Harmonizing services for LOD
vocabularies: a case study
Ghislain Atemezing, Bernard Vatant,
Raphaël Troncy, Pierre-Yves Va...
Goal and Agenda
§  Goal: align services against Linked Open Vocabularies
to harmonize and manage vocabularies’ namespaces...
Prefixes lookup headache
PREFIX.CC

What <wo> namespace stands for?

LOV

2013/10/22

WaSABi Workshop, ISWC - 2013, Sydney...
QNames and vocabulary namespaces
§  Usage of namespaces
Ø From XML syntax with xmlns declarations
Ø Use to identify a v...
Why if … global use of prefixes
§  Global namespaces
Ø With good practices to
recommend a prefix
Ø Have a more transpar...
Accessing vocabularies
§  Catalogs of vocabularies
Ø Hosting vocabularies with search, review or download
features
Ø Cu...
Existing catalogs of vocabularies

Many overlapped of vocabularies among different catalogs
2013/10/22

WaSABi Workshop, I...
LOV in a Nutshell : http://lov.okfn.org/dataset/lov/
§  A curated list of vocabularies
Ø More than 360 vocabularies
Ø E...
LOV DESCRIPTION
CORE FEATURES OF THE FRAMEWORK	
  
Domain	
  

Intended Use	
  

General	
  

Promote and
facilitate the
r...
Prefix.cc in a Nutshell: http://prefix.cc
§  A service to look up vocabularies
Ø More than 1200 namespaces registered
Ø...
LOV versus PREFIX.CC

Continuously growth of namespaces registered in prefix.cc.
Clearly view of the results of the harmon...
Aligning LOV with Prefix.cc (1)
§  Scenarios
Ø Conflicts between prefix.cc and LOV
Ø Prefixes in LOV not present in pre...
Aligning LOV with Prefix.cc (2)
§  Dealing with conflicts
Ø Clashes: same prefix but different URIs
Ø Disagreements on ...
Vocabularies leading to contact editors
§  Contacting editors/maintainers
Ø Via social platforms: LinkedIn, Google+, Twi...
Finding Vocabularies in Prefix.cc
§  LOV check API: http://lov.okfn.org/dataset/lov/apidoc/
Ø Find out namespaces in Pre...
Some Results
Category

lov-­‐able	
  vocabs	
  
Intersect-­‐prefixes	
  
vocabs	
  in	
  LOV	
  
vocabs	
  in	
  prefix.cc	
...
Conclusion and Future Work
§  We have presented a way to manage prefixes
Ø By analyzing vocabularies in LOV and prefix.c...
Thanks for your attention!

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Harmonizing services for LOD vocabularies: a case study

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This presentation describes a solution on how to align well-know services with the aim of managing and harmonizing vocabularies' metadata, with a special use case on prefix.cc.

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Harmonizing services for LOD vocabularies: a case study

  1. 1. Harmonizing services for LOD vocabularies: a case study Ghislain Atemezing, Bernard Vatant, Raphaël Troncy, Pierre-Yves Vanderbussche
  2. 2. Goal and Agenda §  Goal: align services against Linked Open Vocabularies to harmonize and manage vocabularies’ namespaces §  Motivation Ø Identify vocabularies using namespace Ø Catalogs of vocabularies §  Services managing vocabularies Ø Prefix.cc versus LOV Ø Different policies but same goal §  Aligning LOV with Prefix.cc §  Towards governance of vocabularies 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -2
  3. 3. Prefixes lookup headache PREFIX.CC What <wo> namespace stands for? LOV 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -3
  4. 4. QNames and vocabulary namespaces §  Usage of namespaces Ø From XML syntax with xmlns declarations Ø Use to identify a valid namespace §  On the Semantic Web Ø Extended notion of namespace for other RDF serialization (N3, Turtle) Ø Some de facto prefixes emerging: rdfs:, foaf:, rdf: owl: Ø SPARQL endpoints use a list of built-in prefixes not transparent to the developers 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -4
  5. 5. Why if … global use of prefixes §  Global namespaces Ø With good practices to recommend a prefix Ø Have a more transparent list of built-in prefixes Ø All the services understand each other with prefixes 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -5
  6. 6. Accessing vocabularies §  Catalogs of vocabularies Ø Hosting vocabularies with search, review or download features Ø Curated manually or semi-automatically §  Services Ø Help finding vocabularies or detect namespaces Ø Look up services: Prefix.cc, vocab.cc Ø Triple-Checker, YASGUI 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -6
  7. 7. Existing catalogs of vocabularies Many overlapped of vocabularies among different catalogs 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -7
  8. 8. LOV in a Nutshell : http://lov.okfn.org/dataset/lov/ §  A curated list of vocabularies Ø More than 360 vocabularies Ø Each of them described by vocabulary-of-a-friend (voaf) Ø Provide a dump in .n3 of the different versions of a vocabulary §  Some related services Ø  SPARQL endpoint: http://lov.okfn.org/endpoint/lov Ø  Search function: http://lov.okfn.org/dataset/lov/search Ø  An Aggregator endpoint: http://lov.okfn.org/endpoint/lov_aggregator Ø  An intelligent bot agent for updates: http://lov.okfn.org/dataset/lov/bot 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -8
  9. 9. LOV DESCRIPTION CORE FEATURES OF THE FRAMEWORK   Domain   Intended Use   General   Promote and facilitate the reuse of vocabularies in the linked data ecosystem.   Collection   Submitted by any user via LOVSuggest tool.   Gatekeeping   Manual curation and automatic URI validation   Number of Ontologies   370   Dynamics   Growing   Search metadata   Search within ontology   Yes, with visual depiction   Yes   Search across ontologies   Navigation criteria   Keyword-based; structured search (querybased)   Ordered by prefix, namespace, title and visual links navigation   CORE FEATURES OF THE FRAMEWORK   Metrics   Comments and review   Ranking   Reuse popularity on the LOD Cloud   N/A - Only by the curators   Metricbased   Web service access   SPARQL endpoint   Content available   Read/ Write   Ontology directory   Ontology registry   API   Yes   Ontology metadata , URI   Read   Yes   Yes   Applicatio   n platform   Yes   LOV DESCRIPTION WITH THE FRAMEWORK OF [d’Aquin-Noy2012-Survey] 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney -9  
  10. 10. Prefix.cc in a Nutshell: http://prefix.cc §  A service to look up vocabularies Ø More than 1200 namespaces registered Ø Anyone can add prefixes Ø In case of conflicts, users can vote §  Some related services Ø Namespace lookup API: http://prefix.cc/about/api Ø Reverse lookup API: http://prefix.cc/reverse 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 10
  11. 11. LOV versus PREFIX.CC Continuously growth of namespaces registered in prefix.cc. Clearly view of the results of the harmonization process started in March, 2013 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 11
  12. 12. Aligning LOV with Prefix.cc (1) §  Scenarios Ø Conflicts between prefix.cc and LOV Ø Prefixes in LOV not present in prefix.cc Ø URIs in prefix.cc that are actually LOV-able vocabularies §  Method Ø Federated query in SPARQL 1.1 Ø Jena ARQ command line 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 12
  13. 13. Aligning LOV with Prefix.cc (2) §  Dealing with conflicts Ø Clashes: same prefix but different URIs Ø Disagreements on preferred namespace §  Actions in case of disagreement Ø Generally 4 types of actions Ø  Important: social aspect to contact the editors of the vocabularies 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 13
  14. 14. Vocabularies leading to contact editors §  Contacting editors/maintainers Ø Via social platforms: LinkedIn, Google+, Twitter, email Ø Data retrieved mainly from vocabulary metadata. 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 14
  15. 15. Finding Vocabularies in Prefix.cc §  LOV check API: http://lov.okfn.org/dataset/lov/apidoc/ Ø Find out namespaces in Prefix.cc that are vocabularies Ø Extract them as candidate vocabularies for LOV 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 15
  16. 16. Some Results Category lov-­‐able  vocabs   Intersect-­‐prefixes   vocabs  in  LOV   vocabs  in  prefix.cc   Number 227   188   321   925   Findings  during  alignment  process   More than 200 prefixes are vocabularies 14%   lov-­‐able  vocabs   11%   Intersect-­‐prefixes   vocabs  in  LOV   56%   19%   2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney vocabs  in  prefix.cc   - 16
  17. 17. Conclusion and Future Work §  We have presented a way to manage prefixes Ø By analyzing vocabularies in LOV and prefix.cc Ø By providing mechanism of aligning two services dealing with vocabulary prefixes §  Future work Ø Provide a unique interface for submission of namespaces and prefixes to both services Ø Publish a list of common recommended prefixes Ø Foster and support current effort towards a more sustainable governance of vocabularies. 2013/10/22 WaSABi Workshop, ISWC - 2013, Sydney - 17
  18. 18. Thanks for your attention! Q/A Session
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