title: Push notifications from server to user with PHP/JavaScript
body: <p><strong>Short:</strong> Is there a way to push data from the server to a logged in user session without that user needing to make an HTTP request?</p>
  
  <p><strong>Long(er):</strong> I'm building an HTML5 application, on an Apache/PHP/MySQL server, that could be served to users on mobile devices (or perhaps via a PhoneGap application). </p>
  
  <p>I would like to let the user know when there is new information available from the application, without racking up excessive data charges by forcing that user to execute a call to the server, or requiring AJAX calls (yes I know it could check for a single byte cookie, but I'd rather make it zero).</p>
  
  <p>A good example of this would be sending chat messages between two users on submit from one user to the other.</p>