Costanza, Enrico

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Web Services & The Internet of ThingsELEC601729 November 2013 Last edit 29 NovemberEnrico CostanzaThe Internet of Things (IoT)• Everything is connected to the internet• Not just computers, smart phones and tablets• ..but also printers, cars, electricity meters, washing machines, refrigerators, thermostats, medicine containers…– Future or present?The Internet of Things & UbiComp• Formal definition? Seems not to be available, yet• Ubiquitous Computing (UbiComp): computational power is everywhere– Research theme started in the 90sIoT and Web Services• Can we use existing web services architectures for the IoT?• Take advantage of available and well understood infrastructure• Easier integration with web applications running on computers, phones and tabletsIoT in Practice• A number of existing "things" are already connected to the Internet– Examples: AlertMe energy monitor, CurrentCost energy monitor, some ambient displays (e.g. Philips multi-colour lamp)– Use existing APIs• Prototyping new devices using microcontrollers (uControllers) and network modulesExample: Networked Electricity Sensor• AlertMe Energy Monitoring kit • Price tag about £50Example: Networked Electricity Sensor• AlertMe Energy Monitoring kit • Price tag about £50Our server Existing company serverRESTRESTInterfacing with AlertMe• Use existing HTTP API defined by AlertMe• Cache and expose the data again in a format that is more compatible with what we needPrototyping New IoT: Microcontrollers• Small embedded computational devices• Include CPU, RAM and a number of peripheralsImage fromhttp://elm-chan.org/works/avrx/rc/avrs.jpeguController vs. Your Usual ComputerStandard Computer uControllerNeeds to be plugged to powerPlug to wall socket: AC at 220V or 110VDC at 2.7V to 5.5V (typically) 3.3V convenientBuilt-in peripheralsVideo card, audio card, network card, …Analog-to-digital converter (ADC), timers, PWM, …Ports USB, FireWire, VGA, HDMI, audio jack sockets, …Serial, I2C, TWI, …External peripherasPrinter, Scanner, External monitor, speakers, …WiFi module, other radio module (BT, ZigBee, ..), Ethernet module, display, motor controllers, relays, …More about uControllers• Several brands and models– Differences in 8-, 16- or 32-bits architecture, computational power, RAM, physical size, built-in peripherals, cost, popularity (=community support?), …• Several programming languages– Assembly, C, C++, …– Abundance of open source libraries• My personal experience: Atmel AVR in plain C (8bits)How to Learn More?• Guess what? ..search on the Internet!• Look at the "instruction manual" of the microcontroller, AKA "datasheet"– Large document,  but don't be intimidated– For example, Atmel AVR ATMega48/88/168 datasheet Arduino as a Prototyping Framework• Open Source prototyping platform, both software and hardware (including IDE) http://arduino.cc/• Originally built around the AVR ATMega168, now expanding to other platforms• C++ based "language" – in reality a collection of libraries• Collection of prototyping boards and extensions ("shields")– Boards include USB to serial converter• Great online community! Wi-Fi Module• Microchip (was Rovio) RN-XV WiFly Module, around £24• Just one example of a radio module, very convenient because it leverages existing ubiquitous infrastructure• Very low power (supposed to run 2 years on 2 AA batteries)Images from:http://www.iaacblog.com/mai/2013/01/beat-glove-proto_2-wifly-osc/ andhttp://www.antratek.com/rn-xv-wifly-moduleWi-Fi Module (cont.)• Serial port interface with simple API  (yet temperamental..)• Documented in the module manual• We can use the serial port interface to connect to a uControllerImages from:http://www.iaacblog.com/mai/2013/01/beat-glove-proto_2-wifly-osc/ andhttp://www.antratek.com/rn-xv-wifly-moduleLet's look at one example!• Connect the WiFi module to the computer– Arduino board used simply as a USB to Serial converter • Try different commands on the WiFi module and see the response  – Join a wireless network– Connect to a server (opens TCP socket) – Make HTTP requests to a Node.js web service• Think about how this task could be done programmaticallyRaspberry Pi?• It is "a tiny and cheap computer for kids"• Somewhere between a uController board and a standard computer– Simplicity vs. complexity– Power consumption– Cost• http://www.raspberrypi.orgImage from http://www.raspberrypi.org/faqsSummary• RESTful web services can be used to implement IoT services and applications• Some existing networked devices ("things") already offer RESTful-ish APIs (e.g. Alertme electricity sensor)• To prototype new connected devices we can use uControllers equipped with WiFi modules• Briefly looked at example requests to existing web service implemented in Node.js

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