title: App Engine Channel API Connection and Disconnection
body: <p>I have read the section, <em>Tracking client connections and disconnections</em>, in the <a href="https://developers.google.com/appengine/docs/java/channel/overview#Tracking_Client_Connections_and_Disconnections" rel="nofollow noreferrer">Channel API for Java</a> documentation.</p>
  
  <p>It has the following code:</p>
  
  <pre><code>// In the handler for _ah/channel/connected/
  ChannelService channelService = ChannelServiceFactory.getChannelService();
  ChannelPresence presence = channelService.parsePresence(req);
  </code></pre>
  
  <p>How would I create a handler for <code>_ah/channel/connected/</code> or <code>_ah/channel/disconnected</code>? I want to notify or alert connected users when a user is disconnected.</p>