!act #15626 expose DatagramChannel creation in DatagramChannelCreator

* move channel creation logic to a separate trait
* new Java API: AbstractSocketOption

akka-samples/akka-docs-udp-multicast/src/main/scala/ScalaUdpMulticast.scala

@@ -0,0 +1,59 @@
+/**
+ * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+
+package docs.io
+
+import java.net.{InetAddress, InetSocketAddress, NetworkInterface, StandardProtocolFamily}
+import java.nio.channels.DatagramChannel
+
+import akka.actor.{Actor, ActorLogging, ActorRef}
+import akka.io.Inet.{DatagramChannelCreator, SocketOption}
+import akka.io.{IO, Udp}
+import akka.util.ByteString
+
+//#inet6-protocol-family
+final case class Inet6ProtocolFamily() extends DatagramChannelCreator {
+  override def create() =
+    DatagramChannel.open(StandardProtocolFamily.INET6)
+}
+//#inet6-protocol-family
+
+//#multicast-group
+final case class MulticastGroup(address: String, interface: String) extends SocketOption {
+  override def afterConnect(c: DatagramChannel) {
+    val group = InetAddress.getByName(address)
+    val networkInterface = NetworkInterface.getByName(interface)
+    c.join(group, networkInterface)
+  }
+}
+//#multicast-group
+
+class Listener(iface: String, group: String, port: Int, sink: ActorRef) extends Actor with ActorLogging {
+  //#bind
+  import context.system
+  val opts = List(Inet6ProtocolFamily(), MulticastGroup(group, iface))
+  IO(Udp) ! Udp.Bind(self, new InetSocketAddress(port), opts)
+  //#bind
+
+  def receive = {
+    case Udp.Bound(to) => log.info(s"Bound to $to")
+    case Udp.Received(data, remote) =>
+      val msg = data.decodeString("utf-8")
+      log.info(s"Received '$msg' from '$remote'")
+      sink ! msg
+  }
+}
+
+class Sender(group: String, port: Int, msg: String) extends Actor with ActorLogging {
+  import context.system
+  IO(Udp) ! Udp.SimpleSender(List(Inet6ProtocolFamily()))
+
+  def receive = {
+    case Udp.SimpleSenderReady => {
+      val remote = new InetSocketAddress(group, port)
+      log.info(s"Sending message to $remote")
+      sender() ! Udp.Send(ByteString(msg), remote)
+    }
+  }
+}