1. Digital Enterprise Research Institute www.deri.ie
Linked Data & Linked Data Catalogues
Fadi Maali, Deirdre Lee
Copyright 2011 Digital Enterprise Research Institute. All rights reserved.
Enabling Networked Knowledge

2. Open Government Data (OGD)?
Digital Enterprise Research Institute www.deri.ie
 Open Data: data that can be freely used, reused and
redistributed by anyone.*
 Government Data: data and information produced or
commissioned by government or government controlled
entities.*
 Not sensitive or private information but core public data
on transport, infrastructure, education, health, crime,
environment, etc.
*Open Knowledge Foundation (OKF) http://opengovernmentdata.org/what/
Enabling Networked Knowledge

3. Government Data Catalogues
Digital Enterprise Research Institute www.deri.ie
Source: http://datos.fundacionctic.org/sandbox/catalog/faceted/
200 data catalogs
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4. Linked Open Data (LOD)
Digital Enterprise Research Institute www.deri.ie
 What is LOD?
 Use the Web
 Use RDF
 Interlink data
 Why LOD?
 Easy to access… part of the Web
 Use the existing Web of Data to enrich the data context
 Decentralised publishing
Still not a magic bullet though!
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5. Two Key Ingredients
Digital Enterprise Research Institute www.deri.ie
1. RDF – Resource Description Framework
Graph based Data – nodes and arcs
 Identifies objects (URIs)
 Interlink information (Relationships)
 <subject, predicate, object>
2. Vocabularies (Ontologies)
 provide shared understanding of a domain
 organise knowledge in a machine-comprehensible way
 give an exploitable meaning to the data
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6. LOD Cloud
Digital Enterprise Research Institute www.deri.ie
http://lod-cloud.net
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7. Linked Data by Domain
Digital Enterprise Research Institute www.deri.ie
Distribution of triples by
domain
Distribution of links by
domain
http://lod-cloud.net/state
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8. Who is doing LOGD?
Digital Enterprise Research Institute www.deri.ie
Catalonia http://dadesobertes.gencat.cat
Saragossa http://datos.zaragoza.es
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9. Linked Open Metadata
Digital Enterprise Research Institute www.deri.ie
 Describe Catalogues’ contents as Linked Data
 Benefits:
 Accessible
 Increase findability
 Facilitate federated search
 Re-use existing models and tools
 Accurate digital preservation
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10. Federated Catalogues
Digital Enterprise Research Institute www.deri.ie
 Existing federations
 http://logd.tw.rpi.edu/demo/international_dataset_catalog_search
 http://datos.fundacionctic.org/sandbox/catalog/faceted/
 http://opengovernmentdata.org/data/catalogues/
 http://datacatalogs.org/
 http://publicdata.eu/
 http://distillr.com/
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11. Federated Catalogues
Digital Enterprise Research Institute www.deri.ie
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12. Government Data Catalogues
Digital Enterprise Research Institute www.deri.ie
Federated Catalogue
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13. Government Data Catalogues
Digital Enterprise Research Institute www.deri.ie
Solution Components:
• REST interface for Federated Catalogue
communication
• dcat for data model
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14. Data Catalog Vocabulary (dcat)
Digital Enterprise Research Institute www.deri.ie
 Dcat is an RDF vocabulary to represent government
catalogues
 Based on in-depth analysis of seven catalogues from
five countries (early 2010)
 Dcat is on its way to become standardised as a W3C
note by the Government Linked Data working group
 Dcat is being used by data.gov.uk and publicdata.eu
among others - discuss
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15. Data Catalog Vocabulary (dcat)
Digital Enterprise Research Institute www.deri.ie
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16. How to use dcat?
Digital Enterprise Research Institute www.deri.ie
 RDFa
 Embed the RDF data in your HTML pages
 The catalogue web site will be your API as well
 Google understands RDFa
 Data.gov.uk adopts this approach
 RDF dump file
 A downloadable file
 SPARQL endpoint
 A query interface
Enabling Networked Knowledge

17. Asset Description Metadata
Standard (ADMS)
Digital Enterprise Research Institute www.deri.ie
 Apply Linked Data to models
 Examples:
 A list of county names
 A taxonomy of classification categories
 A model to describe persons
 Semic.eu European level metadata repository
 ADMS is an RDF vocabulary for metadata
repositories
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18. Linked Government Data
Digital Enterprise Research Institute www.deri.ie
 Apply Linked Data to the actual dataset content
 Harness the Linked Data benefits to not only the
catalogues but to all your data
 A single dataset can’t tell a full story… interlink your data
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19. LGD Publishing Pipeline
Digital Enterprise Research Institute www.deri.ie
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20. LGD Publishing Pipeline
Digital Enterprise Research Institute www.deri.ie
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21. VoiD
Digital Enterprise Research Institute www.deri.ie
 An RDF Schema vocabulary for expressing metadata
about RDF datasets
Describe datasets and their linking
A Semantic Web Interest Group
Note (W3C)
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22. Pointers
Digital Enterprise Research Institute www.deri.ie
 Dcat
 http://www.w3.org/egov/wiki/Data_Catalog_Vocabulary/Vocabula
ry_Reference
 ADMS
 https://joinup.ec.europa.eu/sites/default/files/ISA_Programme-
ADMS-Brochure_2.pdf
 VoiD
 http://www.w3.org/TR/void/
 Google Refine
 http://code.google.com/p/google-refine/
 http://lab.linkeddata.deri.ie/2010/grefine-rdf-extension/
 http://lab.linkeddata.deri.ie/2011/grefine-ckan/
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