public Requestor(String[] groups,int port,boolean delayFlag) throws IOException {
  super("GS-multicast-discovery-request");
  setDaemon(true);
  sock=new MulticastSocket(Constants.getDiscoveryPort());
  sock.setTimeToLive(multicastRequestConstraints.getMulticastTimeToLive(Constants.getTtl()));
  responsePort=port;
  this.groups=groups == null ? new String[0] : groups;
  this.delayFlag=delayFlag;
}

public Requestor ( String [ ] groups , int port , boolean delayFlag ) throws IOException { super ( "GS-multicast-discovery-request" ) ; setDaemon ( true ) ; sock = new MulticastSocket ( Constants . getDiscoveryPort ( ) ) ; sock . setTimeToLive ( multicastRequestConstraints . getMulticastTimeToLive ( Constants . getTtl ( ) ) ) ; responsePort = port ; this . groups = groups == null ? new String [ 0 ] : groups ; this . delayFlag = delayFlag ; }
create a daemon thread
