Comparing SOAs for the Internet of Things

Service Oriented Architectures
for the Web of Things
Dominique Guinard
ETH Zurich / SAP Research / MIT Auto-ID Labs
Brown Bag @ Credit Suisse, Zurich, May 30 2011

I, in a Nutshell @ Alma Mater
 2005: Bachelor in CS and  2010 – 2011: Visiting
Management @ Fribourg: Researcher @ MIT:
 Scalable (Java EE) RFID Indoor  Using Cloud-Computing and REST to
Assets Tracking Framework simplify standard RFID software
(RFIDLocator) @ Sun Microsystems applications.
 2006 – 2007: Master Thesis in
Computer Science @ Lancaster:
 SOA for sensor supported interactions
with mobile phones
 2008 – now: Ph.D. @ ETH
Zurich:
 “Integrating the Real-World in the Web
of Things - A Service Architecture to
Support Application Development”

Credit Suisse, May 30, 2011 Dominique Guinard ETH / MIT 2 / 50

I, in a Nutshell @ Work
 2007 – 2011: SAP AG:
 Associate Researcher, SOA (Java EE,
WS-*) for integrating embedded
devices (e.g., machines) and IT
backend systems (e.g., ERPs)
 2007 – 2008: Auto-ID Labs
Zurich:
 « Mobile Internet of Things » project
with Nokia Research.
 2005: Sun Microsystems
 Intern, virtualized Java EE Portal for
Banking Business
 1997 – 2006: GMIPSoft &
Spoker.com:
 Co-founder, developer, manager

[http://www.flickr.com/photos/moragcasey/]

Service Oriented Architectures for the Web of Things? Why? What?

INTRODUCTION AND MOTIVATION

Things? Smart Things!

and tagged objects!
to sensor networks…

From appliances and machines…


The Smart Things Era
 Ubiquitous:
 Home appliances
 Industries
 Smart Cities
 Connected:
 Zigbee, Bluetooth, Wifi


Service Oriented Architecture for Smart Things
 Question:
 How do we enable tech savvys and
companies to create applications on
top of this eco-system?
 Hundreds of different platforms
 Web?
 Scalable (7000 Facebook p/sec.)
 Ubiquitous (from mobile to desktop)
 Well-understood (1.73 Bio. users)
 Idea:
 Propose an SOA for enabling
composite applications with Smart
Things


Motivation: Use Case Enterprise
ERP, SCM, PLM, SRM, CRM
 The manufacturing industry is
facing a number of challenges: DISCONNECT
 Mass customization, last-minute
changes
 Cross-organizations processes Factory/Plant
 … in a very heterogeneous
world.
 Need for increased flexibility
and agility in the manufacturing
process:
 Enable dynamic reconfiguration
and composition Heterogeneous Plant Floor IT Infras.
 Enable shop-floor events to be
integrated to top-floor enterprise
applications (e.g ERP, etc.)
Machinery & Plant Assets


Today’s Menu
1. Motivation
2. Smart Things SOAs:
1. A WS-* Architecture for Smart
Things
2. The Web of Things
3. Physical Mashups
4. Case study: WEB-enabling the
Global RFID Network
5. Conclusion
[http://www.flickr.com/photos/lessio/1346732230/]

Dominique Guinard ETH / MIT

Credit Suisse, May 30, 2011 9 / 50

SOA-Ready Device Integration in Enterprise Systems
 Develop a cross-layer infrastructure
composed of web service enabled
devices (SOA-ready) strongly
coupled with enterprise
applications.
 Leading competitors in the automation
area.
 SAP’s contribution is in the enterprise
integration.


Socrades Integration Infrastructure: DPWS


Device Layer: Device Profile for Web Services
 Based on DPWS:
 Open standard for providing
WS-* Web Services at smart WS-Discovery WS-Eventing
things level
WS-Addressing
 Minimal set of standards WS-MetadataExchange
 Smaller footprint WS-Policy
 Similarities with UPnP but WS-Security
based on WS standards SOAP 1.2
 DPWS = WS + Discovery + WSDL 1.1, XML Schema
Service Description + Security HTTP 1.1
and focus on Eventing UDP
TCP
IPv4/IPv6
 Goal: Embedding DPWS in
devices and even « in silicon »: Devices Profile for Web Services
 Schneider Electric, ABB, ARM (DPWS)
protocol stack


Socrades Integration Infrastructure: DPWS


Creating Workflows With Smart Things


Qualitative Results: Still Rather Heavy
 Still heavy on the embedded
device itself:
 No DPWS on Sun SPOT, Gripper, PLC
yet.
 Maybe just a matter of time?
 Heavy to program services and
clients:
 Have a WSDL, generate stub from
WSDL, databinding (JAXB) and SOAP,
service lookup, etc.
 WS-* Web Services probably not
the best SOA implementation for
Smart Things [11]
 Especially not for tactical, ad-hoc,
applications [6,7]


Thinking about Alternatives: REST?
 Many practical benchmarking
has shown that REST
outperforms WS-* in the IoT field.
 Yazar and Dunkels [10] have
compared both technologies for
wireless sensor networks.

Source [10] Yazar, Dunkels


Thinking about Alternatives
 Study with ~70 developers:
 REST seen as more adapted to smart
things
 REST seen as easier to learn
 => Fosters public innovation

 Security as the biggest drawback
of REST:
 REST offers security over the
communication channel (HTTPS)
 WS-* offers endpoint to endpoint
security (WS-Security)


[http://www.flickr.com/photos/julianbleecker]

Building a Web of Things, piece by piece…

WEB OF THINGS ARCHITECTURE

The Web of Things


REST: The Core of the Web [1,2]

 REST: architecture with 5 constraints
1. Identify resources and links:
 A resource: something, that can and that’s worth, getting a URI and
links
2. Design respresentations
3. Use the uniform interface
4. Bring things to the Internet&Web


Case Study with Sun Spots Resource Identification Hypermedia

1) Resources and Links

Thanks to their atomicity services on embedded devices are
quite adapted 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
 Led Actuator:
http://webofthings.com/spots/2/actuators/led


2) Representation Design Self-Describing Messages Hypermedia

HTML as default, ideal for browsing:
 http://webofthings.com/spots
JSON & JSONp, ideal for mashups

XML, ideal for integration with business systems


3) Interface Design Uniform Interface Self-Describing Messages

 Leverage content negotiation:
 Accept: application/json
 Use the HTTP Verbs extensively:
 GET, PUT, POST, DELETE
 GET http://webofthings.com/spots/2/sensors/temperature
 PUT http://webofthings.com/spots/2/actuators/led/1
 Map status codes:
 200 OK, 201 Created, 400 Bad Request


4) Bringing Things to the Internet&Web:
Smart Gateways [3]
 6lowpan coming quickly:
 Cisco, IPSO, OpenPicus
 HTTP Reverse Proxy
 Hiding IoT proprietary protocols
(Zigbee, Bluetooth, etc.):
 Dongle based
 OSGi modularity
 Installed on residential gateways:
 Wireless routers (OpenWrt)
 NAT
 RESTful Design Process can be
(partially) automated


Quantitative Evaluation
 10’000 requests on the Sun
SPOTs
 1) Embedded Webserver:
 205 ms (97 – 8500)
 Could be improved with a proxy!
 2) Smart Gateway:
 Sync-based (caching)
 4 ms (2 – 49)
 Age max: 300 ms
 Good enough for most sub-
second use cases.


[http://www.flickr.com/photos/docman]

What can we build on top of the Web of Things?

PHYSICAL MASHUPS

Typical WoT Architecture: « Energie Visible »
 Project for a private foundation
for sustainability (cudrefin02.ch)
 Goal: an easily deployable
system for better understanding
consumption:
 Cross-platform
 Web access
 Uses the Plogg sensor nodes
 Smart Gateway provides
RESTful API


« Energie Visible »: Mashup and UIs [4]
 Web UI / Mashup using Javascript (GWT):
 www.webofthings.com/energievisible
 E-Meter iPhone App

[http://www.vs.inf.ethz.ch/res/show.html?what=emeter_demo]


Physical Mashup Editors [5]
• Clickscript:
– Javascript (JQuery / DOJO) based
visual language.
• Added wrappers for WoT
devices:
– SunSPOT, Ploggs, RFID reader

[http://www.clickscript.ch]


A (business-relevant) case-study in RFID

WEB-ENABLING THE GLOBAL RFID NETWORK

EPC Network in a Nutshell


Paint-Point: Complicated applications developments:

 Goal:
 Offer lighter APIs
 Allow integration with IoT devices
(sensors, mobile phones)
 Allow Web 2.0 integration
 Remedy:
 RESTful APIs
 Real-time Web

[www.flickr.com/photos/jgarber/]


EPC Network in a Nutshell


API Design: Addressability & Connectedness

 Resources:
 Locations, Readers, Tagged objects
(EPC), etc.
 Links:
 Every resource is linked to its children.
 And to relevant resources.

http://.../location/migros:basel/reader/warehouse:incoming/time/2009-12-21T13:22:04.000Z/event/EPC


Design: Representations
 Several representations:
 XML: EPCIS standard
 JSON: Web integration
 HTML: browsability
 CSS for browser
 CSS for mobile (IUI)
 Selected through “HTTP content
negotiation”
 Atom feeds for subscription to
queries.


Implementation: EPCIS Web-adapter


Performance Evaluation


Applications

 Easier to build mobile apps
 Easier to build Web apps
(mashup dashboard)
 Shortcomings:
 How about real-time?
 Beyond EPCIS?
 « Reader » push?


Remedy: Real-Time Web in a Nutshell

Current Web Real-Time Web

[Generated with websequencediagrams.com]


HTML 5 Websockets
 Full-duplex in the browser
 Part of the soon standard HTML
5 spec.
 Subscription through Javascript
 Increasing number of browsers
support

[Generated with websequencediagram.com]


Application: Mobile Reader Monitor
 Use-case:
 Scan QR code
 Monitor an RFID reader (via
LLRP/ALE) live from any mobile
browser
 Technology:
 Fosstrak EPC Cloud
 tPusher
 ~20 lines of Javascript compatible with
most mobile browsers


Paint-Point: Complex and expensive back-end
deployments and maintenance

 Goal:
 Reduce installation & maintenance
time and costs:
 Software
 Harware

 Remedy:
 Virtualization & Cloud Computing

[www.flickr.com/photos/sunep]


A Typical EPC Software Deployment…
1 4
5
6
2 3

8
9
7

10

11) Java App Contrainer ~12 software components
12) Java Enterprise SDK for a typical RFID
(e.g., Tomcat)
deployment!!

Remedy: Virtualization
 Test / dev for the EPC Network
locally in 5 minutes
 Virtualized development
environment:
 Eclipse, LLRP Commander, Readers
simulators, WSN simulators, toolkits, etc.
 All Fosstrak components
 Based on VMWare:
 Private Cloud


Remedy: Cloud Computing
 Run your EPC Network server in
5 minutes!
 Cloud appliance:
 Full EPC Network server
 Admin Web interface
 Fully configured Tomcat Instance
 Based on Amazon EC2:
 Public Cloud
 Utility Computing


All together: EPC Cloud Infrastructure


Application: RFID Mashup Editor

[Clickscript.ch]


[http://www.flickr.com/photos/brapke/]

CONCLUSION AND OUTLOOK

Conclusions
 The integration of Smart Things
should be rooted on the best
practices of SOAs
 2 SOA Architectures for
composite applications with
Smart Things:
 WS-*, DPWS-based
 Better security, built-in eventing and
discovery.
 REST
 Better Web integration, easier to use,
more lightweight

 Key-point: looking beyond the
technological hype.


Thanks a lot for your attention
 Dominique Guinard
 Contact details:
www.guinard.org
 Blog:
www.webofthings.com
 Software:
www.webofthings.com/projects
 Papers and articles:
www.guinard.org/publications
 Special thanks to:
 Vlad Trifa, Simon Mayer, Christian
Floerkemeier, Mathias Mueller, Mathias
Fischer and the WoT members…


References All our papers are on: www.guinard.org/publications

1. L. Richardson and S. Ruby. “RESTful Web Services”.
O'Reilly Media, Inc., 2007
2. R. Fielding: “Architectural styles and the design of
network-based software architectures”, 2000
3. S. Mayer, D. Guinard, V. Trifa: “Facilitating Integration and
Interaction of Real-World Services for WoT” Urban IoT
2010
4. M. Weiss, D. Guinard: “Increasing Energy Awareness
Through Web-enabled Power Outlets” MUM 2010
5. D. Guinard: “Mashing up Your Web-Enabled Home”,
Touch the Web 2010


References
6. Pautasso, Cesare, Olaf Zimmermann, and Frank Leymann.
“Restful web services vs. "big" web services: making the right
architectural decision.” WWW '08
7. Pautasso, Cesare, and Erik Wilde. “Why is the Web Loosely
Coupled? A Multi-Faceted Metric for Service Design.”
WWW’09
8. Kindberg, Tim, John Barton, Jeff Morgan, Gene Becker, Debbie
Caswell, Philippe Debaty, Gita Gopal, et al. “People, places,
things: web presence for the real world.” Mob. Netw. Appl. 7,
no. 5 (2002): 365-376.
9. Dominique Guinard, Mathias Fischer, Vlad Trifa
“Sharing Using Social Networks in a Composable Web of
Things.” Proc. of the First IEEE International Workshop on the
Web of Things (WOT2010). Mannheim, Germany, March 2010


References

10. Yazar, D., & Dunkels, A.. Efficient application integration in
IP-based sensor networks. Proceedings of the First ACM
Workshop on Embedded Sensing Systems for Energy-
Efficiency in Buildings (p. 4350). Berkeley, CA, USA.


Backup


Age of Cache


Protecting Access to Things:
Friends and Things (FAT) [9]


Friends and Things: User Interface


Search and Performances

 Finding Services:
 HTML5 Microdata
 RDFa
 WoT Search:
 Google Custom Engine
 Yahoo Search Monkey
 Dyser

 Performances!
 Push vs Pull
 Highly scalable Web-servers
 Node.js
 Grizzly
 Cloud solutions:
 GAE, AWS


Comparing SOAs for the Internet of Things

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