This document discusses linked open data and how to publish data in a standardized, machine-readable format using semantic web technologies. It explains that linked data uses the Resource Description Framework (RDF) to represent information as a graph of interconnected resources identified by URIs. By publishing data according to linked data principles, separate databases can be connected to work as a single global database. The document provides examples of how cultural heritage data from different domains can be represented and linked in RDF, and outlines six steps for publishing linked data on the web.

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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