title: How to implement Server push / long polling / comet using PHP and Javascript
body: <p>How can I implement the comet / server push design pattern using PHP and Javascript? 
  Essentially what I would like is something like this:</p>
  
  <ul>
  <li>User clicks a 'submit' button</li>
  <li>Javascript shows a message like 'Processing 0 / 100 items'</li>
  <li>Whenever a new item is processed, the php / server pushes out an update, and the javascript changes the message to 'Processing 2/100 items, 3/100 items, and so on'.</li>
  </ul>
  
  <p>How can I do this? Any links/info please?</p>