A ROA for the WOT

A Resource Oriented Architecture for the Web of Things
Dominique Guinard,ETH Zurich / SAP Research, MIT Auto-ID Labs
Vlad Trifa (ETH Zurich)Erik Wilde (UC Berkeley)

Introduction and Motivation
What’s the Web of Things? Whatisit good for?
Montag, 29. November 2010
2
Departement/Institut/Gruppe
[http://www.flickr.com/photos/moragcasey/]

The Embedded Systems Era
Ubiquitous:
Home appliances
Industries
Smart Cities
Connected:
Zigbee, Bluetooth, Wifi (6lowpan)
D. Guinard ETH / MIT
28.10.2010
ApplicationIntegration?

Finding an Application IntegrationPlateform
Question:
How do weenabletechsavvys and companies to create applications on top of thiseco-system?
Hundreds of differentplateforms.
Web?
Scalable (273 Mio. Tweets / day)
Ubiquitous (from mobile to desktop)
Well-understood (1.73 Bio. users)
Thesis:
Re-use and adapt Web-standards to build a ThingsUniversal API.
4

Today’s Menu
Motivation
Web of Things Architecture:
REST for the Real-World
SyndicatingThings
Using Reverse Proxies
Applications:
Smart Gateway for Smart Meters
PhysicalMashups
Evaluation
Beyond REST
[http://www.flickr.com/photos/lessio/1346732230/]

(INITIAL) Web of Things Architecture
Building a Web of Things, piece by piece…
6
[http://www.flickr.com/photos/julianbleecker]

REST: The Core of the Web in 5 Constraints
A resource: something, that can and that’s worth, getting a URI and links
Resource Identification
Uniform Interface
Self-describing messages
HypermediaDriving Application State
Stateless Interactions
7
Leonard Richardson, and Sam Ruby.
RESTful Web Services.
O'Reilly Media, Inc., 2007.
Fielding, R.T.: Architectural styles and the design of network-based software architectures 2000.

Case Studywith Sun Spots
Thanks to theiratomicity services on embeddeddevices are quiteadapted to Resource-Oriented Architectures.
Resources:
Spots: http://webofthings.com/spots
Spot 2: http://webofthings.com/spots/2
Light Sensor: http://webofthings.com/spots/2/sensors/light
LedActuator: http://webofthings.com/spots/2/actuators/led/
Resource Identification
Hypermedia

Representation Design
HTML as default, ideal for browsing:
http://webofthings.com/spots
JSON & JSONp, ideal for mashups
XML, ideal for integrationwith business systems
Self-Describing Messages
Hypermedia

Interface Design
Leverage content negotiation:
Accept: application/json
Use the HTTP Verbsextensively:
GET, PUT, POST, DELETE
E.g., PUT http://webofthings.com/spots/2/actuators/led/1
Mapstatus codes:
Ok 200, Created 201, Bad Request 400
10
Uniform Interface
Self-Describing Messages

Beyond Client-Server: Real-Time Web
Client-serverparadigm not reallynatural for sensing application.
Need for sensor push.
First step:
Atom / AtomPub
Real push
Pubsubhubbub
11

Smart Gateways: Bringing Things to the Internet
IPv6 lowpancomingquickly:
OpenPicus
HTTP Reverse Proxy
HidingIoTproprietaryprotocols (Zigbee, Bluetooth, etc.):
Donglebased
OSGimodularity
Installed on residentialgateways:
Wireless routers (OpenWrt)
NAT
RESTfulDesign Processcanbe (partially) automated
12
S. Meyer, D. Guinard, V. Trifa: “Facilitating Integration and Interaction of Real-World Services for WoT” UrbanIoT 2010

Applications
Whatcanwebuild on top of the Web of Things?
13
[http://www.flickr.com/photos/docman]

EnablingPhysicalMashups
REST
REST
URL
REST
PHP
REST API
JavaScript
[http://www.pachube.com]
[http://www.webothings.com/energievisible]
[http://www.clickscript.ch]

TypicalWoT Architecture: « Energie Visible »
Project for a privatefoundation for sustainability (cudrefin02.ch)
Goal: an easilydeployable system for betterunderstandingconsumption:
Cross-platform
Web access
Uses the Ploggsensornodes
Smart Gateway providesRESTful API
15

« Energie Visible »: Mashup and UIs
Web UI / MashupusingJavascript (GWT).
E-MeteriPhoneApp.
16
Weiss, M., Guinard, D.: Increasing Energy Awareness Through Web-enabled Power Outlets. MUM 2010
[http://www.vs.inf.ethz.ch/res/show.html?what=emeter_demo]

PhysicalMashup Editors
Clickscript:
Javascript (JQuery / DOJO) based visual language.
Added wrappers for WoT devices:
SunSPOT, Ploggs, RFID reader
17
[http://www.clickscript.ch]

Evaluation
Ok, it’seasier to buildappsupon, but is the WoTreallyfeasible?
18
[ http://www.flickr.com/photos/myfwc]

Quantitative Evaluation
10’000 requests on the Sun SPOTs
Embedded Webserver:
205 ms (97 – 8500)
Smart Gateway:
Sync-based (caching)
4 ms (2 – 49)
Age max: 300 ms
Fairly OK for mostsub-second use cases.
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Beyond REST
Whatis the Web of Things good for?
20
[http://www.flickr.com/photos/brapke/]

Beyond REST, the Web isWaking Up!
Real-time Web:
HTML5 Websockets
HTML5 Server-sent-events
Pubsubhubbub
RESTful XMPP
Service Discovery:
Microformats
HTML5 Microdata
RDFa
21

Thanks a lot for your attention
Contact us if youwant to use our APIs in yourprojects:
Dominique Guinard
www.guinard.org
www.webofthings.com
Specialthanks to: Simon Meyer, Lukas Naef and Thomas Pham.

Backup
23

Qualitative Evaluation
PloggRESTful API & Sun SPOT API used by 6 independentresearchlabs.
Early feedback:
Easy to understand and use
Straightforwardtesting & Web-integration
Currentlyevaluatingwith 80 students.
24

Age of Cache
25

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A ROA for the WOT

by Dominique Guinard on Nov 29, 2010

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