Building the Web of Things with Sun SPOTs Vipul Gupta and David G. Simmons, Sun Labs, Oracle [email protected], [email protected] Ver: 20100921180500 JavaOne 2010, Hands-on Lab Agenda • Background: From the Internet of computers to the Internet of things. • The Web of Things: Vision, relevant technologies, challenges in constrained environments, examples. • Introduction to Sun SPOTs: motivation, features. • Lab overview and exercises: • Sample “Flashlight” application on Sun SPOTs (Ex 1) • RESTful web application on Sun SPOTs (Ex 2) • Exposing the light sensor (Ex 3) and LEDs (Ex 4) as web resources • Access control (Ex 5) 2 Background • People have been connecting “things” to the Internet even before the “Web” More Info: - Trojan room coffee pot http://www.cl.cam.ac.uk/coffee/qsf/coffee.html - Romkey & Hackett’s Internet Toaster, Interop ’90 http://www.savetz.com/yic/YIC11FI_6.html - Robin Southgate, 2001 http://news.bbc.co.uk/2/hi/science/nature/1264205.stm 3 Background • People have been connecting “things” to the Internet even before the “Web” • This trend is accelerating: phones, household appliances, sensor platforms, ambient devices, energy meters, health and fitness devices, asset tracking 4 Background • People have been connecting “things” to the Internet even before the “Web” • This trend is accelerating: phones, household appliances, sensor platforms, ambient devices, energy meters, health and fitness devices, asset tracking • Commercial entities are getting involved • Lots of standards activities: IEEE, IETF, IPSO, OGC, WWW OAuth SensorML Microformats 802.15.4 ROLL 6lowPAN CHTTP SWE EXI RHTTP Webhooks CoRE 5 Background • People have been connecting “things” to the Internet even before the “Web” • This trend is accelerating: phones, household appliances, sensor platforms, ambient devices, energy meters, health and fitness devices, asset tracking • Commercial entities are getting involved • Lots of standards activities: IEEE, IETF, “ IPSO, OGC, WWW • Recognition in mainstream media ’’ 6 Background • People have been connecting “things” to 10 fool-proof predictions for the Internet in 2020 the Internet even before the “Web” 3. The Internet will be a network of things, not computers. • This trend is accelerating: phones, As more critical infrastructure gets hooked up household appliances, sensor platforms, to the Internet, the Internet is expected to ambient devices, energy meters, health become a network of devices rather than a and fitness devices, asset tracking network of computers.Today, the Internet has around 575 million host computers, according to the CIA World Factbook 2009. But the NSF • Commercial entities are getting involved is expecting billions of sensors on buildings and bridges to be connected to the Internet for such uses as electricity and security • Lots of standards activities: IEEE, IETF, monitoring. By 2020, it's expected that the IPSO, OGC, WWW number of Internet-connected sensors will be orders of magnitude larger than the number of users. • Recognition in mainstream media 7 Motivation • Comfort and entertainment -- smart environments (buildings, homes) • Proactive health management -- both people and things (maintenance/repair) • Better efficiency -- resource management (lower cost of heating/cooling) • Timely access to information -- smart phones, environmental sensors • Improved security and peace of mind -- accurate, responsive tracking of valuable assets Connected, smarter living 8 Commercial Opportunities • “Things” or platforms for building “things”: (Arduino, BugLabs, Sun SPOT, TED, Chumby, Nabztag, Nike +iPod, Wattson, sensaware, Crossbow) • Applications (PowerMeter, RunKeeper) • Infrastructure components: gateways, relay services (therecorporation.com, iobridge.com, yaler.org) • Platforms: middle-ware or hosted service for data collection and analysis (Pachube, Sensor.Network) 9 Agenda • Background: From the Internet of computers to the Internet of things. • The Web of Things: Vision, relevant technologies, challenges in constrained environments, examples. • Introduction to Sun SPOTs: motivation, features. • Lab overview and exercises: • Sample “Flashlight” application on Sun SPOTs (Ex 1) • RESTful web application on Sun SPOTs (Ex 2) • Exposing the light sensor (Ex 3) and LEDs (Ex 4) as web resources • Access control (Ex 5) 10 Web Of Things • What? “A vision where everyday devices and objects are integrated into the Web using well-known standards and blueprints (URIs, HTTP, REST).” “Seamless integration of physical and conceptual resources” Also: “The physical web”, “the tactile web” • How? - Connect device to Internet, - Embed web server, - Model resources as URIs 11 REST (Representational State Transfer) • Architectural style of the World Wide Web • "The main idea of REST is to design applications which implement their functionality completely as a set of URI-addressable resources, with HTTP being the [uniform] access method for interacting with them. In such an application, there is no need for any special interface, the application fully blends into the Web ..." -- Erik Wilde, UC Berkeley Putting things to REST More Info: - Roy Fielding’s Ph.D. Thesis (http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm) - REST Wiki (http://rest.blueoxen.net/) 12 REST in a Nutshell • Identify application “resources” using URIs. • Each resource implements some subset of a uniform interface: POST (Create), GET (Read), PUT (Update), DELETE (Destroy). Response codes describe method success/failure. • Representations (XHTML, XML, JSON), conceptually separate from resources, transferred in requests/responses. • Representation includes metadata and links to related resources. 13 REST Examples • Create a new resource, e.g. deploy an application POST /apps HTTP/1.1 Content-Type: application/binary Client Content-Length: 8914 <application binary> Sun SPOT HTTP/1.1 201 Created Location: /apps/SensorSampler • Delete a resource, e.g. undeploy an application Client DELETE /apps/SensorSampler HTTP/1.1 Sun SPOT HTTP/1.1 200 OK 14 REST Examples (cont’d) • Read a resource, e.g. read the light sensor reading GET /light HTTP/1.1 Client Accept: */* Sun SPOT HTTP/1.1 200 OK Content-Type: text/plain Content-Length: 3 138 • Update a resource, e.g. change color of LED 4 PUT /leds/4 HTTP/1.1 Content-Type: text/plain Client Content-Length: 7 Sun SPOT 0,255,0 HTTP/1.1 200 OK 15 REST Benefits • Simplifies integration of resources into the Web, making them accessible as part of a global information system. • Ease building of apps on top of embedded devices, dynamic ad-hoc composite apps involving real-world devices (physical mashups) • “Uniform interface” enables interaction with all sorts of devices via readily available software (browsers, cURL) • “Layered system” supports intermediaries, great for addressing device/ network constraints • Get lots of features for free: caching, linking, security, bookmarking, searching, (HTTP utilized as an application protocol, not just transport). 16 Network Bandwidth Constraints • HTTP, XML are verbose. TCP connection setup/teardown adds overhead. • Use caching, compression via binary encoding, use UDP, e.g. Efficient XML Interchange (http://www.w3.org/XML/EXI/), HTTP header compression (IETF CoRE, draft-tolle- core-ebhttp-00, draft-frank-6lowpan-chopan-00) Sun SPOT Uncompressed Compressed Client GET /spot-5317/temp HTTP/1.1 Accept: */* 13 bytes Host: localhost:8080 0000 - 68 36 47 2f 74 65 6d 70-00 0e 00 00 00 h6G/temp..... Content-Length: 0 User-Agent: curl/7.19.7 ... zlib/1.2.3 HTTP/1.1 200 OK 18 bytes Content-Type: text/plain Cache-Control: max-age=60 0000 - 48 36 40 11 b0 01 0a 00-3c 0e 00 05 00 38 39 2e H6@.....<....89. Content-Length: 5 0010 - 31 35 15 89.15 17 Network Topology Constraints • Device could be behind firewall/NAT, might move • Use relay, with “long-poll” and Reverse HTTP (draft-lentczner-rhttp-00) Sun SPOT Client relay.net POST /spot-5317 HTTP/1.1 Upgrade: PTTH/1.0 Connection: Upgrade Host: relay.net HTTP/1.1 101 Switching Protocols Upgrade: PTTH/1.0 Connection: Upgrade GET /spot-5317/light HTTP/1.1 Host: relay.net GET /spot-5317/light HTTP/1.1 HTTP/1.1 200 OK HTTP/1.1 200 OK Connection: close Connection: close Content-Length: 3 Content-Length: 3 216 216 18 Energy Constraints • Devices sleep periodically to conserve battery • Use sleep-proxy to queue requests, cache responses zz z Sleep z z z proxy z Sun SPOT Client (sleep notification) GET /spots/01AB/temp HTTP/1.1 Cache-Control: max-age=60 HTTP/1.1 200 OK Age: 22 Content-Length: 5 86.45 PUT /spots/01AB/leds/5 HTTP/1.1 Content-Length: 7 0,255,0 HTTP/1.1 202 Accepted Retry-After: 45 Location: spots/01AB/requests/1cqfw 19 Discovery • Finding/understanding what a “thing” provides, relationship to other things • Bootstrapping: Well defined location for metadata (/.well-known, RFC 5785) • Typed links: Use the “rel” attribute in links to describe relationships (draft-nottingham-http-link-header-10), e.g. Link: </>; rel=“http://example.net/foo’’ • Microformats (microformats.org) <div class="vcard"> <div class="fn">Joe Doe</div> <div class="org">The Example Company</div> <div class="tel">604-555-1234</div> <a class="url" href="http://example.com/"> http://example.com/</a> </div> See also: http://hueniverse.com/2009/11/the-discovery-protocol-stack-redux 20 Notifications • Webhooks: an HTTP callback in the form of a POST Client postbin.org Sun SPOT HEAD /spots/01AB/light HTTP/1.1 HTTP/1.1 200 OK Link: </spots/01AB/light/web-hooks>, rel=”subscriptions” POST /spots/01AB/light/web-hooks HTTP/1.1 Notification-Type: