PHP Comet (server side)

Possible duplicate:
Using comet with PHP?

I am writing a social application with an end written in PHP (I am using the FuelPHP framework). I would like to notify the client that an event has occurred on the server in a similar way to what Facebook does for him.

At the moment I'm just using re-polling using AJAX, but I think I could achieve a nicer implementation by using an event on the server to fire before the client.

Using node.js I have achieved this kind of communication with web sockets and the socket.io module.

Is there a way to do this in PHP? Is PHP really inappropriate for this kind of communication? Can I create a node based child process in some way?

This is a lack of knowledge, can anyone point me to a solution that I can investigate?

This code can illustrate what I am trying to do ...

private function initEvents() {

  $events = Event::instance('chat_event_listener');

  $events->register('messageWasReceived', function($message){
    $this->handleMessageReceived($message);
  });

}

public function post_addNewMessage(){

  //Client uses Posts message to this method using AJAX

  $message = \Input::post('message');
  Event::instance('chat_event_listener')->trigger('messageWasReceived', $message);

  return $this->response(array(
    'success' => true,
    'data' => 'TO DO',
  ));

}

private function handleMessageReceived($message){
  $this->firephp->log('Message received on server: ' . $message);
  //notify client
}