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

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

1

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

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

2

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

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

3

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

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

4

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!

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

5

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)

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

6

Why REST and Linked Data?

• Leverage the Web’s grounding principles and best practices

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

7

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!

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

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

8

attribute1

attributeN attribute2

…/{nodeId}

attribute attribute

../../{nodeid} ../ …/{nodeId}

attribute

../{nodeId}

1 1

aggregation link

../{nodeId}

reference link

Sensor Information Model Sensor object representation

• GET URI information retrieval

• PUTcreation/update

• DELETE deletion

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

9

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

Exploiting the Model - 1 Virtual sensor • software-based sensor whose value derives from physical sensor ones • Advantages:

• Geographical coverage • New sensor type

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

10

Exploiting the Model – 2 Interlinking sensor information • more complex graphs can be built

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

11

sensor/{nodeId}

sensor/{nodeId}

sensor/{nodeId}

InterDataNet Architecture

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

12

IDN Adapter

IDN Service Platform

Information-centric REST APIs ID

N S

ear

ch

IDN

Stu

dio

Sensing Infrastructures

Information repositories

REST and Web Services

Experiment in SmartSantander

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

13

IDN Adapter

IDN Service Platform

Information-centric REST APIs

IDN

Se

arch

IDN

Stu

dio

Web Applications

Users

Apparent Temp. (AT) Web App • VSs for AT in locations like schools, public gardens, hospitals

• AT = + 06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

14

Benefits

• End users • Quality of Life

• Alerts

• Developers • Fast development

process

• Reduced programming skills

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

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

15

06

/03

/20

13

Sm

artS

anta

nd

er K

ick

Off

Mee

tin

g

16

federica.paganelli@unifi.it stefano.turchi@unifi.it