Orleans的Grain實作專案可以使用.NET Core/.NET5的依賴注入(Dependency Injection, DI)機制，這樣可以讓Grain實作專案更容易測試，也可以藉此存取到框架核心的功能，Grain State的功能就需要使用依賴注入。
以下示範如何使用依賴注入做到：
建立新的示範Grain專案：在昨天進度的原始碼git專案，分別建立新的RPC介面專案和Grain實作專案：
| | 路徑 | 專案名稱 | 專案類型 |
|:---------- | :-------- | --------|
| src/Shared | RpcDemo.Interfaces.ASCIIArt | .NET 6 類別庫(class library) |
| src/Grains | RpcDemo.Grains.Cowsay | .NET 6 類別庫(class library) |
建議將這兩個專案各自加入根目錄的Orleans.sln方案的 Shared以及Grains方案資料夾(Solution Folder)中。
安裝對應的Nuget套件：
| | 專案名稱 | 需安裝Nuget套件 |
| :---------- | :-------- |
| RpcDemo.Interfaces.ASCIIArt | Microsoft.Orleans.Core.Abstractions 、 Microsoft.Orleans.CodeGenerator.MSBuild |
| RpcDemo.Grains.Cowsay | Cowsay.Abstractions 、 Microsoft.Extensions.Logging.Abstractions 、 Microsoft.Orleans.Core 、 Microsoft.Orleans.CodeGenerator.MSBuild |
| RpcDemo.Hosting.Console | Cowsay.Extensions.DependencyInjection 、 Microsoft.Extensions.DependencyInjection.Abstractions |
將 RpcDemo.Interfaces.ASCIIArt 專案加入至 RpcDemo.Grains.Cowsay 和 RpcDemo.Client.Console 的專案對專案參考(project-to-project reference)中。
將 RpcDemo.Grains.Cowsay 專案加入至 src\Hosting\Server 的 RpcDemo.Hosting.Console 這個Silo服務專案的專案對專案參考(project-to-project reference)中。
在 RpcDemo.Interfaces.ASCIIArt 專案中，Class1.cs 檔案移除，使用以下內容建立一個新的C#介面檔 ICowsayGrain.cs ：
namespace RpcDemo.Interfaces.ASCIIArt
{
public interface ICowsayGrain : IGrainWithStringKey
{
Task<string> Say(string message);
}
}
在 RpcDemo.Grains.Cowsay 專案中，Class1.cs 檔案移除，使用以下內容建立一個新的C#檔 CowsayGrain.cs ：
using Cowsay.Abstractions;
using Microsoft.Extensions.Logging;
using Orleans;
using RpcDemo.Interfaces.ASCIIArt;
namespace RpcDemo.Grains.Cowsay;
public class CowsayGrain : Grain, ICowsayGrain
{
private readonly ICattleFarmer _cattleFarmer;
private string? _grainId;
private readonly ILogger<CowsayGrain> _logger;
public CowsayGrain(ICattleFarmer cattleFarmer, ILogger<CowsayGrain> logger)
{
_cattleFarmer = cattleFarmer;
_logger = logger;
}
public override Task OnActivateAsync()
{
_grainId = this.GetPrimaryKeyString();
return base.OnActivateAsync();
}
//Demo using injected service
public async Task<string> Say(string message)
{
var cattle = await _cattleFarmer.RearCowAsync(_grainId ?? "default");
var saying = cattle.Say(message);
_logger.LogInformation("Cow {0} said:\r\n{1}", _grainId, saying);
return saying;
}
}
修改RpcDemo.Hosting.Console Silo專案的 Program.cs 檔案為以下內容：
using System.Net;
using System.Reflection;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Orleans;
using Orleans.Configuration;
using Orleans.Hosting;
using RpcDemo.Grains.Cowsay;
using RpcDemo.Grains.Greeting;
var siloHost = new SiloHostBuilder()
.ConfigureServices(services => { services.AddCowsay(); })
.UseLocalhostClustering()
.Configure<ClusterOptions>(options =>
{
options.ClusterId = "console-host-01";
options.ServiceId = "Demo Greeting Service";
})
.Configure<EndpointOptions>(options => options.AdvertisedIPAddress = IPAddress.Loopback)
.ConfigureApplicationParts(parts =>
{
parts.AddApplicationPart(typeof(HelloGrain).Assembly).WithReferences();
parts.AddApplicationPart(typeof(CowsayGrain).Assembly).WithReferences();
})
.ConfigureLogging(logging =>
{
logging.AddConsole();
logging.AddDebug();
})
.Build();
//Tricks to manually wait for Ctrl+C key press
var waitForProcessShutdown = new ManualResetEvent(false);
Console.CancelKeyPress += (sender, eventArgs) =>
{
eventArgs.Cancel = true;
waitForProcessShutdown.Set();
};
await siloHost.StartAsync();
Console.WriteLine("===\r\nOrleans Silo started and able to connect,\r\nPress Ctrl+C to shut down when client finish demonstration...\r\n===");
waitForProcessShutdown.WaitOne();
Console.WriteLine("Shutting down Silo...");
await siloHost.StopAsync().ConfigureAwait(false);
Console.WriteLine("===\r\nSilo shutdown complete, exiting...\r\n===");
Environment.Exit(0);
最主要的差異如下圖：
第12行增加了 ConfigureServices() 方法的呼叫以便註冊依賴注入的元件，還有第22行將 CowsayGrain 加入Silo要載入的Grain類別之設定 。
修改RpcDemo.Client.Console Client專案的 Program.cs 檔案為以下內容：
using Orleans;
using Orleans.Configuration;
using RpcDemo.Interfaces.ASCIIArt;
using RpcDemo.Interfaces.Hello;
using static System.Console;
WriteLine("\r\n---Orleans RPCDemo Client---");
WriteLine("\r\n---\r\nInitializing Orleans Client...\r\n---");
var client = new ClientBuilder()
.UseLocalhostClustering()
.Configure<ClusterOptions>(options =>
{
options.ClusterId = "console-client-01";
options.ServiceId = "Demo Greeting Service";
})
.ConfigureApplicationParts(parts =>
{
parts.AddApplicationPart(typeof(IHelloGrain).Assembly).WithReferences();
parts.AddApplicationPart(typeof(ICowsayGrain).Assembly).WithReferences();
})
.Build();
WriteLine(
"Please wait until Orleans Server is started and ready for connections, then press any key to start connect...");
ReadKey();
await client.Connect();
WriteLine("\r\n---\r\nOrleans Client connected\r\n---");
var helloGrain = client.GetGrain<IHelloGrain>(0);
var helloResult = await helloGrain.SayHello("Orleans");
WriteLine($"\r\n---\r\nCall HelloGrain.SayHello(\"Orleans\") =\r\n{helloResult}\r\n---");
var cowsayGrain = client.GetGrain<ICowsayGrain>("default");
var cowsayResult = await cowsayGrain.Say("Orleans");
WriteLine($"\r\n---\r\nCall CowsayGrain.Say(\"Orleans\") =\r\n{cowsayResult}\r\n---");
WriteLine("Demonstration finished, press any key to exit...");
ReadKey();
await client.Close();
client.Dispose();
在客戶端的程式碼也是類似Silo相對應的加了對 ICowsayGrain RPC介面的註冊，後續就是取得RPC參考實體和呼叫 Say() 方法，並且輸出結果。
實際執行起來的 Demo 畫面如下，可以看到CowsayGrain藉由DI注入的Logger可以把訊息w寫到Silo的Debug Console的Log訊息上：
在程式碼專案根目錄的 tests 目錄之下建立一個 CowsayGrain.Tests 的xUnit單元測試專案：
dotnet new xunit --no-restore --name CowsayGrain.Tests
將 Microsoft.Orleans.TestingHost 、 ILogger.Moq 、 Moq 這幾個Nuget套件安裝到測試專案中。
將 RpcDemo.Grains.Cowsay 專案加入至此測試專案的專案對專案參考(project-to-project reference)中。
將 CowsayGrain.Tests 測試專案的預設 UnitTest1.cs 檔刪除，新增 CowsayGrainTest.cs 檔案為以下內容：
using Cowsay.Abstractions;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Moq;
using Orleans.Hosting;
using Orleans.TestingHost;
using RpcDemo.Interfaces.ASCIIArt;
using SUT = RpcDemo.Grains.Cowsay;
namespace CowsayGrain.Tests;
public class CowsayGrainTest
{
private static Mock<ILogger<SUT.CowsayGrain>>? _mockLogger;
private class TestSiloConfigurator : ISiloConfigurator
{
public void Configure(ISiloBuilder siloBuilder)
{
_mockLogger = new Mock<ILogger<SUT.CowsayGrain>>();
var mockLoggerFactory = new Mock<ILoggerFactory>();
mockLoggerFactory
.Setup(x => x.CreateLogger(It.IsAny<string>()))
.Returns(() => _mockLogger.Object);
var mockCow = new Mock<ICow>();
mockCow
.Setup(x => x.Say(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>(), It.IsAny<int>(),
It.IsAny<bool>()))
.Returns((string message, string eyes, string tongue, int cols, bool isThought) => message);
var mockCattleFarmer = new Mock<ICattleFarmer>();
mockCattleFarmer.Setup(x => x.RearCowAsync(It.IsAny<string>())).ReturnsAsync(mockCow.Object);
siloBuilder
.ConfigureServices(services =>
{
services.AddSingleton(mockCattleFarmer.Object);
services.AddSingleton(mockLoggerFactory.Object);
});
}
}
[Fact]
public async Task SayTest()
{
//Arrange
var builder = new TestClusterBuilder();
builder.AddSiloBuilderConfigurator<TestSiloConfigurator>();
var cluster = builder.Build();
await cluster.DeployAsync();
const string expected = "Hello Orleans!";
//Act
var grain = cluster.GrainFactory.GetGrain<ICowsayGrain>("default");
var result = await grain.Say(expected);
//Assert
Assert.Equal(expected, result);
_mockLogger!.VerifyLog(logger =>
logger.LogInformation("Cow {0} said:\r\n{1}", It.IsAny<string>(), It.IsAny<string>()), Times.Exactly(1));
}
}
ILogger.Mq可換掉實際被依賴注入的Logger實體以便在測試專案內檢驗Grain實作程式碼時是否有呼叫到寫Log的功能，如 LogInformation()；而使用Moq來換掉原本Cowsay函式庫的依賴注入介面： ICattleFarmer 的 RearCowAsync() 方法和 ICow物件實體呼叫 Say() 方法提供的的結果，以便在測試專案內換掉原本Cowsay函式庫會印出ASCII圖案的行為，直接回傳原本輸入的訊息，方便做Assert驗證。
而原本Cowsay函式庫提供用來簡化依賴注入註冊樣版程式碼的service.AddCowSay()擴充方法，其內部的實作就是將ICattleFarmer以Singleton生命週期註冊到DI容器中；因此在測試Silo的配置設定程式碼，只需也做同樣的方式註冊預備好的mock物件，就可以在跑測試時換掉原本的依賴注入實體來使用，同樣的技巧也可以換掉 Orleans 一些提供公開介面(Interface)的框架層級物件，以方便測試。
整個完成的範例程式GitHub專案在：https://github.com/windperson/OrleansRpcDemo/tree/day09
明天將繼續介紹Orleans最特殊的Grain State狀態儲存功能，敬請期待。
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