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    1   /**
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *     http://www.apache.org/licenses/LICENSE-2.0
   10    *
   11    *  Unless required by applicable law or agreed to in writing, software
   12    *  distributed under the License is distributed on an "AS IS" BASIS,
   13    *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   14    *  See the License for the specific language governing permissions and
   15    *  limitations under the License.
   16    */
   17   package org.apache.openejb.server.discovery;
   18   
   19   import java.net.URI;
   20   import java.net.MulticastSocket;
   21   import java.net.InetAddress;
   22   import java.net.DatagramPacket;
   23   import java.util.concurrent.TimeUnit;
   24   import java.io.IOException;
   25   
   26   /**
   27    * @version $Rev$ $Date$
   28    */
   29   public class MulticastSearch {
   30   
   31       private static final int BUFF_SIZE = 8192;
   32   
   33       private final MulticastSocket multicast;
   34   
   35       public MulticastSearch() throws IOException {
   36           this("239.255.3.2", 6142);
   37       }
   38   
   39       public MulticastSearch(String host, int port) throws IOException {
   40           InetAddress inetAddress = InetAddress.getByName(host);
   41   
   42           multicast = new MulticastSocket(port);
   43           multicast.joinGroup(inetAddress);
   44           multicast.setSoTimeout(500);
   45       }
   46   
   47       public URI search(int timeout, TimeUnit milliseconds) throws IOException {
   48           return search(new DefaultFilter(), timeout, milliseconds);
   49       }
   50   
   51       public URI search() throws IOException {
   52           return search(new DefaultFilter(), 0, TimeUnit.MILLISECONDS);
   53       }
   54   
   55       public URI search(Filter filter) throws IOException {
   56           return search(filter, 0, TimeUnit.MILLISECONDS);
   57       }
   58   
   59       public URI search(Filter filter, long timeout, TimeUnit unit) throws IOException {
   60           timeout = unit.convert(timeout, TimeUnit.MILLISECONDS);
   61           long waited = 0;
   62   
   63           byte[] buf = new byte[BUFF_SIZE];
   64           DatagramPacket packet = new DatagramPacket(buf, 0, buf.length);
   65   
   66           while (timeout == 0 || waited < timeout){
   67               long start = System.currentTimeMillis();
   68               try {
   69                   multicast.receive(packet);
   70                   if (packet.getLength() > 0) {
   71                       String str = new String(packet.getData(), packet.getOffset(), packet.getLength());
   72                       URI service = URI.create(str);
   73                       if (service != null && filter.accept(service)) {
   74                           return service;
   75                       }
   76                   }
   77               } finally {
   78                   long stop = System.currentTimeMillis();
   79                   waited += stop - start;
   80               }
   81           }
   82   
   83           return null;
   84       }
   85   
   86       public interface Filter {
   87           boolean accept(URI service);
   88       }
   89   
   90       public static class DefaultFilter implements Filter {
   91           public boolean accept(URI service) {
   92               return true;
   93           }
   94       }
   95   }

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