Andy Piper has been working in the UK for IBM over the last 10 years. He mentioned how the world is getting more interconnected. IBM's future of a smarter world is geting more interconnection, with lots of sensors, and 'intelligence'.
He showed a big slide of data centres, head office, remote offices, sensors, instruments, etc. 10 years ago someone at IBM came up with MQ Telemetry Transport, a protocol for sensors (very limited capabilities) to publish information.
This protocol minimises on the wire bits. Low bandwidth connections, and high latency connections that could be very expensive. The embedded devices may have very limited processing. It's also published royalty-free for ease of adoption by everyone else. The messages are asynchronous. It copes with loss of contact between client and server. Includes constructs in case the client goes away, such as 'hey server, tell everyone X if I go away'.
He compared MQTT to HTTP. MQTT is more efficient for small amounts of data. It's lightweight on CPU and network traffic. MQTT includes distrubtion more easily (1 to 1, 1 to n, etc).
Python has libmosquitto-python bindings, which are provided with the mosquitto server. There are also perl, php, ruby, C, C++ (and more) bindings. http://mqtt.org. Chris Yeoh has setup a MQTT broker at his home for home automation. He's got some gnome applets, mobile devices, website graphs, and sensors all connected together. Another example was a system that had a TV android burglar control system. And using MQTT in a system to drive black taxis around a race track using the mind control gear. Setting up a bunch of ruber ducks to light up when a phone rings.
To get the code, try Really Small Message Broker, rsmb, http://wwww.alphaworks.ibm.com/tech/rsmb. License is free for personal use... Andy was required to mention this because he works for IBM. The source isn't available. Or you could get http://mosquitto.org which is open source, and runs as a daemon. It's IPv4/IPv6 capable. There is Arduino support.
He mentioned http://homecamp.org.uk, and he talked about some home projects. Some people are using MQTT for desktop notifications. Web thermometers. Digital to analgoure readouts. CEIT @ UQ http://ceit.uq.edu.au/content/messaging-protocol-applications. LEGO microscope control.Weather stations.
He then moved onto to talking about messaging in the enterprise. Turns out rsmb can act as a bridge to other brokers. They have some software to hook up several brokers together into some kind of super broker.