Copyright 2010 Digital Enterprise Research Institute. All rights reserved. Digital Enterprise Research Institute www.deri.i e VoID – Metadata for RDF datasets Richard Cyganiak, Linked Data Research Centre [email protected]http://www.StefanDecker.org/
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Copyright 2010 Digital Enterprise Research Institute. All rights reserved.
What kind of data is there? Examples? Is it up to date? Who publishes it? Where is the SPARQL endpoint? Is there a download? How big is it? What’s the license?
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Datasets
A dataset is a set of RDF triples that are published, maintained or aggregated by a single provider
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Linksets
An RDF link is an RDF triple whose subject and object are described in different datasets
A linkset is a collection of such RDF links between two datasets
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voiD schema
General metadata
Interlinking
Statistics
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General dataset metadata
Leveraging DublinCore: Dataset homepage Publisher Title and description Categorisation Licensing Technical features
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General dataset metadata
:DBpedia a void:Dataset ; dcterms:title "DBPedia” ; dcterms:description "RDF data extracted from Wikipedia” ; dcterms:contributor :FU_Berlin ; dcterms:source <http://dbpedia.org/resource/Wikipedia> ; void:feature <http://www.w3.org/ns/formats/RDF_XML> ; dcterms:modified "2008-11-17"^^xsd:date .
:Geonames a void:Dataset ; dcterms:subject <http://dbpedia.org/resource/Location> .
:GeoSpecies a void:Dataset ; dcterms:license <http://creativecommons.org/licenses/by-sa/3.0/us/> .
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Access metadata
How to access the actual RDF triples: SPARQL endpoints RDF data dumps Root resources URI lookup endpoints OpenSearch description documents
Used by DBpedia, OpenLink, data.gov.uk, … 30% of LOD datasets have VoID metadata The entire LOD Cloud described in VoID:
semantic.ckan.net
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Applications
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Ed Summers’ LOD Graph
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Summary
Metadata for linked datasets For the 4-5 star datasets W3C Interest Group note (VoID 2)
http://www.w3.org/TR/void/ Leverages Dublin Core, FOAF, etc. Used by DBpedia, OpenLink, data.gov.uk, … Used to generate the LOD Cloud diagram The entire LOD Cloud described in VoID: