implement remote routers

- split out actual routing functionality into *Like traits to be
  reusable
- make RemoteRouterConfig which only differs in how remote placement is
  initiated
- teach RemoteDeployer how to convert local RouterConfig in case config
  key “target.nodes” is set
- IT WORKS! All tests GREEN
- oh, yeah, had to make ActorPath serializable ...

akka-remote/src/test/scala/akka/remote/RemoteRouterSpec.scala

@@ -0,0 +1,58 @@
+/**
+ * Copyright (C) 2009-2011 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.remote
+
+import akka.testkit._
+import akka.routing._
+import akka.actor._
+import com.typesafe.config._
+
+object RemoteRouterSpec {
+  class Echo extends Actor {
+    def receive = {
+      case _ ⇒ sender ! self.path
+    }
+  }
+}
+
+class RemoteRouterSpec extends AkkaSpec("""
+akka {
+  actor.provider = "akka.remote.RemoteActorRefProvider"
+  cluster.nodename = Nonsense
+  remote.server {
+    hostname = localhost
+    port = 12345
+  }
+  actor.deployment {
+    /blub {
+      router = "round-robin"
+      nr-of-instances = 2
+      target.nodes = ["akka://remote_sys@localhost:12346"]
+    }
+  }
+}
+""") with ImplicitSender {
+
+  import RemoteRouterSpec._
+
+  val conf = ConfigFactory.parseString("akka.remote.server.port=12346").withFallback(system.settings.config)
+  val other = ActorSystem("remote_sys", conf)
+
+  override def atTermination() {
+    other.stop()
+  }
+
+  "A Remote Router" must {
+
+    "deploy its children on remote host driven by configuration" in {
+      val router = system.actorOf(Props[Echo].withRouting(RoundRobinRouter(2)), "blub")
+      router ! ""
+      expectMsgType[ActorPath].toString must be === "akka://remote_sys@localhost:12346/remote/RemoteRouterSpec@localhost:12345/user/blub/c1"
+      router ! ""
+      expectMsgType[ActorPath].toString must be === "akka://remote_sys@localhost:12346/remote/RemoteRouterSpec@localhost:12345/user/blub/c2"
+    }
+
+  }
+
+}