This document describes VoID (Vocabulary of Interlinked Datasets), which is a metadata vocabulary for describing linked datasets and linksets between datasets. VoID allows datasets to provide information about structural metadata, access points, statistics, and interlinking between other datasets. It has been adopted by many datasets in the Linked Open Data cloud.

1. Digital Enterprise Research Institute www.deri.ie
VoID – Metadata for
RDF datasets
Richard Cyganiak, Linked Data Research Centre
Stefan.Decker@deri.org
http://www.StefanDecker.org/
Copyright 2010 Digital Enterprise Research Institute. All rights reserved.

2. Digital Enterprise Research Institute www.deri.ie
VoID
Vocabulary of Interlinked Datasets

3. W3C Interest Group note
Digital Enterprise Research Institute www.deri.ie
http://www.w3.org/TR/void/
3

4. 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?”

5. Read …
Digital Enterprise Research Institute www.deri.ie
http://esw.w3.org/TaskForces/CommunityProjects/LinkingOpenData/DataSets

6. Click …
Digital Enterprise Research Institute www.deri.ie

7. Sindice …
Digital Enterprise Research Institute www.deri.ie

8. Google …
Digital Enterprise Research Institute www.deri.ie

9. And even if we find a dataset …
Digital Enterprise Research Institute www.deri.ie

10. Standard questions
Digital Enterprise Research Institute www.deri.ie
 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?

11. Datasets
Digital Enterprise Research Institute www.deri.ie
 A dataset is a set of RDF triples that are published,
maintained or aggregated by a single provider

12. Linksets
Digital Enterprise Research Institute www.deri.ie
 An RDF link is an RDF triple whose subject and object
are described in different datasets
 A linksetis a collection of such RDF links between two
datasets

13. voiD schema
Digital Enterprise Research Institute www.deri.ie
Statistics
Interlinking
General metadata

14. General dataset metadata
Digital Enterprise Research Institute www.deri.ie
 Leveraging DublinCore:
 Dataset homepage
 Publisher
 Title and description
 Categorisation
 Licensing
 Technical features

15. General dataset metadata
Digital Enterprise Research Institute www.deri.ie

16. Access metadata
Digital Enterprise Research Institute www.deri.ie
 How to access the actual RDF triples:
 SPARQL endpoints
 RDF data dumps
 Root resources
 URI lookup endpoints
 OpenSearch description documents

17. Access metadata
Digital Enterprise Research Institute www.deri.ie

18. Structural metadata
Digital Enterprise Research Institute www.deri.ie
 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

19. Structural metadata
Digital Enterprise Research Institute www.deri.ie

20. Describing linksets
Digital Enterprise Research Institute www.deri.ie

21. Describing linksets
Digital Enterprise Research Institute www.deri.ie

22. Digital Enterprise Research Institute www.deri.ie
Deployment and Discovery

23. Alongside a dataset
Digital Enterprise Research Institute www.deri.ie

24. Digital Enterprise Research Institute www.deri.ie
 Publishing aVoIDfile alongside a dataset
 Turtle
 RDFa
 Discovery (well-known URI)
 http://yoursite/.well-known/void

25. Users
Digital Enterprise Research Institute www.deri.ie
 Used by DBpedia, OpenLink, data.gov.uk, …
 30% of LOD datasets have VoID metadata
 The entire LOD Cloud described inVoID:
 semantic.ckan.net

26. Applications
Digital Enterprise Research Institute www.deri.ie
26

27. Ed Summers’ LOD Graph
Digital Enterprise Research Institute www.deri.ie

28. Summary
Digital Enterprise Research Institute www.deri.ie
 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
28