*
     * @param <E> the element type of {@link PriorityBlockingQueue}
     * @param initialCapacity the initial capacity of the priority queue
     * @param comparator the comparator for ordering the elements in the priority queue
     * @return a new instance of {@link PriorityBlockingQueue}
     * @see PriorityBlockingQueue#PriorityBlockingQueue(int, Comparator)
     */

topic*               (string)    name of the MQTT topic to publish
username             (string)    MQTT username
password             (string)    MQTT password
qos                  (number)    set the quality of service priority, defaults to '0'
keep_alive_interval  (duration)  keep-alive interval for MQTT connections in s,m,h,d
reconnect_interval   (duration)  reconnect interval for MQTT connections in s,m,h,d