How to use

cancel

method

in

org.apache.portals.messaging.PortletMessaging

protected void cancelRenderMessage(PortletRequest request, String message)
{
  try
  {
    if (topic == null)
      PortletMessaging.cancel(request, message);
    else
      PortletMessaging.cancel(request, topic, message);
  }
  catch (Exception e)
  {}
}