The technological advances in hardware and software communication technologies are speeding up the path towards the actualization of the Internet of Things. Nonetheless, novel requirements are emerging for the effective and efficient usage of the huge amount of available sensor information and functional capabilities. Several approaches have been proposed for leveraging the Web to this purpose (i.e. Web of Things). In this work, we propose an information-centric approach to enable a Web of Sensors. We combine the principles of Linked Data and Representational State Transfer (REST) architectural style to represent sensors as graphs of URI-addressable information nodes, which can be easily combined and reused for developing novel applications and creating software-based sensors (Virtual Sensors). Our approach relies on the adoption of a web-oriented middleware and information model, called InterDataNet. CREDITS: the graphics used in the presentation are courtesy of: (slide 12 - antenna icon) http://www.oxygen-icons.org/ (slide 12 - db icon) http://barrymieny.deviantart.com/ (slide 12 - globe icon) http://chromatix.deviantart.com/ (slide 13 - desktop icon) http://bluemalboro.deviantart.com/art/Micro-Icon-Set-42295693 (slide 13 - users icon) http://dellustrations.com/work_icons.html (slide 14 - sun icon) http://dapinographics.com/ (slide 14 - water drop icon) http://linux.softpedia.com/developer/Oliver-Scholtz-93.html

1. Towards a Web of Sensors
built with Linked Data
and REST
S. Turchi, L. Bianchi, F. Paganelli, F. Pirri, D. Giuli, “Towards a
web of sensors built with linked data and REST”, 2013 IEEE
14th International Symposium on a World of Wireless,
Mobile and Multimedia Networks, WoWMoM 2013, art. no.
6583491, Madrid, Spain, 4-7 June 2013,
10.1109/WoWMoM.2013.6583491
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2. References
• S. Turchi, L. Bianchi, F. Paganelli, F. Pirri, D. Giuli, “Towards a
Web of Sensors built with Linked Data and REST”, 2nd IEEE
WoWMoM Workshop on the Internet of Things: Smart Objects
and Services (IoT-SoS 2013, colocated with 14th IEEE Int.
Symp. on a World of Wireless, Mobile and Multimedia
Networks (WoWMoM 2013), Madrid, Spain 4-7 June.
• F. Paganelli, S. Turchi, L. Bianchi, L. Ciofi, M.C. Pettenati, F. Pirri,
and D. Giuli, "An information-centric and REST-based
approach for EPC Information Services, Journal of
Communications Software and Systems, vol. 9, no. 1, March
2013
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3. Outline
• Context and Motivation
• Our approach towards a Web of Sensors
• Information-centric model
• Web APIs
• Middleware services
• Ongoing experiment within the SmartSantander
EU project
• Conclusions
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4. Context
• Web of Things
• Ease the end-user
interaction with sensors
and smart objects by
leveraging the Web
• Functionalities for
publishing the sensors’
representation and make
them accessible on the
Web
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5. Motivation
State of the art in the Web of
Things/Web of Sensors (WoS):
• SensorWeb OGC
specifications
• Several research and
implementation proposals
• Web APIs (REST)
• Semantic annotations and links
(Linked Data)
Current limitation
• Poor support to the
development of web
applications in the WoS
• A limitation to access, reuse
and compose sensor data
• i.e. the WoS objective!
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6. Our Proposal
• A graph-based representation of sensors
• Original combination of REST and Linked Data principles
• WoT as a browsable graph of resource nodes
• Uniform Web Interface
• Creation and Execution environment
• Middleware implementing discovery, search, brokering
capabilities
• Design tools (GUI and JavaScript libraries)
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7. Why REST and Linked Data?
• Leverage the Web’s grounding principles and best practices
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What it is… Useful for…
REST
• Architectural style
• Uniform Interface (HTTP verbs)
• It is based on the principles that
make the web scalable
• Lowering entry barriers for web
developers
• Offering lightweight and uniform
API for accessing data
Linked
Data
• A set of best practices for
publishing and connecting data
and their semantics on the Web
• Standard technologies (HTTP, RDF,
XML, …)
• Global browsable information
space, interlinking data coming
from different information sources
• Shared representation of
interlinked data
REST and Linked Data complement each other!

8. IDN Information Model
• Node: an information
element, made by data
(content) and metadata
• URI-addressable
• Relations
• Aggregation
• Reference
• Document: a collection
of IDN Nodes (1..n)
exposed as a web
resource
• Uniform REST interface
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attribute1
attributeN
attribute2
…/{nodeId}
attribute
attribute
../../{nodeid}
../ …/{nodeId}
attribute
../{nodeId}
1 1
aggregation link
../{nodeId}
reference link

9. Sensor Information Model
Sensor object representation
• GET URI information retrieval
• PUTcreation/update
• DELETE deletion
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Different design
choices are allowed!
nodeId
type
battery
sensor/{nodeId}
longitude
latitude
../location
../data_production
date
../{physical_quantity}
value
measurement_unit
1 1
1..n
aggregation link

10. Exploiting the Model - 1
Virtual sensor
• software-based sensor whose value derives from physical sensor ones
• Advantages:
• Geographical coverage
• New sensor type
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11. Exploiting the Model – 2
Interlinking sensor information
• more complex graphs can be built
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sensor/{nodeId}
sensor/{nodeId}
sensor/{nodeId}

12. InterDataNet Architecture
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IDN Adapter
IDN Service
Platform
Information-centric REST APIsIDNSearch
IDNStudio
Sensing
Infrastructures
Information
repositories
REST and Web
Services

13. Experiment in SmartSantander
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IDN Adapter
IDN Service
Platform
Information-centric REST APIs
IDNSearch
IDNStudio
Web Applications
Users

14. Apparent Temp. (AT) Web App
• VSs for AT in locations like schools, public gardens, hospitals
• AT = +
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Benefits
• End users
• Quality of Life
• Alerts
• Developers
• Fast development
process
• Reduced
programming
skills

15. Conclusions
• Approach for easing the building of a Web of Sensors
• Connection to sensors and existing sensor middleware through a
dedicated adapter
• Representation of objects through a graph of URI-addressable
data units
• Thanks to the adoption of REST and Linked Data principles
• Interoperability and scalability
• Tools easing the development of web of sensors applications
• Ongoing work
• Experiment in SmartSantander
• Semantic-enabled search capabilities
• Security Framework
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federica.paganelli@unifi.it
stefano.turchi@unifi.it