View
137
Download
0
Category
Tags:
Preview:
DESCRIPTION
Citation preview
Copyright 2010 Digital Enterprise Research Institute. All rights reserved.
Digital Enterprise Research Institute www.deri.ie
VoID – Metadata for RDF datasets
Richard Cyganiak, Linked Data Research Centre
Stefan.Decker@deri.orghttp://www.StefanDecker.org/
Digital Enterprise Research Institute www.deri.ie
VoIDVocabulary of Interlinked Datasets
Digital Enterprise Research Institute www.deri.ie
3
W3C Interest Group note
htt
p:/
/ww
w.w
3.o
rg/T
R/v
oid
/
Digital Enterprise Research Institute www.deri.ie
“What business-related datasets are in the LOD Cloud?”
“Which datasets deal with politics and transparency in the EU?”
“We have some DERI data. What could we link it to?”
Digital Enterprise Research Institute www.deri.ie
Read …
http://esw.w3.org/TaskForces/CommunityProjects/LinkingOpenData/DataSets
Digital Enterprise Research Institute www.deri.ie
Click …
Digital Enterprise Research Institute www.deri.ie
Sindice …
Digital Enterprise Research Institute www.deri.ie
Google …
Digital Enterprise Research Institute www.deri.ie
And even if we find a dataset …
Digital Enterprise Research Institute www.deri.ie
Standard questions
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?
Digital Enterprise Research Institute www.deri.ie
Datasets
A dataset is a set of RDF triples that are published, maintained or aggregated by a single provider
Digital Enterprise Research Institute www.deri.ie
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
Digital Enterprise Research Institute www.deri.ie
voiD schema
General metadata
Interlinking
Statistics
Digital Enterprise Research Institute www.deri.ie
General dataset metadata
Leveraging DublinCore: Dataset homepage Publisher Title and description Categorisation Licensing Technical features
Digital Enterprise Research Institute www.deri.ie
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/> .
Digital Enterprise Research Institute www.deri.ie
Access metadata
How to access the actual RDF triples: SPARQL endpoints RDF data dumps Root resources URI lookup endpoints OpenSearch description documents
Digital Enterprise Research Institute www.deri.ie
Access metadata
:exampleDS void:Dataset ; void:sparqlEndpoint <http://example.org/sparql> ; void:dataDump <http://example.org/dump1.rdf> ; void:uriLookupEndpoint <http://api.example.org/search?qt=term> .
Digital Enterprise Research Institute www.deri.ie
Structural metadata
High-level information about schema and internal structure of a dataset
Can be helpful when exploring or querying datasets Example resources Patterns for resource URIs Vocabularies Dataset partitions Statistics
Digital Enterprise Research Institute www.deri.ie
Structural metadata
:DBpedia a void:Dataset; void:exampleResource <http://dbpedia.org/resource/Berlin> .
:LiveJournal a void:Dataset; void:vocabulary <http://xmlns.com/foaf/0.1/> .
:DBpedia a void:Dataset; void:classPartition [ void:class foaf:Person; void:entities 312000; ]; void:propertyPartition [ void:property foaf:name; void:triples 312000; ]; .
Digital Enterprise Research Institute www.deri.ie
Describing linksets
Digital Enterprise Research Institute www.deri.ie
Describing linksets
:DBpedia a void:Dataset ; void:subset :DBpedia2Geonames .
:Geonames a void:Dataset .
:DBpedia2Geonames a void:Linkset ; void:target :DBpedia ; void:target :Geonames ; void:linkPredicate owl:sameAs .
Digital Enterprise Research Institute www.deri.ie
Deployment and Discovery
Digital Enterprise Research Institute www.deri.ie
Alongside a dataset
Digital Enterprise Research Institute www.deri.ie
Publishing a VoID file alongside a dataset Turtle RDFa
Discovery (well-known URI) http://yoursite/.well-known/void
Digital Enterprise Research Institute www.deri.ie
Users
Used by DBpedia, OpenLink, data.gov.uk, … 30% of LOD datasets have VoID metadata The entire LOD Cloud described in VoID:
semantic.ckan.net
Digital Enterprise Research Institute www.deri.ie
26
Applications
Digital Enterprise Research Institute www.deri.ie
Ed Summers’ LOD Graph
Digital Enterprise Research Institute www.deri.ie
28
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:
semantic.ckan.net
Recommended