public MulticastSearch() throws IOException 
{
        this("239.255.3.2", 6142);
}

 public MulticastSearch(String host,
    int port) throws IOException 
{
        InetAddress inetAddress = InetAddress.getByName(host);
        multicast = new MulticastSocket(port);
        multicast.joinGroup(inetAddress);
        multicast.setSoTimeout(500);
}

 public URI search() throws IOException 
{
        return search(new DefaultFilter(), 0, TimeUnit.MILLISECONDS);
}

 public URI search(Filter filter) throws IOException 
{
        return search(filter, 0, TimeUnit.MILLISECONDS);
}

 public URI search(int timeout,
    TimeUnit milliseconds) throws IOException 
{
        return search(new DefaultFilter(), timeout, milliseconds);
}

 public URI search(Filter filter,
    long timeout,
    TimeUnit unit) throws IOException 
{
        timeout = unit.convert(timeout, TimeUnit.MILLISECONDS);
        long waited = 0;
        byte[] buf = new byte[BUFF_SIZE];
        DatagramPacket packet = new DatagramPacket(buf, 0, buf.length);
        while (timeout == 0 || waited <  timeout){
            long start = System.currentTimeMillis();
            try {
                multicast.receive(packet);
                if (packet.getLength()  > 0) {
                    String str = new String(packet.getData(), packet.getOffset(), packet.getLength());
                    URI service = URI.create(str);
                    if (service != null && filter.accept(service)) {
                        return service;
                    }
                }
            } finally {
                long stop = System.currentTimeMillis();
                waited += stop - start;
            }
        }
        return null;
}