title: Progress notifications from HTTP/REST service
body: <p>I'm working on a web application that submits tasks to a master/worker system that farms out the tasks to any of a series of worker instances.  The work queue master runs as a separate process (on a separate machine altogether) and tasks are submitted to the master via HTTP/REST requests.  Once tasks are submitted to the work queue, client applications can submit another HTTP request to get status information about tasks.</p>
  
  <p>For my web application, I'd like it to provide some sort of progress bar view that gives the user some indication of how far along task processing has come.  The obvious way to implement this would be an AJAX progress meter widget that periodically polls the work queue for status on the tasks that have been submitted.  My question is, is there a better way to accomplish this without the frequent polling?</p>
  
  <p>I've considered having the client web application open up a server socket on which it could listen for notifications from the work master.  Another similar thought I've had is to use XMPP or a similar protocol for the status notifications.  (Of course, the master/worker system would need to be updated to provide notifications either way but I own the code for that so can make any necessary updates myself.)</p>
  
  <p>Any thoughts on the best way to set up a notification system like this?  Is the extra effort involved worth it, or is the simple polling solution the way to go?</p>