Web of Things - Towards Open and Sharable Networks of Embedded Devices

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

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

Electronic things are invading us...
‣ Powerful tiny computers
‣ Sensors & actuators
‣ Web connectivity
‣ Cheap
‣ Ubiquitous


Translation for hackers:
An infinite playground.

YAAAY!

Megaco Modbus
OGC SensorML
Zorro III
AMQP
OPC-UA

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


We need an universal protocol
that is:

simple, lightweight, loosely-
coupled, scalable, flexible

and hopefully... standard

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


WWWWW Social Web
Physical Web
Real-time Web

Semantic Web Programmable Web
Web of Things


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


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)


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


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


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)


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.

OSGi gateway


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]


Clickscript

‣ Javascript-based visual
mashup editor
‣ Firefox plugin/Web app
‣ Based on DOJO/jQuery

www.clickscript.ch


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;


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);
}
});


Err, what about eventing &
streaming ?

The web wasn’t quite made for
that...

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)


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...


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


Messaging


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

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


Messaging JS solution

‣ jQuery - allows HTTP requests from Javascript
‣ reversehttp - allows passing HTTP requests to client


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?


Label: 
Data Format: Integer 
Operation: 
Method: POST 
Address: http://spotmanager:
8081/sunspots/Core2TestSpot/actuators/leds/led1 
Input: Red 
Output: The updated Resource

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)


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!


Thanks for your
attention !

Vlad Trifa
trifa@inf.ethz.ch
http://www.webofthings.com

Web of Things - Towards Open and Sharable Networks of Embedded Devices

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