Presentation given at the 3rd International Conference on Ambient Systems, Networks and Technologies August 27-29, 2012, Niagara Falls, Ontario, Canada. The paper is available on the PORTO open access repository: http://porto.polito.it/2496718/

1. Politecnico di Torino
Dip. Automatica e Informatica
Torino, Italy
The 3rd International Conference on
Ambient Systems, Networks and Technologies
August 27-29, 2012, Niagara Falls, Ontario, Canada
http://elite.polito.it
Publishing LO(D)D:
Linked Open (Dynamic) Data for Smart
sensing and Measuring environments
Fulvio Corno, Faisal Razzak

2. Goals
 Enable sensor networks to publish their data in a
standard way
 Enable distributed applications to consume sensor data
from different sources
 Enable data publication, consumption, computation, re-
publication, etc with minimal effort
 Extend the Linked Open Data cloud with time-varying
(sensor) data streams
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3. Outline
 Context and Motivation
 Proposed Architecture
 Proposed solutions
 Experimental results
 Conclusions
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4. Context
Smart Sensing and Measuring Environments
Smart Homes Sensor and
Smart Factories
Smart Grid Actuator Networks
Environment monitoring
Social mobile applications
Smart Appliances
Affordable and efficient sensors
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5. Context
Smart Sensing and Measuring Environments
Smart Appliances
acceleration
acceleration compass
compass GPS
air pressure proximity
temperature microphone
energy (active, light camera
reactive, reverse,
BT Scan
kVAr, ...)
Affordable and efficient sensors
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6. Context
Smart Sensing and Measuring Environments
Smart Appliances
Affordable and efficient sensors
Motion
RFID
Smoke Pressure
Gyroscope
Proximity 2D codes
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7. Motivation
 Applications need to
Application Application
access information from
multiple environments
 Standard way to publish
Environ Environ Environ
and consume information
ment ment ment  About accessible
environments
Applian Applian Applian  About available applicances,
ces ces ces sensors and their
characteristics
 About the actual data
sensors sensors sensors
measured by sensors
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8. Approach
 Applications need to
Adopt Semantic Web access information from
«Linked Open Data
(LOD)» approach multiple environments
 Standard way to publish
and consume information
Static information:
Can be encoded in RDF  About accessible
according to a public environments
Ontology  About available applicances,
sensors and their
Dynamic information:
characteristics
New approach to represent  About the actual data
streams of RDF events measured by sensors
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9. General LO(D)D Architecture
Smart
Environment Static
Producer publishes
information
Application about sensor
E
streams
G monitors
F
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10. General LO(D)D Architecture
Smart
Environment Static
Producer publishes
information
E Application about sensor
E F
G streams
E
G monitors describes
F
E Sensor
G E
data
F channel
G Sensor
updates F
data
channel
G
Sensor
data
channel
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11. General LO(D)D Architecture
Smart subscribes
Environment Static
Producer publishes information
E Application about sensor Consumer
E F Application
G streams E
E
G monitors describes
F Consumer
E
E
E Sensor Application
G E E
data
F channel
G Sensor G
Consumer
updates F Application
data F
channel receives
G G
Sensor
data
channel
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12. Proposed solutions
Producer  Open source libraries and API to enable
Application
Consumer
Application
application to interact with LO(D)D data
 RDF document with meta-data (PID)
Static
information  Publisher information
about sensor  List of channels, their source data, their
streams
datatypes, and subscription URI/key
E
 RDF «fragments» representing each event
F
G
 Contains: event#, sensor id, timestamp, value,
E unit of measure
Sensor
 Uses publish-subscribe pattern as
data transport mechanism for distributing RDF
channel fragments
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13. Publisher Information Document (PID)
 According to lightweight «Publisher» ontology
 Contains declarations of all channels handled by this
publisher – all needed static information
 Gives information to subscribe to channels
 Created by <RDF:Description RDF:about="&Publisher;energymtr">
publisher API <publisher:Location RDF:datatype="&xsd;string">
Torino, Italia</publisher:Location>
 Published over
<publisher:subscribekey>sub-xxxxxx-42904d46dEEEEE
http </publisher:subscribekey>
<publisher:channelName>Energy Meters
</publisher:channelName>
<RDF:type RDF:resource="&Publisher;Channel"/>
</RDF:Description>
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14. Event data fragments
 Indivudual data points encoded in RDF
 Self-consistent information (e.g. Unit of measure)
 Standard syntax and semantics
 Application-independent representation
 Compact <rdf:Description RDF:about = "&publisher;emergymtrChan1">
<publisher:MeterNumber RDF:datatype="&xsd;int">
encodings 231 </publisher:MeterNumber>
available <publisher:Unit RDF:datatype="&xsd;string" >
http://purl.oclc.org/NET/muo/ucum/unit/power-level/
bel-kilowatt</publisher:Unit>
<publisher:hasTimeStamp RDF:datatype="&xsd;dateTime">
2012-02-02T13:06:41.056Z </publisher:hasTimeStamp>
<publisher:hasCurrentValue RDF:datatype ="&xsd;double">
0.3 </publisher:hasCurrentValue>
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</RDF:Description> LO(D)D

15. Cloud based Transport mechanism
 Provides the updates to subscribers whenever publishers
update data
 New RDF fragments are sent to the cloud service
 Maintains list of subscribers
 Handles logic to provide transport from Publisher to
many Subscriber in real time
 It makes the Publisher a “light-weight component”
 Publisher is independent from the number of connected
subscribers
...and others
pubsubhubbub
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16. Publisher and Consumer APIs
 Publisher Library
 Creates PID file an offers it on http
 Creates channels onto cloud service
 Sends updates to channel, encoding it in RDF
 Consumer Library
 Parses PID file and provides channel information
 Subscribes to one or more channels
 Notifies application whenr new data is available, decoding it
from RDF
 Same application may be producer and consumer at the
same time
 Applications need not manage RDF explicitly
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17. Preliminary Experiment
Building Infrastructure
Politecnico di Torino
poliEnergy
PID
Publishes
P
• 126 Electrical
Meters.
• Take reading
every 15 minutes
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18. Preliminary Experiment
Building Infrastructure
Politecnico di Torino
poliEnergy
PID
Publishes C
P
P
• 126 Electrical
Meters. poliEnergy
Aggregator
• Take reading PID
every 15 minutes
• Aggregates reading
into 3 ranges.
• Publishes using 3
channels
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19. Preliminary Experiment
Building Infrastructure
Politecnico di Torino
poliEnergy
PID
Publishes C
P
P
• 126 Electrical
Meters. poliEnergy
Aggregator
• Take reading PID
every 15 minutes
• Aggregates reading
into 3 ranges.
• Publishes using 3
C channels
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20. Conclusions
 Open applications with
open data
 Exploiting existing
standards (RDF and
pub/sub)
 Extensible to different
type of sensor data
 Highly scalable
http://elite.polito.it
fulvio.corno@polito.it
faisal.razzak@polito.it
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21. 21 ANT’2012, Niagara Falls, Canada LO(D)D