UDP Listener

[Alex Boga]

Hi Trustin,

Thanks for the reply, below is the example that works, it's from internet,
and mean-while I found out what it didn't like:

If instead:
DatagramChannel datagramChannel = (DatagramChannel) bootstrap.bind(new
InetSocketAddress(localIpAddress, multicastPort));

I do something like:
DatagramChannel datagramChannel = (DatagramChannel) bootstrap.bind(new
InetSocketAddress(multicastPort));

It works.

I assume that it prefers binding to (lo) instead (eth0), I don't know if
it's because of netty or due to system configuration.

Best regards,
Alex.

-------------------------------------------------------------------------------------------------------------------
import java.net.*;  /* import networking package */
import java.io.*;   /* import input/output package */

public class mcreceive {
public static final int MAX_LEN  = 1024;  /* max receive buffer */
public static final int MIN_PORT = 1024;  /* min network port */
public static final int MAX_PORT = 65535; /* max network port */

public static void main(String argv[]) {
        InetAddress mcAddress=null; /* multicast address */
        int mcPort=0;               /* multicast port */
        int ttl=1;                  /* time to live */
        boolean done=false;         /* variable for send loop */

        /* validate number of arguments */
        if (argv.length != 2) {
                System.out.println("Usage: mcreceive " +
                         "<Multicast IP> <Multicast Port>");
                System.exit(1);
         }

        /* validate the multicast address argument */
        try {
                mcAddress = InetAddress.getByName(argv[0]);    }
                catch (UnknownHostException e) {
                System.err.println(argv[0] + " is not a valid IP address");
                System.exit(1);
         }

        /* validate address argument is a multicast IP */
        if (! mcAddress.isMulticastAddress()) {
                System.err.println(mcAddress.getHostAddress() +
                         " is not a multicast IP address.");
                System.exit(1);
        }

        /* parse and validate port argument */
        try {
                mcPort = Integer.parseInt(argv[1]);
        }       catch (NumberFormatException nfe) {
                System.out.println("Invalid port number " + argv[1]);
                System.exit(1);
        }

        if ((mcPort < MIN_PORT) || (mcPort > MAX_PORT)) {
                System.out.println("Invalid port number " + mcPort);
                System.out.println("Port should be in range " + MIN_PORT
                         + " to " + MAX_PORT);
                System.exit(1);
        }

        try {

                /* instantiate a MulticastSocket */
                MulticastSocket sock = new MulticastSocket(mcPort);

                /* set the address reuse option */
                sock.setReuseAddress(true); // Java 1.4 and higher

                /* join the multicast group */
                sock.joinGroup(mcAddress);

                while (!done) {  /* loop forever */

                        /* create a new DatagramPacket with an empty buffer
*/
                        byte[] buf = new byte[MAX_LEN];
                        DatagramPacket packet = new DatagramPacket(buf,
buf.length);

                        /* wait to receive packet into the DatagramPacket
instance */
                        sock.receive(packet);

                        /* output the data from the packet received */
                        System.out.println("Received " + packet.getLength()
+
                                " bytes from " + packet.getAddress() + ": "
                                + new
String(packet.getData(),0,packet.getLength()));
                }

                sock.leaveGroup(mcAddress);
                sock.close();
        }       catch (IOException e) {
                System.err.println(e.toString());
                System.exit(1);
                }
        }
}

-------------------------------------------------------------------------------------------------------------------

On Fri, Aug 12, 2011 at 6:00 AM, 이희승 (Trustin Lee) <trustin at gmail.com>wrote:

> Could you also post the non-Netty code that works?  I also would suggest
> you to remove the decoder from the pipeline just in case of the buggy
> decoder.
>
> --
> Trustin Lee <http://gleamynode.net/>
>
> On Thursday, August 11, 2011 at 10:50 PM, alex_ab_sw wrote:
>
> Hello,
>
> I am trying to write a component in an application that will listen on UDP
> for multicast messages, but somehow I don't receive any messages while with
> a MulticastSocket I can see the messages landing fine.
>
> Here is the piece of code that I am talking about:
> ---------------------------------------------------------------
> DatagramChannelFactory channelFactory = new
> OioDatagramChannelFactory(Executors.newCachedThreadPool());
> ConnectionlessBootstrap bootstrap = new
> ConnectionlessBootstrap(channelFactory);
>
> bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
> @Override
> public ChannelPipeline getPipeline() {
> return Channels.pipeline(messageDecoder, multicastHandler);
> }
> });
>
> bootstrap.setOption("receiveBufferSizePredictorFactory", new
> FixedReceiveBufferSizePredictorFactory(
> maxPacketSize));
>
>
> logger.info("... binding the DatagramChannel on new
> InetSocketAddress {}:{}", localIpAddress, multicastPort);
> DatagramChannel datagramChannel = (DatagramChannel)
> bootstrap.bind(new InetSocketAddress(localIpAddress,
> multicastPort));
>
> try {
> InetAddress multicastAddress =
> InetAddress.getByName(multicastIpAddress);
> datagramChannel.joinGroup(multicastAddress);
> } catch (UnknownHostException e) {
> shutdown();
> }
> ------------------------------------------------------------
> Can you tell if I am doing something wrong, because I see no errors on logs
> but also no messages coming. The component is deployed on a Linux box with
> CentOS on it.
>
> Thanks in advance.
>
> --
> View this message in context:
> http://netty-forums-and-mailing-lists.685743.n2.nabble.com/UDP-Listener-tp6676456p6676456.html
> Sent from the Netty User Group mailing list archive at Nabble.com.
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-- 
Have fun & travel light.
Alex
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