MQTT stands for MQ Telemetry Transport. It is a publish/subscribe, extremely simple and lightweight messaging protocol, designed for constrained devices and low-bandwidth, high-latency or unreliable networks. The design principles are to minimise network bandwidth and device resource requirements whilst also attempting to ensure reliability and some degree of assurance of delivery. These principles also turn out to make the protocol ideal of the emerging “machine-to-machine” (M2M) or “Internet of Things” world of connected devices, and for mobile applications where bandwidth and battery power are at a premium.
MQTT was invented by Dr Andy Stanford-Clark of IBM, and Arlen Nipper of Arcom (now Eurotech), in 1999.
MQTT has been widely implemented across a variety of industries since 1999. A few of the more interesting examples are listed here.
As of March 2013, MQTT is in the process of undergoing standardisation at OASIS.
The protocol specification has been openly published with a royalty-free license for many years, and companies such as Eurotech (formerly known as Arcom) have implemented the protocol in their products.
In November 2011 IBM and Eurotech announced their joint participation in the Eclipse M2M Industry Working Group and donation of MQTT code to the proposed Eclipse Paho project.
The “SCADA protocol” and the “MQ Integrator SCADA Device Protocol” (MQIsdp) are both old names for what is now known as the MQ Telemetry Transport (MQTT). The protocol has also been known as “WebSphere MQTT” (WMQTT), though that name is also no longer used.
This is a product from IBM which implements the MQTT protocol in a very scalable manner and which interoperates directly with the WebSphere MQ family of products.
There are other implementations of MQTT listed on here.
Yes. TCP/IP port 1883 is reserved with IANA for use with MQTT. TCP/IP port 8883 is also registered, for using MQTT over SSL.
You can pass a user name and password with an MQTT packet in V3.1 of the protocol. Encryption across the network can be handled with SSL, independently of the MQTT protocol itself (it is worth noting that SSL is not the lightest of protocols, and does add significant network overhead). Additional security can be added by an application encrypting data that it sends and receives, but this is not something built-in to the protocol, in order to keep it simple and lightweight.
The specification and other documentation are available via mqtt.org’s Documentation page.