Actors入门

先决条件

.Net Core SDK 3.0
Dapr CLI
Dapr DotNet SDK

概述

本文档描述如何在客户端应用程序上创建Actor（MyActor）并调用其方法.

MyActor --- MyActor.Interfaces|+- MyActorService|+- MyActorClient

接口项目（\MyActor\MyActor.Interfaces）。此项目包含参与者的接口定义。Actor接口可以在任何名称的项目中定义。接口定义了actor实现和调用actor的客户机共享的actor契约。因为客户机项目可能依赖于它，所以通常在与actor实现分离的程序集中定义它是有意义的.
actor服务项目（\MyActor\MyActor service）。这个项目实现了ASP.Net核心web服务，该服务将承载参与者。它包含actor MyActor.cs的实现。actor实现是从基类型actor派生并实现MyActor.interfaces项目中定义的接口的类。actor类还必须实现一个构造函数，该构造函数接受ActorService实例和ActorId，并将它们传递给基本actor类.
actor客户端项目（\MyActor\MyActor client）此项目包含actor客户端的实现，该客户端调用actor接口中定义的MyActor方法.

第1步 - 创建Actor接口

Actor接口定义Actor实现和调用Actor的客户机共享的Actor契约.

Actor接口定义如下:

Actor接口必须继承 Dapr.Actors.IActor 接口
Actor方法的返回类型必须是Task或Task<object>
Actor方法最多可以有一个参数

创建项目和添加依赖

# Create Actor Interfaces
dotnet new classlib -o MyActor.Interfacescd MyActor.Interfaces# Add Dapr.Actors nuget package
dotnet add package Dapr.Actors

升级项目到 .NET Core 3.0

更新csproj文件中的netcore到 .NET Core 3.0

<Project Sdk="Microsoft.NET.Sdk"><PropertyGroup><TargetFramework>netcoreapp3.0</TargetFramework></PropertyGroup><ItemGroup><PackageReference Include="Dapr.Actors" Version="0.1.0-preview01" /></ItemGroup>
</Project>

实现 IMyActor 接口

定义 IMyActor 接口和 MyData 数据对象.

using Dapr.Actors;
using System.Threading.Tasks;namespace MyActor.Interfaces
{public interface IMyActor : IActor{Task<string> SetDataAsync(MyData data);Task<MyData> GetDataAsync();Task RegisterReminder();Task UnregisterReminder();Task RegisterTimer();Task UnregisterTimer();}public class MyData{public string PropertyA { get; set; }public string PropertyB { get; set; }public override string ToString(){var propAValue = this.PropertyA == null ? "null" : this.PropertyA;var propBValue = this.PropertyB == null ? "null" : this.PropertyB;return $"PropertyA: {propAValue}, PropertyB: {propBValue}";}}
}

第2步 - 创建Actor服务

Dapr使用ASP.NET web服务托管Actor服务. 本节将实现 IMyActor 接口以及注册Actor到Dapr运行时.

创建项目及添加依赖

# Create ASP.Net Web service to host Dapr actor
dotnet new webapi -o MyActorServicecd MyActorService# Add Dapr.Actors nuget package
dotnet add package Dapr.Actors# Add Dapr.Actors.AspNetCore nuget package
dotnet add package Dapr.Actors.AspNetCore# Add Actor Interface reference
dotnet add reference ../MyActor.Interfaces/MyActor.Interfaces.csproj

添加Actor实现

实现IMyActor接口并从Dapr.Actors.Actor类派生。下面的示例还演示了如何使用Actor提醒。对于Actor来说，使用提醒，它必须来源于IRemindable。如果不打算使用提醒功能，可以跳过实现下面代码中显示的IRemindable和提醒特定方法.

using Dapr.Actors;
using Dapr.Actors.Runtime;
using MyActor.Interfaces;
using System;
using System.Threading.Tasks;namespace MyActorService
{internal class MyActor : Actor, IMyActor, IRemindable{/// <summary>/// Initializes a new instance of MyActor/// </summary>/// <param name="actorService">The Dapr.Actors.Runtime.ActorService that will host this actor instance.</param>/// <param name="actorId">The Dapr.Actors.ActorId for this actor instance.</param>public MyActor(ActorService actorService, ActorId actorId): base(actorService, actorId){}/// <summary>/// This method is called whenever an actor is activated./// An actor is activated the first time any of its methods are invoked./// </summary>protected override Task OnActivateAsync(){// Provides opportunity to perform some optional setup.Console.WriteLine($"Activating actor id: {this.Id}");return Task.CompletedTask;}/// <summary>/// This method is called whenever an actor is deactivated after a period of inactivity./// </summary>protected override Task OnDeactivateAsync(){// Provides Opporunity to perform optional cleanup.Console.WriteLine($"Deactivating actor id: {this.Id}");return Task.CompletedTask;}/// <summary>/// Set MyData into actor's private state store/// </summary>/// <param name="data">the user-defined MyData which will be stored into state store as "my_data" state</param>public async Task<string> SetDataAsync(MyData data){// Data is saved to configured state store implicitly after each method execution by Actor's runtime.// Data can also be saved explicitly by calling this.StateManager.SaveStateAsync();// State to be saved must be DataContract serialziable.await this.StateManager.SetStateAsync<MyData>("my_data",  // state namedata);      // data saved for the named state "my_data"return "Success";}/// <summary>/// Get MyData from actor's private state store/// </summary>/// <return>the user-defined MyData which is stored into state store as "my_data" state</return>public Task<MyData> GetDataAsync(){// Gets state from the state store.return this.StateManager.GetStateAsync<MyData>("my_data");}/// <summary>/// Register MyReminder reminder with the actor/// </summary>public async Task RegisterReminder(){await this.RegisterReminderAsync("MyReminder",              // The name of the remindernull,                      // User state passed to IRemindable.ReceiveReminderAsync()TimeSpan.FromSeconds(5),   // Time to delay before invoking the reminder for the first timeTimeSpan.FromSeconds(5));  // Time interval between reminder invocations after the first invocation}/// <summary>/// Unregister MyReminder reminder with the actor/// </summary>public Task UnregisterReminder(){Console.WriteLine("Unregistering MyReminder...");return this.UnregisterReminderAsync("MyReminder");}// <summary>// Implement IRemindeable.ReceiveReminderAsync() which is call back invoked when an actor reminder is triggered.// </summary>public Task ReceiveReminderAsync(string reminderName, byte[] state, TimeSpan dueTime, TimeSpan period){Console.WriteLine("ReceiveReminderAsync is called!");return Task.CompletedTask;}/// <summary>/// Register MyTimer timer with the actor/// </summary>public Task RegisterTimer(){return this.RegisterTimerAsync("MyTimer",                  // The name of the timerthis.OnTimerCallBack,       // Timer callbacknull,                       // User state passed to OnTimerCallback()TimeSpan.FromSeconds(5),    // Time to delay before the async callback is first invokedTimeSpan.FromSeconds(5));   // Time interval between invocations of the async callback}/// <summary>/// Unregister MyTimer timer with the actor/// </summary>public Task UnregisterTimer(){Console.WriteLine("Unregistering MyTimer...");return this.UnregisterTimerAsync("MyTimer");}/// <summary>/// Timer callback once timer is expired/// </summary>private Task OnTimerCallBack(object data){Console.WriteLine("OnTimerCallBack is called!");return Task.CompletedTask;}}
}

使用显式actor类型名

默认情况下，客户端看到的actor的“类型”是从actor实现类的名称派生的。如果需要，可以通过将actor attribute属性附加到actor实现类来指定显式类型名.

[Actor(TypeName = "MyCustomActorTypeName")]
internal class MyActor : Actor, IMyActor
{// ...
}

注册 Actor 到 Dapr 运行时

将 MyActor 注册到 actor runtime并设置本地主机端口(https://localhost:3000) , Dapr runtime可以通过该端口调用actor.

private const int AppChannelHttpPort = 3000;public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>WebHost.CreateDefaultBuilder(args).UseStartup<Startup>().UseActors(actorRuntime =>{// Register MyActor actor typeactorRuntime.RegisterActor<MyActor>();}).UseUrls($"http://localhost:{AppChannelHttpPort}/");

更新Startup.cs

public class Startup{...public void ConfigureServices(IServiceCollection services){services.AddRouting();}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();}else{app.UseHsts();}}}

第3步 - 添加客户端

创建一个简单的控制台应用程序来调用actor服务。Dapr SDK提供Actor代理客户端来调用Actor接口中定义的Actor方法.

创建项目并添加依赖

# Create Actor's Client
dotnet new console -o MyActorClientcd MyActorClient# Add Dapr.Actors nuget package
dotnet add package Dapr.Actors# Add Actor Interface reference
dotnet add reference ../MyActor.Interfaces/MyActor.Interfaces.csproj

使用Actor远程服务调用Actor方法

我们建议使用本地代理到actor实例，因为ActorProxy.Create<IMyActor>（actorID，actorType）返回强类型actor实例来设置远程过程调用.

namespace MyActorClient
{using Dapr.Actors;using Dapr.Actors.Client;using MyActor.Interfaces;using System;using System.Threading.Tasks;...static async Task InvokeActorMethodWithRemotingAsync(){var actorType = "MyActor";      // Registered Actor Type in Actor Servicevar actorID = new ActorId("1");// Create the local proxy by using the same interface that the service implements// By using this proxy, you can call strongly typed methods on the interface using Remoting.var proxy = ActorProxy.Create<IMyActor>(actorID, actorType);var response = await proxy.SetDataAsync(new MyData(){PropertyA = "ValueA",PropertyB = "ValueB",});Console.WriteLine(response);var savedData = await proxy.GetDataAsync();Console.WriteLine(savedData);}...
}

非远程方式调用 Actor 方法

如果Actor方法最多接受一个参数，则可以调用Actor方法而无需远程处理（直接通过http或使用ActorProxy中提供的helper方法）。Actor运行时将从客户端反序列化传入的请求体，并将其用作方法参数来调用Actor方法。当进行非远程处理调用时，Actor方法参数和返回类型被序列化，反序列化为JSON.

ActorProxy.Create(actorID, actorType) 返回 ActorProxy 实例并允许使用原始http客户端调用IMyActor中定义的方法.

namespace MyActorClient
{using Dapr.Actors;using Dapr.Actors.Client;using MyActor.Interfaces;using System;using System.Threading.Tasks;...static async Task InvokeActorMethodWithoutRemotingAsync(){var actorType = "MyActor";var actorID = new ActorId("1");// Create Actor Proxy instance to invoke the methods defined in the interfacevar proxy = ActorProxy.Create(actorID, actorType);// Need to specify the method name and response type explicitlyvar response = await proxy.InvokeAsync<string>("SetMyDataAsync", new MyData(){PropertyA = "ValueA",PropertyB = "ValueB",});Console.WriteLine(response);var savedData = await proxy.InvokeAsync<MyData>("GetMyDataAsync");Console.WriteLine(savedData);}...
}

运行Actor

为了验证及调试 actor 服务及客户端, 我们首先需要通过Dapr CLI运行actor服务.

Run Dapr Runtime via Dapr cli
```
$ dapr run --app-id myapp --app-port 3000 dotnet MyActorService.dll
```
在通过Dapr运行时执行MyActorService之后，确保在端口3000上发现应用程序并成功建立actor连接.

INFO[0000] starting Dapr Runtime -- version  -- commitINFO[0000] log level set to: infoINFO[0000] standalone mode configuredINFO[0000] dapr id: myappINFO[0000] loaded component statestore (state.redis)INFO[0000] application protocol: http. waiting on port 3000INFO[0000] application discovered on port 3000INFO[0000] application configuration loaded2019/08/27 14:42:06 redis: connecting to localhost:63792019/08/27 14:42:06 redis: connected to localhost:6379 (localAddr: [::1]:53155, remAddr: [::1]:6379)INFO[0000] actor runtime started. actor idle timeout: 1h0m0s. actor scan interval: 30sINFO[0000] actors: starting connection attempt to placement service at localhost:50005INFO[0000] http server is running on port 3500INFO[0000] gRPC server is running on port 50001INFO[0000] dapr initialized. Status: Running. Init Elapsed 19.699438msINFO[0000] actors: established connection to placement service at localhost:50005INFO[0000] actors: placement order received: lockINFO[0000] actors: placement order received: updateINFO[0000] actors: placement tables updatedINFO[0000] actors: placement order received: unlock...

运行 MyActorClient
如果MyActorClient成功调用托管在MyActorService中的actor，它将在控制台输出.
如果指定不同的Dapr运行时http端口（默认端口：3500），则需要在运行客户端之前设置Dapr_http_port环境变量.
```
Success
PropertyA: ValueA, PropertyB: ValueB
```

原文参考翻译：https://github.com/dapr/dotnet-sdk/blob/master/docs/get-started-dapr-actor.md