Akka HTTP“每个请求的参与者"图案 [英] Akka HTTP "actor per request" pattern

问题描述

目前我正在尝试实施 "actor-per-request" 模式由 NET-A-PORTER devs 在 Akka HTTP 中提出.我面临的问题是文档中的任何地方都没有记录这种模式.似乎没有办法做到以下几点:

Currently I'm trying to implement the "actor-per-request" pattern proposed by NET-A-PORTER devs in Akka HTTP. The problem I'm facing is that this pattern is not documented anywhere in the docs. There doesn't seem to be a way to do the following:

IO(Http) ! Http.Bind(serviceActor, "localhost", port = 38080)

如何在不使用 Spray 的情况下为每个请求使用一个 Akka actor?

How can I use one Akka actor per request without using Spray?

推荐答案

HttpExt 类有一个方法 bindAndHANdleAsync 可用于此目的.此方法接受具有以下签名的函数:

The HttpExt class has a method bindAndHAndleAsync that can be used for this purpose. This method takes in a function with the following signature:

handler: (HttpRequest) ⇒ Future[HttpResponse]

所以，假设我们有一个 Actor，当被问及 HttpRequest 时，它会产生一个 HttpResponse:

So, suppose we have an Actor that will produce an HttpResponse when asked about an HttpRequest:

class HttpResponseHandlerActor extends Actor {
  override def receive = {
    case _ : HttpRequest => 
      sender() ! HttpResponse(200, entity = "Response From Actor")
  }
}

低效回答

您的问题明确询问如何为每个请求使用 1 个 Actor，为此我们现在可以使用我们的 Actor 类来创建处理函数:

Your question explicitly asks how to use 1 Actor per request, to do that we can now use our Actor class to create a handler function:

implicit val actorSystem = ActorSystem()

implicit val timeout = Timeout(5 seconds)

val handler : (HttpRequest) => Future[HttpResponse] = (httpRequest) = {
  val actorHandlerRef = 
    system.actorOf(Props[HttpResponseHandlerActor], "responseActor")

  (actorHandlerRef ask httpRequest).mapTo[HttpResponse]
}

我们现在可以使用这个函数来绑定我们的服务器:

We can now use this function to bind our server with:

val serverBinding : Future[ServerBinding] = 
  Http().bindAndHandleAsync(handler, "localhost", 8080)

高效回答

通常没有必要为每个请求重新创建一个新的 Actor，通常您希望创建 1 个 Actor 并为每个请求使用它.
因此，我们可以将 Actor 创建移到 handler 之外:

It is usually not necessary to re-create a new Actor for each request, typically you want to create 1 Actor and use it for every request.
Therefore we can move the Actor creation outside of handler:

val handler : (ActorRef) => (HttpRequest) => Future[HttpResponse] = 
  (actorRef) => (httpRequest) =>
     (actorRef ask httpRequest).mapTo[HttpResponse]

服务器绑定现在稍微修改为:

The server binding is now slightly modified to:

val singleResponseActorRef = 
  system.actorOf(Props[HttpResponseHandlerActor], "responseActor")

val serverBinding : Future[ServerBinding] = 
  Http().bindAndHandleAsync(handler(singleResponseActorRef),
                            "localhost", 
                            8080)

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