Virtualisation and Validation of
Smart City Data
Dr Sefki Kolozali
Institute for Communication Systems
Electronic Engineering Department
University of Surrey
Dr Payam Barnaghi
Institute for Communication Systems
Electronic Engineering Department
University of Surrey
1
Things, Data, and lots of it
image courtesy: Smarter Data - I.03_C by Gwen Vanhee
2
We need more linked open data
Sometimes it’s even better if we have:
(near) real-time
linked open data
Streams
The world of IoT and Semantics
5
Semantics & the IoT
− The Semantic Sensor (&Actuator) Web is an extension
of the current Web/Internet in which information is given
well-defined meaning, better enabling objects, devices
and people to work in co-operation and to also enable
autonomous interactions between devices and/or
objects.
6
Semantic Descriptions in Semantic (Web) World
7
Semantic Web these days…
8
Semantic Sensor Web
“The semantic sensor Web enables
interoperability and advanced analytics
for situation awareness and other
advanced applications from
heterogeneous sensors.”
(Amit Sheth et al, 2008)
9
Several ontologies and description models
10
We have good models and description
frameworks;
The problem is that having good
models and developing ontologies is
not enough.
11
Semantic descriptions are intermediary
solutions, not the end product.
They should be transparent to the enduser and probably to the data producer
as well.
12
A WoT/IoT Framework
Semantically
annotate data
6LowPAN
WSN
Network-enabled
Devices
WSN
CoAP
Gateway
CoAP
CoAP
http://mynet1/snodeA23/readTemp?
HTTP
WSN
Semantically
annotate data
HTTP
WSN
WSN
Gateway
MQTT
WSN
MQTT
And several other
protocols and solutions…
13
Publishing Linked Data
14
Understanding the principles of Linked Data
− It really is all about applying Tim Berners Lee's 4 rules to
encourage re-use of data
− use URIs as the names of things
− use HTTP URIs so we can look them up
− provide useful RDF when things are looked up
− link to other URIs to facilitate discovery
15
6 steps to publishing Linked Data
−
−
−
−
−
−
Understand the principles
Understand your data
Choose URIs for Things in your data
Setup your infrastructure
Link to other data sets
Describe and publicize your data
16
Key Points for Publishing Semantic annotations
− We need a model (ontology) – this is often the easy part
for a single application.
− Interoperability between the models is a big issue.
− Express-ability vs Complexity is a challenge
− How and where to add the semantics
− Where to publish and store them
− Semantic descriptions for data, streams, devices
(resources) and entities that are represented by the
devices, and description of the services.
17
Simplicity can be very useful…
18
Complex models are (sometimes) good
for publishing research papers….
But they are often difficult to
implement and use in real world
products.
19
What happens afterwards is more important
− How to index and query the annotated data
− How to make the publication suitable for constrained
environments and/or allow them to scale
− How to query them (considering the fact that here we are
dealing with live data and often reducing the processing
time and latency is crucial)
− Linking to other sources
20
The IoT is a dynamic, online and rapidly
changing world
Annotation for the (Semantic) Web
isPartOf
Annotation for the IoT
Image sources: ABC Australia and 2dolphins.com
21
Make your model fairly simple and modular
SSNO model
22
Semantic descriptions can be fairly
static on the Web;
In the IoT, the meaning of data and
the annotations can change over
time/space…
23
Static Semantics
24
Dynamic Semantics
<iot:measurement>
<iot:type> temp</iot:type>
<iot:unit>Celsius</iot:unit>
<time>12:30:23UTC</time>
<iot:accuracy>80%</iot:accuracy>
<loc:long>51.2365<loc:lat>
<loc:lat>0.5703</loc:lat>
</iot:measurment>
But this could be a function
of time and location;
What would be the
accuracy 5 seconds after
the measurement?
25
Some good existing models:
SSN Ontology
Ontology Link: http://www.w3.org/2005/Incubator/ssn/ssnx/ssn
M. Compton et al, "The SSN Ontology of the W3C Semantic Sensor Network Incubator Group", Journal of Web Semantics, 2012.
26
Dynamic annotations for provenance data
S. Kolozali et al, A Knowledge-based Approach for Real-Time IoT Data Stream Annotation and Processing", iThings 2014, 2014.
27
CityPulse Ontologies: Stream Annotation
Ontology
CityPulse Ontologies: Quality Ontology
CityPulse Ontologies: Complex Event
Processing Ontology
Validation of sensory linked data
31
Validation of Sensory Linked Data
• To check RDF descriptions
• To enable user to validate an ontology or Linked Data
• Undefined classes and properties
• Poorly formed namespaces
• Problematic prefixes
• Literal syntax validation and other
optional heuristics
Related Ontologies and Terms to the SSN Ontology
?
?
?
SSN
6
The architecture of the SSN Validator web
application
Available at: http://iot.ee.surrey.ac.uk/SSNValidation/
A screenshot of the SSN Validation web application
Available at: http://iot.ee.surrey.ac.uk/SSNValidation/
Tag Cloud Representation of the Related Terms
Available at: http://iot.ee.surrey.ac.uk/SSNValidation/
Some examples from the validation :SavedEnergyOf
outputs
•
is NOT defined!
SPITFIRE
ssn:subPropertyOf is used
•
:SavedEnergyOf rdfs:domain :SavedEnergy
instead of rdfs:subPropertyOf
•
•
Wrong URIs have
been used!
IoT.est and SemsorGridEnv
•
•
:value rdf:type owl:ObjectProperty ;
rdfs:domain :OV ;
ssn:subPropertyOf qudt:numericValue ;
rdfs:isDefinedBy <http://spitfire-project.eu/ontology/ns> .
@prefix ssn: <http://purl.org/ifgi/ssn#> .
OntoSensor
•
Needs to be updated: OWL-2
guidelines -
:event_Description
FunctionalDataProperty
a
owl:FunctionalProperty , owl:DatatypeProperty
;
rdfs:domain :Event ;
rdfs:range xsd:string .
Hands on Session!
38
Link for the hands on session:
http://iot.ee.surrey.ac.uk/citypulse/ontologies/sao/sa
opy.html
39
− Thank you.
− EU FP7 CityPulse Project:
http://www.ict-citypulse.eu/
@ictcitypulse
s.kolozali@surrey.ac.uk &
p.barnaghi@surrey.ac.uk