oogle:mobile:data&gt;
    <em>JSON payload</em>
&lt;/gcm&gt;
</pre>

<p>The JSON payload for server-to-device is similar to what the GCM http endpoint uses, with these exceptions:</p>
<ul>
  <li>There is no support for multiple recipients.</li>
  <li><code>to</code> is used instead of <code>registration_ids</code>.</li>
  <li>CCS adds the field <code>message_id</code>, which is required. This ID uniquely identifies the message in an XMPP connection. The ACK or NACK from CCS uses the <code>message_id</code> 