1. Linked Open Data for
“Dummies”
“D i ”
Rajendra Akerkar

2. Outline
 Basics
 Why we need Linked Open Data?
 Publishing Linked Data
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3. Cultural Heritage models
Libraries Archives Museums
Multiple objects shared Hierarchical description Unique objects
cataloguing context Event based description
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4. Challenge : How to mix the data while
g
preserving the special flavor of
each domain ?
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5. Metadata, Vocabularies, Ontologies
Data about data.
Metadata is structured information that
makes it easier to retrieve, use, or manage
heritage information resource.
heritage information resource
 Metadata
 Metadata Mapping
 Meta‐vocabularies
 SKOS
 Dublin Core
 FOAF
 Domain vocabularies
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6. Why opening data?
Data has more value than applications
Data ages like Software applications
g
age like
 Data is more used if it is easier to use it
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7. Open Data
p
“A piece of content or data is open if
A
anyone is free to use, reuse, and
redistribute it — subject only at most to
only, most,
the requirement to attribute and share‐
alike.”
http://opendefinition.org
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8. A sustainable and consequent strategy of
publishing and linking data on the Web
requires the data to be open
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9. Search for
Artists who are born in Norway, displayed
y, p y
their art at exhibitions in Asia
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10. www.vestforsk.no

11. www.vestforsk.no

12. www.vestforsk.no

13. Munch was the first Western artist to have his
pictures exhibited at the National Galleries in Asia
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14. What s the problem?…
What’s the problem?
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15. Current Web = internet + links + documents
The current Web represents information
using:
Natural language (e.g., English, Norwegian, etc.)
Graphics, multimedia
Page layout
P l t
Okay for humans
Oka for h mans
Difficult for machine processing
Diffic lt for machine processing
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16. What is the problem?
 The Web has problems
 People aren’t interested in documents
• They are interested in things
 People can parse documents and
extract meaning
• Web pages are written in HTML
• HTML describes visualization of information
• Computers can’t!
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17. What do we need to do?
 We need to help machines to understand
the Web so machines can help us
understand things
 They can learn what we are interested in
 They can help us better find what we want
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18. How can we do that?
 Besides publishing documents on the
Web
 which computers can’t understand easily
 Let’s publish something that computers
can understand
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19. Current Data on the Web
 Relational Databases
 APIs
 XML
 XLS
 CSV
 …
 Can’t machines and applications already consume that
data on the Web?
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20. Sure!
However, it is available in distinct formats
and data models
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21. Which makes it difficult to integrate data
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22. For example
FIND all the letters of Anna
Rogstad
R t d archived by people who
hi d b l h
live in Bergen
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23. Is there a standard way of
publishing data on the Web?
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24. Yes,
Yes
We have a standardized way of
y
publishing documents on the
Web
HTML
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25. Then why can’t we have a
Th h ’ h
standard procedure of
p
publishing data on the Web?
g
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26. Resource Description Framework (RDF)
 A data model
 A way to model data
 i e Relational databases use relational data model
i.e. Relational databases use relational data model
 RDF is a triple data model
 Labeled Graph
 Subject, Predicate, Object
<Hans > <lives in> <Sogndal>
<Hans > <lives in> <Sogndal>
<Oslo> <is capital of> <Norway>
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27. So does that mean that
S d th t th t
everyone must publish their data
e e yo e p b e d
in RDF?
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28. It is not mandatory…
It is not mandatory
…however we would like
everyone to publish data in
RDF …
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29. An example
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30. Document on the Web
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31. Databases store documents
THINGS have PROPERTIES:
A Photo has a Title, a photographer…, …
ID Name
N Photographer
Ph t h PublisherID ReleasedData
P bli h ID R l dD t
80685-1-nor- Anna L. Szacinski 1 1914
NO Rogstad
… … … … …
This is a THING:
A photograph of Anna Rogstad PublisherID PublisherName
by L. Szacinski, …
1 Riksarkivet
… …
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32. Representing the data in RDF
name Anna Rogstad
photographer
photo L. Szacinski
ID
80685-1-nor-NO
publisher
name
Publisher Riksarkivet
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33. We are on the Web
Everything on the Web is identified by a
URI
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34. Uniform Resource Identifier  URI
 URIs are the base for providing useful Linked Open Data,
h b f d f l k d
 so carefully think the URI scheme you will follow for your entities.
 It is usually a good idea to separate the ontology from the actual data
instances,
 for example the geo.linkeddata.no follows this scheme:
• http://geo.linkeddata.no/ontology/ClassName (for Concepts)
• http://geo.linkeddata.no/ontology/property (for Properties)
• http://geo.linkeddata.no/resource/InstanceName (for data instances)
 Also, the dereferencing method should be decided
 How to serve resources after the consumer of the information has
requested them via HTTP
 303 redirection or hash URIs
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35. So, link the data to other data
name Anna Rogstad
http://www.ar photographer
kivverket.no/v L. Szacinski
ar/...
ID
80685-1-nor-NO
publisher
name
http://www.ark
http://www ark Riksarkivet
Rik ki t
ivverket.no
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36. Now consider the data from http://kvinnesak.no/
http://www.arki Author http://www.ark
vverket.no/../T
akkebrevet
ivverket.no/va
r/...
description
archiver
Thanking
letter
http://…/arc name
hiver
Randi
Blehr
The letter by Anna Rogstad i hi h she
Th l tt b A R t d in which h
appreciates the appointment
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37. Link data further
http://www.a
rkivverket.no Author http://www.ar
/../Takkebrev kivverket.no/v
et ar/...
description name Anna Rogstad
archiver sameAs
Thanking http://www photographer
letter .arkivverke L. Szacinski
t.no/var/...
http://…/a
name
rchiver ID
80685-1-nor-NO
Randi publisher
Blehr
http://www.ar
p name
Riksarkivet
Rik ki t
kivverket.no
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38. Data about Randi Blehr is available as well
b d l h l bl ll
http://www.nrk livedIn http://dbpedia.org/Bergen
.no/sf/...Blehr/
name Randi Blehr
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39. Link more data
http://www.
arkivverket. hasAuthor
no/../Takke http://…/anna-
brevet rogstad
description
archiver
Thanking
letter
http://…/a
name
rchiver
sameAs Randi
Blehr
http://www.nrk livedIn http://dbpedia.org/Bergen
.no/sf/...Blehr
name Randi Blehr
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40. Now link some more data
http://www.
arkivverket. hasAuthor
no/../Takke http://…/anna-
brevet rogstad
description name Anna Rogstad
archiver
Thanking http://www. photographer
letter arkivverket. L. Szacinski
no/var/...
no/var/
http://…/a
name
rchiver ID
80685-1-nor-NO
Randi publisher
sameAs http://www.
Blehr
arkivverket. name
Riksarkivet
Rik ki t
http://www.nrk LivedIn http://dbpedia.org/Bergen
http://www.stortinget.no
.no/sf/...Blehr
name Randi Blehr
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41. Data on the Web that
is in RDF and is linked
to other RDF data is
LINKED DATA
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42. Linked Data makes the Web look like
ONE
GIANT
GLOBAL
DATABASE!
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43. There is a standardize language
SPARQL
to query Linked Data
q y
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44. FIND all the letters of Anna
Rogstad archived by people who
live in Bergen
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45. http://www.
arkivverket. hasAuthor
no/../Takke http://…/anna-
brevet rogstad
description title Anna Rogstad
archiver
Thanking http://www. photographer
letter arkivverket. L. Szacinski
no/var/...
no/var/
http://…/a
name
rchiver ID
80685-1-nor-NO
Randi publisher
sameAs http://www.
Blehr
arkivverket. name
Riksarkivet
Rik ki t
http://www.nrk livedIn http://dbpedia.org/Bergen
http://www.stortinget.no
.no/sf/...Blehr
name Randi Blehr
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46. Who has publish Linked Data so far?
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47. Link data from more than 40 datasets
Make use of more
http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenData
p
than 2 Billion triples!
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48. www.vestforsk.no

49. The Linking Open Data cloud diagram
Link data from more
than 295 datasets
Last updated: 2011‐09‐19
http://richard.cyganiak.de/2007/10/lod/
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50. Linked data ...
publishing data on the Web ...
... to enable integration, linking and reuse
to enable integration linking
across silos
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51. Six Steps to Publishing Linked Data
1. Understand the Principles
2. Model Your Data
2 Model Your Data
3. Choose URIs for Things in your Data
4. Setup Your Infrastructure
4 Setup Your Infrastructure
5. Link to other Data Sets
6. Describe and Publicise your Data
6 D ib d P bli i D t
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52. Linked data
Apply the principles of the Web to publication of data
The Web:
 is a global network of pages
 each identified by a URL
 fetching a URL gives a document
 pages connected by links
 open, anyone can say anything about anything else
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53. Linked data
Apply the principles to the Web to publication of data
The linked data web:
 is a global network of things

 each identified by a URI
 fetching a URI gives a set of statements
 things connected by typed links
g 
 open, anyone can say anything about anything else
Linked data is “data you can click on”
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54. LOD Benefits
 other humans and applications can
 easily access your data using Web technologies
ffollow the links in order to obtain further
f
contextual information
 links to your data and search engine indices
can increase the visibility of your data
y y
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55. The road to open knowledge
p g
begins here!
Thank you !
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