while(It.hasNext()){
sub_temp = (Subscriber)It.next() ;
sub_impl_temp = (SubscriberImpl)poa.reference_to_servant(sub_temp);
sub_impl_temp.setInstance(instance);
DR = sub_temp.lookup_datareader(topic.get_name());
DR.take_instance_from_subscriber() ;
if(DR.get_listener()!= null ){
DR.get_listener().on_data_available(DR);
}
}