 any <code>MQTT_CONTROL_PUBLISH</code> messages are received. </p>
<dl class="section pre"><dt>Precondition</dt><dd>mqtt_init must have been called.</dd></dl>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in,out]</td><td class="paramname">client</td><td>The MQTT client.</td></tr>
  </table>
  </dd>
</dl>
<dl class="section attention"><dt>Attention</dt><dd>It is the responsibility of the application programmer to call this function periodically. All functio