ode>GoogleCloudMessaging</code></a> APIs. To use upstream messaging and the new streamlined registration process, you must <a href="../../google/play-services/setup.html">set up</a> the Google Play services SDK.</p>

<p class="note"><strong>Note:</strong> For an example of an XMPP server, see <a href="server.html#xmpp">GCM Server</a>.

<h2 id="gcm">CCS vs. GCM HTTP</h2>

<p>CCS messaging differs from GCM HTTP messaging in the following ways:</p>
<ul>
  <li>Upstream/Downstream messages
    <ul>
      <li>GCM