Linked Open Data Principles, Technologies and Examples

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SUPPORT
OPEN
Linked Open Data
Principles,
Technologies and
Examples
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Learning objectives
By the end of the course, participants should have a clear
understanding of:
• What linked open data is;
• What is the difference between linked and open data;
• How to publish linked data;
• The economic and social aspects of linked data;
• How linked data technologies can be applied to improve the
availability, understandability and usability of EU data.
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Content
This training consists of 3 modules:
1. Introduction to linked data
2. Introduction to RDF & SPARQL
3. Workshop on publishing open linked EU data
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Learning Module 1:
Introduction to Linked Data
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Introduction to linked data
This module contains ...
• An introduction to the linked data principles;
• The expected benefits of linked data;
• An introduction to linked data technologies;
• An outline of the 5-star scheme for publishing linked data;
• An overview of linked data initiatives in Europe.
Slide 5
Find more on: training.opendatasupport.eu

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What is linked data?
Evolution from a document-based Web to a Web of
interlinked data.
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The Web is evolving from a “Web of linked
documents” into a “Web of linked data”
• The Web started as a collection of
documents published online – accessible at a
Web location identified by a URL.
• These documents often contain data about
real-world resources which is mainly
human-readable and cannot be understood
by machines.
• The Web of Data is about enabling the access
to this data, by making it available in
machine-readable formats and connecting it
using Uniform Resource Identifiers (URIs),
thus enabling people and machines to collect
the data, and put it together to do all kinds
of things with it (permitted by the licence).
Machine-readable data
(or metadata) is data in a
format that can be interpreted
by a computer.
2 types of machine-readable
data exist:
• human-readable data that
is marked up so that it can
also be understood by
computers, e.g.
microformats, RDFa;
• data formats intended
principally for computers,
e.g. RDF, XML and JSON.
Slide 7
See also:
http://www.ted.com/talks/tim_berners_lee_on_the_next_web.html
http://linkeddatabook.com/editions/1.0/

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Defining linked data
Providing data as a service
“Linked data is a set of design principles for sharing machine-readable
data on the Web for use by public administrations, business and
citizens.”
EC ISA Case Study: How Linked Data is transforming eGovernment
The four design principles of Linked Data (by Tim Berners Lee):
1. Use Uniform Resource Identifiers (URIs) as names for things.
2. Use HTTP URIs so that people can look up those names.
3. When someone looks up a URI, provide useful information, using the
standards (RDF, SPARQL).
4. Include links to other URIs so that they can discover more things.
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See also:
http://www.youtube.com/watch?v=4x_xzT5eF5Q
http://www.w3.org/DesignIssues/LinkedData.html
http://www.youtube.com/watch?v=uju4wT9uBIA

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The value proposition of linked (open)
government data
• Flexible data integration: facilitates data integration and enables
the interconnection of previously disparate government datasets.
• Efficiency gains in data integration– the network effect: the
addition of each new dataset increases the value of those datasets
that are already published!
• Ease of navigation: makes browsing through complex data easier
via URIs.
• Increase in data quality:
 The use of URIs leads to improved data management and quality.
 The increased (re)use triggers a growing demand to improve data quality.
Through crowd-sourcing and self-service mechanisms, errors are
progressively corrected.
9
See also:
ISA Study on Business Models for LOGD
https://joinup.ec.europa.eu/community/semic/document/study-
business-models-linked-open-government-data-bm4logd

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government data
• Increase in data usability by providing data as a service:
 Resolvable URIs
 Data is available in different formats, not limited to RDF, e.g. XML, CSV,
text, JSON…
• Compatible with existing standards and technologies: a
linked data infrastructure can provide access to homogenised,
linked, and enriched data using standard Web-based interfaces
(such as HTTP and SPARQL) and Web-based languages (such as
XHTML, RDF+XML), on top of either:
 Existing relational/spatial database systems, by applying database-to-RDF
conversions; or
 Existing XML/file-based data.
10

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government data
• Ease of model updates: RDF data models and vocabularies can be
extended, adapted and updated more easily. Changes can be reflected
on the data with lower costs and effort (compared to traditional
relational databases).
• Cost reduction: The reuse of LOGD in e-Government applications
leads to considerable cost reductions, when it comes to service
integration, data use, reuse, and exchange.
• New services: The availability of LOGD gives rise to new,
integrated, services offered by the public and/or private sector.
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See also:
https://joinup.ec.europa.eu/community/semic/document/study-
business-models-linked-open-government-data-bm4logd

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The four principles of linked data in practice
1. Use Uniform Resource Identifiers (URIs) as names for things.
2. Use HTTP URIs so that people can look up those names.
E.g. for an organisation: UNICEF in EuroVoc.
- http://eurovoc.europa.eu/1022
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The four principles in practice
3. When someone looks up a URI, provide useful information, using the
standards (RDF, SPARQL).
4. Include links to other URIs so that people/machines can discover more
things.
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Enablers of Linked Open Government Data
• Forward-looking strategies. Alignment with modern techniques
as a way to maintain reputation as leaders in the domain.
• Open licensing and free access: an advantage contributing to
the popularity of LOGD.
• Ease of data model updates to include new data or connect data
from different sources.
• Enthusiasm from ‘champions’.
• Emerging best practice guidance: dissemination of best
practices to create common approaches and reduce the risk in
implementation.
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See also:
https://joinup.ec.europa.eu/community/semic/document/study-business-
models-linked-open-government-data-bm4logd

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Linked data vs. open data
Open data
Data can be published and be
publicly available under an open
licence without linking to other
data sources.
Linked data
Data can be linked to URIs from
other data sources, using open
standards such as RDF without
being publicly available under an
open licence.
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“Open data is data that can be freely used, reused and redistributed by
anyone – subject only, at most, to the requirement to attribute and share-
alike.”
- OpenDefinition.org
See also:
Cobden et al., A research agenda for Linked Closed Data
http://ceur-ws.org/Vol-782/CobdenEtAl_COLD2011.pdf

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Linked data foundations
URIs for naming things, RDF for describing data and
SPARQL for querying linked data.
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Uniform Resource Identifier (URI)
“A Uniform Resource Identifier (URI) is a compact sequence of characters that
identifies an abstract or physical resource.”
– ISA’s 10 Rules for Persistent URIs
A country, e.g. Belgium
- http://publications.europa.eu/resource/authority/country/BEL
An organisation, e.g. the Publications Office
- http://publications.europa.eu/resource/authority/corporate-body/PUBL
A dataset, e.g. Countries Named Authority List
- http://publications.europa.eu/resource/authority/country/
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BE
See also:
http://www.slideshare.net/OpenDataSupport/design
-and-manage-persitent-uris

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RDF & SPARQL
The Resource Description Framework (RDF ) is a syntax for representing
data and resources on the Web
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RDF breaks every piece of information down in triples:
• Subject – a resource, which is identified with a URI.
• Predicate – a URI-identified reused specification of the relationship.
• Object – a resource or literal to which the subject is related.
SPARQL is a standardised language for querying RDF data.
http://example.org/place/Brussels is the capital of “Belgium”.
OR
http://example.org/place/Brussels is the capital of http://example.org/place/Belgium.
Subject Predicate Object
See also:
http://www.slideshare.net/OpenDataSupport/introduction-to-rdf-sparql

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How to publish linked data?
Paving the way towards 5-star linked data
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5 star-schema of Linked Open Data
★
Make your stuff available on the Web (whatever format)
under an open license.
★★
Make it available as structured data (e.g., Excel instead of
image scan of a table).
★★★ Use non-proprietary formats (e.g., CSV instead of Excel).
★★★★
Use URIs to denote things, so that people can point at your
stuff.
★★★★★ Link your data to other data to provide context.
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★ Make your stuff available on the Web under an
open licence
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Trends, risks and
vulnerabilities in
securities markets

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★ ★ Make it available as structured data
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Waterbase - Emissions to water:
CountryCode

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★ ★ ★ Use non-proprietary formats
• Proprietary: Excel, Word, PDF...
• Non-proprietary: XML, CSV, RDF, JSON, ODF...
DG Enlargement - Regional programmes:
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★ ★ ★ ★ Use URIs to denote things
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See also:
http://www.slideshare.net/OpenDataSupport/design-and-manage-persitent-uris
Food Additives - http://open-data.europa.eu/en/data/dataset/1gXgb0Yj73R4ttDChQ5Wyg

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★ ★ ★ ★ ★ Link your data to other data to provide
context
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Corporate bodies Named Authority Lists - http://open-data.europa.eu/en/data/dataset/corporate-body

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LOGD roadblocks
• Necessary investments.
• Lack of necessary competencies.
• Perceived lack of tools.
• Lack of service level guarantees.
• Missing, restrictive, or incompatible licences.
• Surfeit of standard vocabularies.
• The inertia of the status quo – change is accomplished slowly.
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See also:

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Linked data initiatives in
Europe
Examples on supra-national, national, regional and
private initiatives in the area of linked data.
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EU institutions initiatives – some examples
European Environment Agency SPARQL endpoint:
Tool allowing searching for linked data published by the the European Environment
Agency. http://semantic.eea.europa.eu/sparql
EU Open Data Portal SPARQL endpoint:
Tool allowing searching for the metadata stored in the EU Open Data Portal triple store.
https://open-data.europa.eu/en/linked-data
DG SANTE SPARQL endpoint:
Tool for querying linked open data on European Community Health Indicators, the EU
Register of Health Claims, etc. http://ec.europa.eu/semantic_webgate/
Europeana SPARQL endpoint:
Tool allowing querying a multi-lingual online collection of millions of digitized items from
European museums, libraries, archives and multi-media collections.
http://labs.europeana.eu/api/linked-open-data-SPARQL-endpoint
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Initiatives funded by the European Commission
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ADMS.
SW
CORE
VOCABULARY
PUBLIC
SERVICE

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Member State initiatives – some examples
DE – Bibliotheksverbund Bayern
Linked data from 180 academic libraries in Bavaria, Berlin and Brandenburg.
IT – Agenzia per l’Italia digitiale
Three datasets published as linked data: the Index of Public Administration, the SPC
contracts for web services and conduction systems and the Classifications for the data in
Public Administration.
NL – Building and address register
The Dutch Address and Buildings base register published as linked data.
UK – Ordnance Survey
Three OS Open Data products published as linked data: the 1:50 000 Scale Gazetteer,
Code-Point Open and the administrative geography taken from Boundary Line.
UK – Companies House
Publishing basic company details as linked data using a simple URI for each company in
their database.
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See also:

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Non-governmental applications
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Conclusions
• Linked data is a set of design principles for sharing machine-readable
data on the Web.
• URIs, RDF and SPARQL form the foundational layer for Linked data.
• Linked data offers a number of advantages such as:
o Data integration with small impact on legacy systems;
o Enables for semantic interoperability;
o Easier browsing through complex data;
o Increased data quality;
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Conclusions cont’d
• Linked data offers a number of advantages such as:
o Enables easy updates, adaptations and extensions of data models;
o Cost reduction from the reuse of LOGD in e-Government applications;
o Enables creativity and innovation through context and knowledge-
creation.
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Learning Module 2:
Introduction to RDF & SPARQL
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Introduction to RDF and SPARQL
This module contains ...
• An introduction to the Resource Description Framework (RDF) for
describing your data.
• An introduction to SPARQL on how you can query and manipulate
data in RDF.
Slide 35
Find more on: training.opendatasupport.eu

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Learning objectives
By the end of this training module you should have a clear understanding
of:
• The Resource Description Framework (RDF);
• How to write/read RDF;
• How you can describe your data with RDF;
• What SPARQL is;
• How to understand and write a SPARQL SELECT query.
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Resource Description Framework
An introduction to RDF.
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RDF in the stack of Semantic Web technologies
Resource: Everything that can have
a unique identifier (URI), e.g. pages,
places, people, organisations,
products...
Description: attributes, features,
and relations of the resources
Framework: model, languages and
syntaxes for these descriptions
• Published as a W3C
recommendation in 1999.
• RDF was originally introduced as a
data model for metadata.
• RDF was generalised to cover
knowledge of all kinds.
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Example: RDF description of an organisation
Publications Office, 2, rue Mercier, 2985 Luxembourg, LUXEMBOURG
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<rdf:RDF
xmlns:rdfs=“http://www.w3.org/2000/01/rdf-schema#”
xmlns:org=“http://www.w3.org/ns/org#”
xmlns:locn=“http://www.w3.org/ns/locn#” >
<org:Organization rdf:about=“http://publications.europa.eu/resource/authority/corporate-
body/PUBL”>
<rdfs:label> “Publications Office”< /rdfs:label>
<org:hasSite rdf:resource=“http://example.com/site/1234”/>
</org:Organization>
<locn:Address rdf:about=“http://example.com/site/1234”/>
<locn:fullAddress>”2, rue Mercier, 2985 Luxembourg, LUXEMBOURG”</locn:fullAddress>
</locn:Address>
</rdf:RDF>

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RDF structure
Triples, graphs and syntaxes.
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What is a triple?
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Every piece of information expressed in RDF is represented as a triple:
• Subject – a resource, which is identified with a URI.
• Predicate – a URI-identified reused specification of the relationship.
• Object – a resource or literal to which the subject is related.
http://publications.europa.eu/resource/authority/file-type/ has a title “File types Name Authority List”.
Subject Predicate Object
Example: name of a dataset:

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RDF Syntax
RDF/XML
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<rdf:RDF
xmlns:dcat=“http://www.w3.org/TR/vocab-dcat/“
xmlns:dct=“http://purl.org/dc/terms/”
<dcat:Dataset rdf:about=“http://publications.europa.eu/resource/authority/file-type/”>
<dct:title> “File types Named Authority List”< /dct:title>
<dct:publisher rdf:resource=“http://open-data.europa.eu/en/data/publisher/publ”/>
</dcat:Dataset>
<dct:Agent rdf:about=“http://open-data.europa.eu/en/data/publisher/publ”/>
<dct:title>”Publications Office”</dct:title>
</dct:Publisher>
</rdf:RDF>
Subject
Predicate
Object
Graph
Definition of prefixes
Description of data – triples

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Visual representation (RDF graph) of the triples from
the RDF/XML syntax example
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Subject
Predicate
Object

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RDF Syntax
Turtle
Subject
Predicate
Object
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@prefix dcat: <http://www.w3.org/TR/vocab-dcat/> .
@prefix dct: <http://purl.org/dc/terms/.
< http://publications.europa.eu/resource/authority/file-type/>
a <dcat:Dataset> ;
dct:title “File types Name Authority List“;
dct:publisher <http://open-data.europa.eu/en/data/publisher/publ> .
<http://open-data.europa.eu/en/data/publisher/publ>
a <dct:Agent> ;
dct:title “Publications Office” .
Graph
See also:
http://www.w3.org/2009/12/rdf-ws/papers/ws11
Definition of prefixes
Description of data – triples

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RDF Syntax
RDFa
Subject
Predicate
Object
Slide 45
<html>
<head> ... </head>
<body>
...
<div resource=“http://publications.europa.eu/resource/authority/file-type/”
typeof= “http://www.w3.org/ns/dcat#Dataset”>
<p>
<span property=" http://purl.org/dc/terms/title ">File types Name Authority List<span>
Publisher: <span property="http://purl.org/dc/terms/Agent"> Publications Office</span>
</p></div>
</body>
See also:
http://www.w3.org/TR/2012/NOTE-rdfa-primer-20120607/
embedding RDF data in HTML

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How to represent data in RDF
Classes, properties and vocabularies
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RDF Vocabulary
“A vocabulary is a data model comprising classes, properties and
relationships which can be used for describing your data and
metadata.”
• Class. A construct that represents things in the real and/or information world, e.g. a
person, an organisation, a concept such as “health” or “freedom”.
• Property. A characteristic of a class in a particular dimension such as the legal name
of an organisation or the date and time that an observation was made. In RDF
properties are encoded as data type properties.
• Relationship. A link between two classes; for example the link between a document
and the organisation that published it (i.e. organisation publishes document), or the
link between a map and the geographic region it depicts (i.e. map depicts geographic
region). In RDF relationships are encoded as object type properties.
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Examples of classes, relationships and properties:
The Core Person Vocabulary in UML
48
class Healthcare Domain
Core Vocabularies::Identifier
dateOfIssue :dateTime [0..1]
identifier :string [1..1]
identifierType :string [0..1]
issuingAuthority :string [0..1]
issuingAuthorityUri :URI [0..1]
Core Vocabularies::Person
alternativeName :string
birthName :string
dateOfBirth :dateTime
dateOfDeath :dateTime
familyName :string
fullName :string
gender :code
givenName :string
patronymicName :string
Core Vocabularies::Location
geographicIdentifier :URI
geographicName :string
Core Vocabularies::Address
addressArea :string
addressID :string
adminUnitL1 :string
adminUnitL2 :string
fullAddress :string
locatorDesignator :string
locatorName :string
poBox :string
postCode :string
postName :string
thoroughfare :string
Core Vocabularies::Geometry
lat :string
long :string
wkt :string
xmlGeometry :XML
address
identifies
geometry
placeOfDeath
countryOfDeath
placeOfBirth
countryOfBirth
identifier
UML: The Unified Modelling Language class diagrams provide the means for expressing
the conceptual data model of vocabularies, such as the ISA Core Vocabularies, thus
facilitating the understanding of the meaning of the data model.
Relationships Class
Properties
Class
Class
Class
Class

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Introduction to SPARQL
The RDF Query Language
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About SPARQL
SPARQL is the standard language to query graph data represented as
RDF triples.
• SPARQL Protocol and RDF Query Language
• One of the three core standards of the Semantic Web, along with RDF
and OWL.
• Became a W3C standard January 2008.
• SPARQL 1.1 is a W3C Recommendation since March 2013.
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Types of SPARQL queries
• SELECT. Return a table of all X, Y, etc. satisfying the following
conditions ...
• CONSTRUCT. Find all X, Y, etc. satisfying the following conditions
... and substitute them into the following template in order to
generate (possibly new) RDF statements, creating a new graph.
• DESCRIBE. Find all statements in the dataset that provide
information about the following resource(s) ... (identified by name or
description)
• INSERT. Add triples to the RDF graph.
• DELETE. Delete triples from the RDF graph.
• ASK. Are there any X, Y, etc. satisfying the following conditions ...
Slide 51
See also:
http://www.euclid-project.eu/modules/chapter2
https://joinup.ec.europa.eu/community/ods/document/tm13-introduction-rdf-sparql-en

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PREFIX dct: <http://purl.org/dc/terms/>
PREFIX dcat: <http://www.w3.org/TR/vocab-dcat/>
SELECT ?title
WHERE
{
?dataset rdf:type dcat:Dataset .
?dataset rdf:title ?title
}
Structure of a SPARQL Query
Slide 52
Type of
query Variables, i.e. what to search for
RDF triple patterns, i.e.
the conditions that
have to be met
Definition of
prefixes

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SELECT – return the name of a dataset with
particular URI
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<http://.../authority/file-type/> rdf:type dcat:Dataset.
<http://.../authority/file-type/> dct:title “File types Name Authority List“ .
<http://.../authority/file-type/> dct:publisher < http://open-data.europa.eu/en/data/publisher/publ>.
< http://.../publisher/publ> rdf:type dct:Agent .
< http://.../publisher/publ> dct:title “Publications Office” .
SELECT ?dataset
WHERE
{
<http://.../authority/file-type/> dct:title ?dataset .
}
dataset
“File types Name Authority List”
Sample data
Query
Result

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SELECT - return the name and publisher of a
dataset
Slide 54
SELECT ?dataset ?publisher
WHERE
{http://.../authority/file-type/ dct:publisher ?publisherURI.
http://.../authority/file-type/ dct:title ?dataset.
?publisherURI dct:title ?publisher . }
dataset publisher
“File types Name Authority List” “Publications Office”
<http://.../authority/file-type/> rdf:type dcat:Dataset.
<http://.../authority/file-type/> dct:title “File types Name Authority List“ .
<http://.../authority/file-type/> dct:publisher < http://open-data.europa.eu/en/data/publisher/publ>.
< http://.../publisher/publ> rdf:type dct:Agent .
< http://.../publisher/publ> dct:title “Publications Office” .
Sample data
Query
Result

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SPARQL Example – EU ODP (1)
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Summary
• RDF is a general way to express data intended for publishing on the
Web.
• RDF data is expressed in triples: subject, predicate, object.
• Different syntaxes exist for expressing data in RDF.
• SPARQL is a standardised language to query graph data expressed
as RDF.
• SPARQL can be used to query and update RDF data.
Slide 58

DATASUPPORTOPEN Slide 59
Learning Module 3:
Workshop for Publishing Open
Linked EU Data

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Workshop for publishing open linked EU data
This module is about...
• Creating an RDF vocabulary for modelling your data.
 How to reuse existing vocabularies to model your data.
 How to create new classes and properties in RDF.
 How and where to publish your RDF vocabulary so that it can be reused
by others.
• An example of how tabular data can be published as Linked Open
Data using Open Refine.
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Learning objectives
By the end of this training module you should have an understanding
of:
• What the best practices are for creating an RDF vocabulary for
modelling your data.
• Where to find RDF vocabularies for reuse.
• How you can create your own RDF vocabulary.
• How to publish your RDF vocabulary.
• The process and methodology for developing semantic agreements
developed by the ISA Programme of the European Commission.
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Creating an RDF vocabulary
How to reuse other vocabularies, define your own terms,
publish and promote your vocabulary
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6 steps for creating an RDF vocabulary
Start with a robust Domain Model developed following a
structured process and methodology.
Research existing terms and their usage and maximise reuse
of those terms.
Where new terms can be seen as specialisations of existing terms,
create sub class and sub properties.
Where new terms are required, create them following
commonly agreed best practice.
Publish within a highly stable environment designed to be
persistent.
Publicise the RDF vocabulary by registering it with relevant
services.
Slide 63
1
See also:
https://joinup.ec.europa.eu/community/semic/document/cookbook-
translating-data-models-rdf-schemas
2
3
4
5
6

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Start with a robust Domain Model
Slide 64
1
has
Ceiling
has
Political
category
Amount
Currency
Figure
Type
Year
Nomenclature
Type
Heading
EU Programme
Code
Type
Political category
Code
Description
Corporate body
Code
Type
Location
Introduction
Remark
Conditions
Acronym
Legal base period
Legal base type
Legal base status
has
Corporate body
has
Nomenclature
has
EU Programme

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General purpose vocabularies: DCMI, RDFS
To name things: rdfs:label, foaf:name, skos:prefLabel
To describe people: FOAF, vCard, Core Person Vocabulary
To describe projects: DOAP, ADMS.SW
To describe interoperability assets: ADMS
To describe registered organisations: Registered Organisation Vocabulary
To describe addresses: vCard, Core Location Vocabulary
To describe public services: Core Public Service Vocabulary
To describe datasets: DCAT, DCAT Application Profile, VoID
Reuse existing terms and vocabularies
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Well-known vocabularies:
Slide 66
DCAT-AP Vocabulary for describing datasets in Europe
Core Person Vocabulary
Vocabulary to describe the fundamental characteristics of
a person, e.g. the name, the gender, the date of birth...
DOAP Vocabulary for describing projects
ADMS Vocabulary for describing interoperability assets.
Dublin Core Defines general metadata attributes
Registered Organisation Vocabulary
Vocabulary for describing organizations, typically in a
national or regional register
Organization Ontology for describing the structure of organizations
Core Location Vocabulary
Vocabulary capturing the fundamental characteristics of a
location.
Core Public Service Vocabulary
Vocabulary capturing the fundamental characteristics of a
service offered by public administration
schema.org
Agreed vocabularies for publishing structured data on the
Web elaborated by Google, Yahoo and Microsoft
See also:
http://www.w3.org/wiki/TaskForces/CommunityProj
ects/LinkingOpenData/CommonVocabulariesReuse existing terms and
vocabularies
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• Reuse greatly aids interoperability of your data
 Use of dcterms:created, for example, the value for which should be a data typed
date such as 2013-02-21^^xsd:date, is immediately processable by many machines.
If your schema encourages data publishers to use a different term and date format,
such as ex:date "21 February 2013" – data published using your schema will require
further processing to make it the same as everyone else's.
• Reuse adds credibility to your schema.
 It shows it has been published with care and professionalism, again, this promotes
its reuse.
• Reuse is easier and cheaper.
 Reusing classes and properties from well defined and properly hosted vocabularies
avoids your having to replicate that effort.
Slide 67
Advantages of reuse:
Reuse existing terms and vocabularies2

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You can find reusable RDF vocabularies on:
Slide 68
http://joinup.ec.europa.eu/ http://lov.okfn.org/
Reuse existing terms and vocabularies2

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Creation of sub-classes and sub-properties
• RDF schemas and vocabularies often include terms that are very
generic.
• By creating sub-class and sub-property relationships, systems
that understand the super property or super class may be able to
interpret the data even if the more specific terms are unknown.
• Do not create sub-classes and sub-properties simply to
allow you to use your own term for something that already
exists.
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Slide 70
3
The EU Budget vocabulary defines the introduction property as a sub-
property of dct:description.
Nomenclature
Type
Heading
Introduction
Remark
Conditions

DATASUPPORTOPEN
Slide 71
3
The EU Budget vocabulary defines the has nomenclature property as a
sub-property of dct:subject.
Amount
Currency
Figure
Type
Year
Nomenclature
Type
Heading
Introduction
Remark
Conditions
has
Nomenclature

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Where new terms are required, create them
following commonly agreed best practices
 Classes begin with a capital letter and are always singular, e.g.
skos:Concept.
 Properties begin with a lower case letter, e.g. rdfs:label.
 Object properties should be verbs, e.g. org:hasSite.
 Data type properties should be nouns, e.g. dcterms:description.
 Use camel case if a term has more than one word, e.g.
foaf:isPrimaryTopicOf.
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If there is no suitable authoritative reusable vocabulary for describing your data, use
conventions for describing your own vocabulary:
- RDF Schema (RDFS)
- Web Ontology Language (OWL)
Example: defining the “Amount” class
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4
See also:
http://www.slideshare.net/OpenDataSupport/model-your-
data-metadata
Amount
Currency
Figure
Type
Year

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If there is no suitable authoritative reusable vocabulary for describing your data, use
conventions for describing your own vocabulary:
- RDF Schema (RDFS)
- Web Ontology Language (OWL)
Example: defining the “amount type” property
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4
See also:
data-metadata
Amount
Currency
Figure
Type
Year

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When defining new properties, consider to define their domain and range.
 A range states that the values of a property are instances of one or more classes.
 A domain states on which classes a given property can be used.
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4
See also:
data-metadata
has
Ceiling
Amount
Currency
Figure
Type
Year
Political category
Code
Description

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Publish within a highly stable environment
designed to be persistent
• Choose a stable namespace for your RDF vocabulary
 Example: http://data.europa.eu/bud/
• Use good practices on the publication of persistent Uniform
Resource Identifiers (URI) sets, both in terms of format, design rules
and management.
 Examples:
o http://www.w3.org/ns/adms
o http://purl.org/dc/elements/1.1
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5
See also:
https://joinup.ec.europa.eu/community/semic/document/cookbook-translating-
data-models-rdf-schemas
http://www.slideshare.net/OpenDataSupport/design-and-manage-persitent-uris

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Publicise the RDF vocabulary by registering it
with relevant services
Once your RDF vocabulary is published you will want people to know about it.
To reach a wider audience, register it on Joinup and Linked Open Vocabularies.
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Conclusions
Slide 78
Start with a robust Domain Model developed following a structured
process and methodology.
Research existing terms and their usage and maximise reuse of those
terms.
Where new terms can be seen as specialisations of existing terms, create
sub class and sub properties as appropriate.
Where new terms are required, create them following commonly agreed
best practice in terms of naming conventions etc
Publish within a highly stable environment designed to be persistent.
Publicise the RDF vocabulary by registering it with relevant services.
Analyse
Model
Publish

DATASUPPORTOPEN
Example
Using Open Refine for RDF to publish tabular data as
Linked Data.
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What is Open Refine
Slide 80
“OpenRefine is a powerful tool for working with messy data, cleaning it,
transforming it from one format into another, ...”
- openRefine.org
See also:
Open Refine website
http://openrefine.org/

DATASUPPORTOPEN
What is Open Refine RDF extension
Open Refine RDF extension allows you to easily import data in different
formats such as :
 CSV;
 Excel(.xls and .xlsx);
 JSON;
 XML; and
 RDF/XML.
And then determine the intended structure of an RDF dataset, by
drawing a template graph.
Slide 81
See also:
LOD 2 Webinar – Open Refine
http://www.youtube.com/watch?v=4Ve93C238gI

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Using Open Refine to model and publish open data
Getting started
1. Install Open Refine from: https://github.com/OpenRefine
2. Install the RDF extension : http://refine.deri.ie/
And then...
Describe your data in a spreadsheet.
Create a project and upload it in Open Refine.
Clean up the data
Map your data to appropriate RDF classes & properties.
Export the data in RDF.
Slide 82
1
2
3
4
5

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Example situation
Publish statistical data as RDF according to RDF
Data Cube Vocabulary
Digital Agenda Scoreboard
Slide 83

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Describe your data in a spreadsheet
Download the tabular data
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1

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Create a project and upload it in Google
Refine
Slide 85
2
Upload the
spreadsheet
Select relevant
tabs
Create the
project

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Clean up the data – table harmonisation
Slide 86
3
• Star & remove unnessary rows
• Rename columns
• Use facets to select the data to
be published

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Clean up the data – prepare RDF
Slide 87
3
• Create URI representation for
the involved object values
• via formula
• via reconsiliation

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Map your data to appropriate RDF classes &
properties (model your data)
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4
Understand the target vocabulary: e.g. W3C RDF Data Cube Vocabulary

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Slide 89
4
Define a skeleton to
transform your spreadsheet
data to RDF

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You can map the data to the ontology using a simple graphical interface to
create or edit an existing RDF skeleton.
You can set the base URI for the data.
Slide 90
Graphical interface to copy/paste an
existing RDF skeleton
Graphical interface to edit an
RDF skeleton
4

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Export your data to RDF/XML or Turtle
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5
Export of the data
in Turtle

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Production pipelines
From desk to automated pipeline
Slide 92
flexibility
volume
OpenRefine
UnifiedViews
Cellar

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Ready to test your knowledge?
Slide 93
You may take the online test
here!

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Thank you for your attention!
...and now YOUR questions?
Slide 94

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References
• 5 ★ Open Data. http://5stardata.info/
• ADMS Brochure. ISA Programme.
https://joinup.ec.europa.eu/elibrary/document/adms-brochure
• An organization ontology. W3C. http://www.w3.org/TR/vocab-
org/ W3C.
• Case study on how Linked Data is transforming eGovernment.
ISA Programme.
https://joinup.ec.europa.eu/community/semic/document/case-
study-how-linked-data-transforming-egovernment
• Common Vocabularies / Ontologies / Micromodels. W3C.
http://www.w3.org/wiki/TaskForces/CommunityProjects/Linki
ngOpenData/CommonVocabularies
• Cookbook for translating Data Models to RDF Schemas. ISA
Programme.
https://joinup.ec.europa.eu/community/semic/document/cookb
ook-translating-data-models-rdf-schemas
• D7.1.3 - Study on persistent URIs, with identification of best
practices and recommendations on the topic for the MSs and the
EC. ISA Programme.
https://joinup.ec.europa.eu/sites/default/files/D7.1.3%20-
%20Study%20on%20persistent%20URIs.pdf
• EUCLID. Course 1: Introduction and Application Scenarios.
http://www.euclid-project.eu/modules/course1
• Linked Data. Tim Berners-Lee.
http://www.w3.org/DesignIssues/LinkedData.html
Slide 95
• Linked Data Cookbook. W3C.
http://www.w3.org/2011/gld/wiki/Linked_Data_Cookbook
• Linking Open Data cloud diagram, by Richard Cyganiak and Anja
Jentzsch. http://lod-cloud.net/
• Module 2: Querying Linked Data. EUCLID. http://www.euclid-
project.eu/modules/course2
• Open Data – An Introduction. The Open Knowledge Foundation.
http://okfn.org/opendata/
• Open Refine: https://github.com/OpenRefine
• RDF Extension: http://refine.deri.ie/
• Resource Description Framework. W3C.
http://www.w3.org/RDF/
• Semantic Web Stack. W3C.
http://www.w3.org/DesignIssues/diagrams/sweb-
stack/2006a.png
• SPARQL Query Language for RDF. W3C.
http://www.w3.org/TR/rdf-sparql-query/

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Further reading
Slide 96
EC ISA, Process and methodology for developing semantic
agreements,
https://joinup.ec.europa.eu/community/core_vocabularies/documen
t/process-and-methodology-developing-semantic-agreements
EC ISA, Cookbook for translating Data Models to RDF Schemas
https://joinup.ec.europa.eu/community/semic/document/cookbook-
translating-data-models-rdf-schemas

DATASUPPORTOPEN
Further reading
EUCLID - Course 1: Introduction and Application Scenarios
EUCLID - Course 2: Querying Linked Data
Learning SPARQL. Bob DuCharme.
http://www.learningsparql.com/
Linked Data Cookbook, W3C Government Linked Data Working
Group
http://www.w3.org/2011/gld/wiki/Linked_Data_Cookbook
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DATASUPPORTOPEN
Further reading
Linked Data: Evolving the Web into a Global Data Space. Tom Heath
and Christian Bizer.
http://linkeddatabook.com/editions/1.0/
Linked Open Data: The Essentials. Florian Bauer, Martin Kaltenböck.
http://www.semantic-web.at/LOD-TheEssentials.pdf
Linked Open Government Data. Li Ding Qualcomm, Vassilios
Peristeras and Michael Hausenblas.
http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6237454
Semantic Web for the working ontologist. Dean Allemang, Jim
Hendler.
http://workingontologist.org/
Slide 98

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Be part of our team...
Slide 99
Find us on
Contact us
Join us on
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Open Data Support
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http://www.opendatasupport.euOpen Data Support
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This presentation has been created by PwC
Authors:
Michiel De Keyzer, Nikolaos Loutas, Jana
Makedonska, Brecht Wyns
Presentation
metadata
Slide 100
Open Data Support is funded by
the European Commission
under SMART 2012/0107 ‘Lot
2: Provision of services for the
Publication, Access and Reuse of
Open Public Data across the
European Union, through
existing open data
portals’(Contract No. 30-CE-
0530965/00-17).
© 2015 European Commission
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Linked Open Data Principles, Technologies and Examples

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