Program
       {
           public static void Main(string[] args)
           {
               CreateHostBuilder(args).Build().Run();
           }
   
           public static IHostBuilder CreateHostBuilder(string[] args) =>
               Host.CreateDefaultBuilder(args)
                   .ConfigureWebHostDefaults(webBuilder =>
                   {
                       webBuilder.UseStartup<Startup>();
                   });
       }
   }

   Startup.cs

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Threading.Tasks;
   using Microsoft.AspNetCore.Builder;
   using Microsoft.AspNetCore.Hosting;
   using Microsoft.Extensions.DependencyInjection;
   using Microsoft.Extensions.Hosting;
   
   namespace FirstGrpc
   {
       public class Startup
       {
           // This method gets called by the runtime. Use this method to add services to the container.
           // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
           public void ConfigureServices(IServiceCollection services)
           {
               services.AddGrpc();
           }
   
           // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
           public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
           {
               if (env.IsDevelopment())
               {
                   app.UseDeveloperExceptionPage();
               }
   
               app.UseRouting();
   
               app.UseEndpoints(endpoints =>
               {
                   // Communication with gRPC endpoints must be made through a gRPC client.
                   // To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909
                   endpoints.MapGrpcService<GreeterService>();
               });
           }
       }
   }

   Protos/greet.proto

   syntax = "proto3";
   
   package Greet;
   
   // The greeting service definition.
   service Greeter {
   // Sends a greeting
   rpc SayHello (HelloRequest) returns (HelloReply) {}
   }
   
   // The request message containing the user's name.
   message HelloRequest {
   string name = 1;
   }
   
   // The response message containing the greetings.
   message HelloReply {
   string message = 1;
   }

   Services/GreeterService.cs

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Threading.Tasks;
   using Greet;
   using Grpc.Core;
   
   namespace FirstGrpc
   {
       public class GreeterService : Greeter.GreeterBase
       {
           public override Task<HelloReply> SayHello(HelloRequest request, ServerCallContext context)
           {
               return Task.FromResult(new HelloReply
               {
                   Message = "Hello " + request.Name
               });
           }
       }
   }

   appsettings.json

   {
       "Logging": {
           "LogLevel": {
           "Default": "Warning",
           "Microsoft.Hosting.Lifetime": "Information"
           }
       },
       "AllowedHosts": "*",
       "Kestrel": {
           "EndpointDefaults": {
           "Protocols": "Http2"
           }
       }
   }

2. 教程：创建 .NET Core gRPC 客户端

   暂时还么有 gRPC 客户端的模板，需要创建 控制台项目，然后手动添加 NuGet 包。

   Install-Package Grpc.Core
   Install-Package Google.Protobuf
   Install-Package Grpc.Tools

   复制 Protos\greet.proto 到客户端项目后，需手动修改工程文件。

   右键点击工程，选择 编辑项目文件 选项。

   在 Project 下新增一个 ItemGroup。

   <ItemGroup>
       <Protobuf Include="Protos\greet.proto" GrpcServices="Client" />
   </ItemGroup>

   保存后重新加载项目。

   修改 Program.cs 中的 main 方法。

   using Greet;
   using Grpc.Core;
   using System;
   using System.Threading.Tasks;
   
   namespace FirstGrpcClient
   {
       class Program
       {
           static async Task Main(string[] args)
           {
               // The port number here must match the port of the gRPC server
               var channel = new Channel("localhost:50051", ChannelCredentials.Insecure);
               var client = new Greeter.GreeterClient(channel);
   
               var reply = await client.SayHelloAsync(new HelloRequest { Name = "GreeterClient" });
               Console.WriteLine("Greeting: " + reply.Message);
   
               await channel.ShutdownAsync();
   
               Console.WriteLine("Press any key to exit...");
               Console.ReadKey();
           }
       }
   }

   分别启动两个项目后，客户端程序打印结果如下：

   Greeting: Hello GreeterClient
   Press any key to exit...

3. 官方的 示例代码

4. 项目结构