<li>Near-realtime notification to subscribers of messages published to a "subject"</li>
<li>Server-side storage of past messages for replay later to clients</li>
<li>Support for associating a key with a message and for lookup of the most recent message for a given key</li>
<li>Client identification persistence via <ahref="http://www.w3schools.com/html/html5_webstorage.asp">localStorage</a> tokens or in combination with <ahref="https://developers.google.com/appengine/docs/python/users/">Google account signin</a></li>
<li>Complex messages supported via transparent <ahref="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON">JSON</a> serialization</li>
<li>Server-side strict ordering of messages</li>
<li>Client-side message queueing in localStorage and resumption on restart</li>
<li>Message duplication detection and elimination</li>
<li><ahref="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise">Promise</a> support for notification of client -> server operation completion</li>