识别 Akka HttpRequest 和 HttpResponse？

Question

在使用 Akka HttpRequest 并将请求通过管道传递给参与者时，我无法识别响应。参与者将处理每条将收到的消息，但它不知道哪个请求用于获取此响应。有什么方法可以识别每个请求以匹配响应？

注意：我没有服务器可以再次重新发送请求正文的任何部分。

提前致谢

MySelf.scala

import akka.actor.{ Actor, ActorLogging }
import akka.http.scaladsl.Http
import akka.http.scaladsl.model._
import akka.stream.{ ActorMaterializer, ActorMaterializerSettings }
import akka.util.ByteString

class Myself extends Actor with ActorLogging {

import akka.pattern.pipe
import context.dispatcher

final implicit val materializer: ActorMaterializer = 
       ActorMaterializer(ActorMaterializerSettings(context.system))

def receive = {
  case HttpResponse(StatusCodes.OK, headers, entity, _) =>
    entity.dataBytes.runFold(ByteString(""))(_ ++ _).foreach { body =>
      log.info("Got response, body: " + body.utf8String)
  }
  case resp @ HttpResponse(code, _, _, _) =>
    log.info("Request failed, response code: " + code)
    resp.discardEntityBytes()
  }

}

Main.scala

import akka.actor.{ActorSystem, Props}
import akka.http.scaladsl.Http
import akka.http.scaladsl.model._
import akka.stream.ActorMaterializer

object HttpServerMain extends App {

import akka.pattern.pipe

//  import system.dispatcher
implicit val system = ActorSystem()
implicit val materializer = ActorMaterializer()
// needed for the future flatMap/onComplete in the end
implicit val executionContext = system.dispatcher

val http = Http(system)

val myActor = system.actorOf(Props[MySelf])

http.singleRequest(HttpRequest(uri = "http://akka.io"))
    .pipeTo(myActor)

http.singleRequest(HttpRequest(uri = "http://akka.io/another-request"))
    .pipeTo(myActor)
Thread.sleep(2000)
system.terminate()

Answer 1

您可以简单地使用 map 来转换 Future 并在将其通过管道传输到 myActor 之前向其添加某种 ID（为此通常称为相关 ID）：

http.singleRequest(HttpRequest(uri = "http://akka.io"))
    .map(x => (1, x)).pipeTo(myActor)

您需要更改模式匹配块以获取元组：

case (id, HttpResponse(StatusCodes.OK, headers, entity, _)) =>

如果您不能t/don出于某种原因不想更改您的模式匹配块，您可以使用相同的方法，而是将唯一的 HTTP header 添加到您完成的请求中（使用 copy) 用这样的东西（如果编译不检查）：

// make a unique header name that you are sure will not be
// received from http response:
val correlationHeader: HttpHeader = ... // mycustomheader

// Basically hack the response to add your header:
http.singleRequest(HttpRequest(uri = "http://akka.io"))
    .map(x => x.copy(headers = correlationHeader +: headers)).pipeTo(myActor)

// Now you can check your header to see which response that was:
case HttpResponse(StatusCodes.OK, headers, entity, _) =>
  headers.find(_.is("mycustomheader")).map(_.value).getOrElse("NA")

与之前的选项相比，这更像是一种黑客攻击，因为您正在修改响应。

Answer 2

我认为你不能直接使用 pipeTo 来做到这一点，因为它本质上只是 andThen 调用你的 Future。一种选择是 map 然后发送一个 (request, response) 元组给演员：

val request = HttpRequest(uri = "http://akka.io")
http.singleRequest(request).map {
  response => myActor ! (request, response)
}

class Myself extends Actor with ActorLogging {
  ...
  def receive = {
    case (request, HttpResponse(StatusCodes.OK, headers, entity, _)) =>
      ...

    case (request, resp @ HttpResponse(code, _, _, _)) =>
      log.info(request.toString)
      ...
  }
}

识别 Akka HttpRequest 和 HttpResponse？

Identify Akka HttpRequest and HttpResponse?

scala

http

akka

akka-http

MySelf.scala

Main.scala