Summary of MQTT

MQTT (Message Queue Telemetry Transport)

The official Website

http://mqtt.org/

The final version of MQTT is 3.1

• PDF
  http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/MQTT_V3.1_Protocol_Specific.pdf
• HTML
  http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html
• PubSub (publish / subscribe) model

The final version of MQTT-SN (SN or S, Sensor Network) is 1.2

http://mqtt.org/new/wp-content/uploads/2009/06/MQTT-SN_spec_v1.2.pdf

The client is WSN node (Wireless Sensor Network, like ZigBee), and we need broker like MQTT-S Gateway.

The spec sheet for MQTT is only 42 pages long and MQTT-S is only 28 pages long.

PT Informations to Help you Understand Better

Low Latency Messaging for Mobile Apps or When HTTP and Push Notification are Simply Not Enough

• http://www.slideshare.net/henriksjostrand/devmobile-2013-low-latencymessagingusingmqtt
• Good outline.
• It has JS code example.

Building WSN with MQTT, RPi & Arduino

• http://www.slideshare.net/nivertech/zvi-mqtts-foreuc2013
• Example:
• Attached ZigBee (XBee) to Arduino and used it as WSN node.
• Used Raspberry Pi and Beagle Bone as MQTT-S gateway.

MQTT - MQ Telemetry Transport

• http://www.slideshare.net/PeterREgli/mq-telemetry-transport
• Technical explanation.  Very professional.
• Detailed information about the protocol (message format).
• There is a brief explanation about MQTT-S at the end.

Connecting Cars with IoT MQTT

• http://www.slideshare.net/JoeSpeed/connecting-cars-with-mqtt-and-ibm-message-sight-feb-6-2014-joe-speed
• For cars.  It doesn't have anything to do with what we are doing, BUT cars are always interesting.

Important Documents

IBM MQTT RedBook.  

Building Smarter Planet Solutions with MQTT and IBM WebSphere MQ Telemetry

http://www.redbooks.ibm.com/redbooks/pdfs/sg248054.pdf

• Mosquitto
  Free Broker.  http://mosquitto.org/
  It has sources, binary, Windows/Linux, and even Raspberry Pi.  http://mosquitto.org/download/
  Information starts on pg 46 of RedBook.
  Example for Client C Publisher starts on pg 61, and Subscriber starts on pg 65. (it uses Eclipse Paho)
  
• WMQTT
  Java, GUI Client
  Information starts on pg 49 of RedBook.  http://www-01.ibm.com/support/docview.wss?uid=swg24006006
  
• Example for Arduino
  Starts on pg 210.
  Arduino Library: http://knolleary.net/arduino-client-for-mqtt/
  
• Trace
  Starts from pg 238.
  It has example for using WireShark and WMQTT to trace.

Tips

.MQTT uses Network Byte / Bit ordering. (MSB is equal to bit<0>)

However, remaining length is in LSB-MSB order.