Talk at http://internet-briefing.ch/devkon

1. Web of Things - Towards Open and
Sharable Networks of Embedded Devices
Internet Developer Summit
7. April 2010
Vlad Trifa - ETH Zurich/SAP Research

2. Disclaimer
2001-2006 Studied Comp. Sci., Robotics, AI, Neurosciences @ EPFL
2005-2006 M.Sc. thesis @ UCLA, Bio-acoustics & Sensor Networks
2006-2007 Research in Humanoid Robotics @ ATR, Kyoto, Japan
2007-now Ph.D. @ ETH Zurich & SAP Research
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

3. Electronic things are invading us...
‣ Powerful tiny computers
‣ Sensors & actuators
‣ Web connectivity
‣ Cheap
‣ Ubiquitous
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

4. Translation for hackers:
An infinite playground.
YAAAY!

5. Megaco Modbus
OGC SensorML
Zorro III
AMQP
OPC-UA

6. Problem...
How do we combine heterogeneous devices to create
interactive ad-hoc applications?
That is, without a
PhD in Computer
Science
‣ Tons of different devices:
‣ Capabilities/functions
‣ Applications/middlewares
‣ Networking protocols
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

7. We need an universal protocol
that is:
simple, lightweight, loosely-
coupled, scalable, flexible
and hopefully... standard

8. Sounds like the Web...
Use Web standards to develop applications for
networked devices.
HTTP, HTML, XML, JSON, RSS, ATOM, MIME,...
‣ TCP/IP & Web granted, WiFi routers ubiquitous
‣ Development of simple Web apps: cheap & quick
‣ Integrate real-world data on the Web
‣ Get features of the Web for free
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

9. WWWWW Social Web
Physical Web
Real-time Web
Semantic Web Programmable Web
Web of Things
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

10. RESTful devices

11. The Web of Things in a nutshell
Steps to create a basic Web of Things (v1.0):
1. Connecting things to the Internet (IPv4/IPv6)
2. Embedded Web servers
3. Make devices part of the Web (using REST)
‣ Model their function as RESTful resources
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

12. Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

13. RESTful SunSPOTs
‣ Properties and functions are
RESTful resources
‣ Devices/services become Web
resources
‣ URI-addressed
‣ Links between them (hateoas)
‣ Different representations (content
negotiation)
‣ Uniform interface (HTTP verbs, status
codes)
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

14. Sunspots resources modeling
Services on embedded devices are adapted for resource oriented
architectures
‣ root: www.spotshost.com
‣ spots list: www.spotshost.com/sunspots
‣ spot #1: www.spotshost.com/sunspots/1
‣ sensors list: www.spotshost.com/sunspots/1/sensors
‣ LEDs : www.spotshost.com/sunspots/1/actuators/leds
‣ LED #1 : www.spotshost.com/sunspots/1/actuators/leds/led1
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

15. Representations
‣ XHTML ideal for browsing
http://webofthings.com/spots
‣ JSON ideal for parsing (& lightweight for
device)
http://webofthings.com/spots.json
‣ XML ideal for business integration
http://webofthings.com/spots.xml
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

16. Uniform interface
‣ HTTP verbs
‣ GET: current temperature
‣ POST: add a timer
‣ PUT: turn a device on/off
‣ DELETE: delete a timer on a device
‣ HTTP headers
‣ Accept header for MIME types
‣ Status codes (200 ok, 401 unauthorized)
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

17. Gateway level integration: Energie Visible
Web / Mobile
Interface
GET http://10.1.1.5:8080/energymonitor/ploggs/*
[{
Gateway "deviceName": "ComputerAndScreen",
(IP:10.1.1.5) "currentWatts": 50.52,
"KWh": 5.835,
"maxWattage": 100.56
},
"deviceName": "Fridge",
"currentWatts": 86.28.,
Sensors
"KWh": 4.421,
(Ploggs)
"maxWattage": 288.92
}, {...}]
Electric
appliances
D. Guinard and V. Trifa. Towards the web of things: Web mashups for embedded devices. In 2nd Workshop on
Mashups, Enterprise Mashups and Lightweight Composition on the Web (MEM 2009), Madrid, Spain, April 2009.
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

18. OSGi gateway
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

19. The era of physical
Mashups

20. Real-world Web applications
REST URL
REST
I
AP
Ja
va
P
ST
PH
Sc
RE
rip
t
[hCp://www.pachube.com] [hCp://www.webothings.com/energievisible] [hCp://www.clickscript.ch]
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

21. Clickscript
‣ Javascript-based visual
mashup editor
‣ Firefox plugin/Web app
‣ Based on DOJO/jQuery
www.clickscript.ch
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

22. Clickscript component
csComponentContainer.push({
name : "cs.web.things.switch",
description : "switch on or off",
inputs : [{name: "IP",type: "cs.type.String"},
{name: "on/off", type: "cs.type.Boolean"}],
outputs: [ ],
image: "web/things/plogg.png",
exec : function(state){
this.setAsync();
var ip = state.inputs.item(0).getValue();
var aurl = "http://"+ip+":8082/EnergieVisible/ploggs/008098e7cb71/status.html";
var onoff = state.inputs.item(1).getValue() ? "on" : "off";
var component = this;
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

23. jQuery HTTP request
$.ajax({
url: aurl,
type: "PUT",
data: ({status : onoff}),
success: function(html){
alert("status of Plogg : " +onoff);
component.finishAsync();
},
error: function(msg){
alert("Error on: "+aurl);
}
});
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

24. Err, what about eventing &
streaming ?
The web wasn’t quite made for
that...

25. Here comes Real-Time Web
‣ Scalable pub/sub for devices is needed
‣ Many solutions (XMPP, etc....)
‣ None really integrate with the Web
‣ ATOM/ATOMpub is RESTful, but not push
‣ Push Web technologies
‣ Apply Web PUSH on devices
‣ Comet & Web hooks
‣ Bi-directional Web messaging (Websockets)
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

26. Data streams
‣ Sensor data represented as Web streams
‣ Publish/subscribe paradigm
‣ Users can create and subscribe to streams
‣ Parameterized
‣ devices
‣ sensors
‣ filter data
‣ sampling frequency
‣ Using REST...
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

27. Messaging implementation
‣ Messages transported in JSON
‣ Message broker as an external entity (outsourced)
‣ Swappable
‣ Scalable
‣ Currently use RabbitMQ
‣ Web integration with pubsubhubbub
‣ RESTful, Web-hook based pub/sub
‣ Support for CometD for Web push
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

28. Messaging
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

29. Request
POST example.org/datastreams/ HTTP/1.1
Content-Type: application/x-www-form-urlencoded
devices=purpleSensor &
data=temperature,light &
frequency=2 &
filter=light < 200 && temperature > 19
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

30. Response
HTTP/1.1 201
[...]
Content-Location: http://example.com:8085/datastreams/bh_0
[...]
Connection: close
‣ Then we just subscribe to it:
curl -vd "hub.mode=subscribe&hub.callback=http://example.com:
8888/client_callback_handler&hub.topic=&hub.verify=sync"
http://example.com:8085/datastreams/bh_0
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

31. Messaging JS solution
‣ jQuery - allows HTTP requests from Javascript
‣ reversehttp - allows passing HTTP requests to client
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

32. function registerDatastream(devices, dataFields, frequency, filter) {
var formData = "devices=" + devices + "&data=" + dataFields;
if (frequency != "") {
formData += "&frequency=" + frequency;
}
if (filter != "") {
formData += "&filter=" + filter;
}
$.ajax( {
type : "POST",
url : “http://example.com:8085/datastreams",
data : formData,
success : function(msg, textStatus, xhr) {
if (xhr.status != 201) {
alert("Error creating datastream: " + xhr.statusText);
} else {
queueURL = msg;
}
},
dataType : "text"
});
}
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

33. function startServerList() {
virtualHost = "vh" + Math.round(Math.random() * 100000);
new HttpServer(virtualHost, function(req) {
if (req.method == "get") {
// subscription verification request
[...]
} else {
// normal message (HTTP POST)
var msg = JSON.parse(req.body);
var light = msg.data[0].light;
var temp = msg.data[0].temp;
alert(“Current light level: “ + light);
req.respond(200, "OK", {}, "");
}
});
}
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

34. Device Discovery
‣ Idea: all device pages contain semantic metadata
‣ Like the header metadata for web robots
‣ Machine-readable user manual
‣ Human-readable documentation
‣ Proposed solution: microformats for devices
‣ What resources are available?
‣ What are their input/output?
‣ What methods are accepted?
‣ Keywords?
‣ Eventing channels?
‣ Maybe documentation?
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

35. <span class="service">
<span class="mftitle">Label: </span><span class="label"></span><br/>
<span class="mftitle">Data Format: </span><span class="data-format">Integer</
span><br/>
<span class="mftitle">Operation: </span><span class="operation"><br/>
<span class="mftitle">Method: </span><span class="method">POST</span><br/>
<span class="mftitle">Address: </span><span class="address">http://spotmanager:
8081/sunspots/Core2TestSpot/actuators/leds/led1</span><br/>
<span class="mftitle">Input: </span><span class="input">Red</span><br/>
<span class="mftitle">Output: </span><span class="output">The updated Resource</
span><br/>
</span>
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

36. Take away notes
‣ It’s time for devices to join the Web
‣ Huge opportunities ahead for WoT
‣ The Web of Things is hard because
‣ People are good Web developers, xor
‣ Good embedded systems developers
‣ Tools & best practices for Web-enabled things are needed
‣ Tradeoff between performance and features
‣ Web developers need to apply their skills and
expertise to build a programmable world
‣ We need applications (deployments)
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

37. More!!!
‣ Some docs: http://www.webofthings.com/sxsw
‣ Play: http://tinyurl.com/sliderswot
‣ Slides: http://www.webofthings.com/talks/idd.pdf
‣ Demos:
‣ Browsing the spot manager
‣ Poster with content negotiation
‣ Javascript app to change LEDs colors
‣ Blink & curl!
Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

38. Thanks for your
attention !
Vlad Trifa
trifa@inf.ethz.ch
http://www.webofthings.com