我正在学习akka-remote,我在LocalActorSystem中做的一件事是获取远程actor参考并向他发送消息
class LocalActor extends Actor {
val remote = context.actorSelection("akka.tcp://HelloRemoteSystem@127.0.0.1:5150/user/RemoteActor")
var counter = 0
def receive = {
case "START" =>
remote ! "Hello from the LocalActor"
case msg: String =>
println(s"LocalActor received message: '$msg'")
if (counter < 5) {
sender ! "Hello back to you"
counter += 1
}
}
}
我的遥控器看起来像
object Remote extends App {
val system = ActorSystem("HelloRemoteSystem",ConfigFactory.load("remote"))
val remoteActor = system.actorOf(Props[RemoteActor],name = "RemoteActor")
remoteActor ! "The RemoteActor is alive"
}
class RemoteActor extends Actor {
def receive = {
case msg: String =>
println(s"RemoteActor received message '$msg'")
sender ! "Hello from the RemoteActor"
}
}
我还想看一下remoteActor,这样如果死了,LocalActorSystem就知道了.所以我做了
val remote = context.actorSelection("akka.tcp://HelloRemoteSystem@127.0.0.1:5150/user/RemoteActor")
context watch remote
但随后编译器失败并显示以下消息
题
>为什么我能够向ActorSelection发送消息,因为它不是Actor？
>我如何观看RemoteActor？
更新
但是,弃用的API不会抱怨
val remote = context.actorFor("akka.tcp://HelloRemoteSystem@127.0.0.1:5150/user/RemoteActor")
context watch remote
解决方法
当您通过actorSelection进行查找时,您获得的那种类型的对象是ActorSelection而不是ActorRef.现在,ActorSelection确实支持tell(！)和ask(？),因此您可以像使用ActorRef一样与它进行交互.但是通过actorSelection查找的actor支持通配符的概念,因此您返回的ActorSelection可能代表多个actor,并允许您向多个actor发送消息.例如,如果您这样做：
system.actorSelection( “/用户/富/ *”)
这将为您绑定到名称foo的父ActorRef下的所有子项提供ActorSelection.如果有两个孩子并且您通过该ActorSelection发送消息,则该消息将被传递给两个孩子.
在您的情况下,看起来您正在查找单个actor实例.在这种情况下,您可以通过调用resolveOne从ActorSelection获取ActorRef.这将返回Future [ActorRef],完成后将为您提供可以远程观看的ActorRef.您还可以向ActorSelection发送Identify消息,并等待包含要观看的ref的ActorIdentity响应.
您应该查看文档here,特别是通过Actor Selection选择识别演员.
