title: Best way to notify several java applets/applications of a change on a server
body: <p>I need to know the best (fastest) way to have a server (preferably a php based one, but a jsp/servlet one could be set up as well using google app engine) notify several java applets/applications that a change has occurred to the data. </p>
  
  <p>The way i am picturing this to work will be very similar to that of the way i think an online java game (like Runescape) works<br>
  <em>User 1</em>: Changes data on server.<br>
  <em>Server</em>: returns success to User 1, notifies connected computers of change.<br>
  <em>Connected Computer 1</em>: processes change, returns success to server.<br>
  <em>Connected Computer 2</em>: processes change, returns success to server.<br>
  <em>Connected Computer 3</em>: processes change, returns success to server.<br>
  <em>Connected Computer 4</em>: processes change, returns success to server.   </p>
  
  <p>I am hoping to have this entire process complete in half a second, and not involve polling as there will be long durations of nothing, followed by a sudden moment where 4 events happen in succession. </p>