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+====== Scala distributed ping pong ======
+This small scala example demonstrates the simplicity in which distributed programming is possible using the actor model.  We setup an ECHOSERVER that simply responds with a PONG to any PING request it receives and we run this on an arbitrary server.
+<code scala>
+/*
+ * EchoServer.scala
+ */
+package echoapp
+import scala.actors.Actor._
+import scala.actors.remote.{Locator,Node,RemoteActor}
+import scala.actors.remote.RemoteActor.{alive,register}
+class Server(me : Locator) {
+    RemoteActor.classLoader = getClass().getClassLoader()
+    actor {
+        alive(me.node.port)
+        register(me.name, self)
+        loop {
+            react {
+                case 'PING => reply("PONG") // equiv:  sender ! "PONG"
+                case msg => println(msg)
+            }
+        }
+    }
+}
+object EchoServer  {
+    def main(args: Array[String]) {
+        val me = new Locator(Node("127.0.0.1", 9010), 'echoServer)
+        new Server(me)
+        println("Echo server started")
+    }
+}
+</code>
+For the sake of brevity the IP address of where the ECHOSERVER is running has been hardcoded.  The client sends a PING message to the remote echo server and gathers the response(s).
+<code scala>
+/*
+ * EchoClient.scala
+ */
+package echoapp
+import scala.actors.Actor._
+import scala.actors.remote.{Locator,Node,RemoteActor}
+import scala.actors.remote.RemoteActor._
+class Client(servloc : Locator) {
+    RemoteActor.classLoader = getClass().getClassLoader()
+    val server = select(servloc.node, servloc.name)
+    actor {
+        // The response is sent back to the thread that did the send.
+        // If we move to this to main() then this is where the reponse will go
+        // as we have no react/receive there it will be lost.
+        server ! 'PING
+        loop {
+            react {
+                case msg =>
+                    println(msg)
+            }
+        }
+    }
+}
+object EchoClient {
+    def main(args: Array[String]) {
+        val echoServer = Locator(Node("192.168.1.13", 9010), 'echoServer)
+        new Client(echoServer)
+    }
+}
+</code>
+{{tag>scala programming}}