var topicDevicesRoot = '$aws/things/kenta-upnp-gateway/devices'
mqttClient.on('connect', function () {
  mqttClient.subscribe(topicDevicesRoot + '/#');
});

mqttClient.on('message', function (topic, buffer) {
  if (topic.indexOf(topicDevicesRoot) === 0){
    executeAction(getContextFromTopic(topic),
        JSON.parse(buffer.toString()));
  } else {
    console.error('MQTT: Unknown message received on topic ' + topic);
    console.error(buffer.toString());
  }
});