Linked Data       Victor de BoerSlide stolen from Christophe Gueret
Why Linked Data?
Why linked data (1/2)Slide stolen from Christophe Gueret
Why linked data (2/2)Slide stolen from Christophe Gueret
``Sharable, spreadable and nerd-friendly’’                           -- Charlotte S H Jensen, kulturweb
Four rules of Linked Data1. Use URIs as names for things (Resources)2. Use HTTP URIs so that people can look up those   na...
Linked Open Data five star system                         Available on the web (whatever              ★                   ...
Linked Data Cloud Diagram
May 2007
Oct 2007
“Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/”
“Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/”
Amsterdam Museum as Linked Open Data
Use case on how to transform “raw” XML data into 5-star Linked Open Data
Europeana• “Europeana enables people to explore the digital  resources of Europes museums, libraries, archives and  audio-...
Amsterdam Museum• Formerly Amsterdam Historic Museum   – “The rich collection of works of art, objects     and archaeologi...
AM metadata                                                 <record priref="10541“ >• Adlib database XML API              ...
Back to the four rules of Linked Data1. Use URIs as names for things2. Use HTTP URIs so that people can look up   those na...
How to make cool URI’sUse HTTP://Use a namespace you controlUnique, stable and persistent• Don’t use:  – Author name, subj...
Amsterdam Museum URIs• PURL basename: http://purl.org/collections/nl/am/• Objects: Use “prirefs”, prefixed by “proxy-”   –...
Again, the rules of Linked Data1. Use URIs as names for things2. Use HTTP URIs so that people can look up   those names.3....
RDF reminderSubject           Predicate         Objectam:Rembrandt      am:hasBirthdate   “1651”                          ...
RDF conversion<record priref="19319 “ >   <date>1651</date>   <maker>Rembrandt (1606-1669)</maker>   <object.type>etsplaat...
Architecture SPARQL-app                      Browser                                                Purl.org              ...
How to access the data• PURL 303 redirect to VU semantic layer   http://purl.org/collections/nl/am/proxy-63432      http:...
text/html
text/html
application/rdf+xml@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .@prefix rdf: <http://www.w3.org/1999/02/22-rdf-s...
SPARQLhttp://semanticweb.cs.vu.nl/europeana/user/query
Again, the rules of Linked Data1. Use URIs as names for things2. Use HTTP URIs so that people can look up   those names.3....
Link to other sources                     “19319 ”           am:date         “1651”                                       ...
Amalgame alignment platform• Semi-automatic matching   – Simple automatic     techniques,   – chained together by hand• 35...
CKAN Data Hubhttp://thedatahub.org/dataset/amsterdam-museum-as-edm-lod
Four rules and Five stars1. Use URIs as names for   things2. Use HTTP URIs so that   people can look up those   names.3. W...
And now applications!…right??
Developers still do this…                            …although more                             and more of this          ...
Some issues with L(O)D• Extra burden on the data provider• Nerd-only (aka “SPARQL is hard”)• How do we build user-friendly...
end
EDM
What kind of RDF?• Europeana Data Model (EDM)  – Keep original metadata intact  – Use sem web (LD) principles: RDF• Re-use...
EDM voorbeeld               Provenance                  +web              views/plaatjes                                  ...
Linked data: Four rules and five stars for the Amsterdam Museum
Linked data: Four rules and five stars for the Amsterdam Museum
Linked data: Four rules and five stars for the Amsterdam Museum
Linked data: Four rules and five stars for the Amsterdam Museum
Linked data: Four rules and five stars for the Amsterdam Museum
Linked data: Four rules and five stars for the Amsterdam Museum
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Linked data: Four rules and five stars for the Amsterdam Museum

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Slides used for a guest lecture about Linked Data for the course "Knowledge and Media" at the VU Amsterdam (Nov 2011).
The talk takes the practical example of converting Amsterdam Museum data to Five-star Linked Open Data.

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  • Things = “resources”
  • - Not completely straightforward xml (nestedness)
  • XMLRDF tool: clean up, link to resources etc.
  • PREFIX am: &lt;http://purl.org/collections/nl/am/&gt;PREFIX skos: &lt;http://www.w3.org/2004/02/skos/core#&gt;SELECT ?proxy ?xWHERE {?proxy am:material ?x. ?x skos:prefLabel &quot;gietijzer&quot;@nl}ORDER BY ?proxyLIMIT 50
  • Apps for AmsterdamPlaatsen van Betekenis
  • Apps for AmsterdamPlaatsen van Betekenis
  • Apps for AmsterdamPlaatsen van Betekenis
  • Linked data: Four rules and five stars for the Amsterdam Museum

    1. 1. Linked Data Victor de BoerSlide stolen from Christophe Gueret
    2. 2. Why Linked Data?
    3. 3. Why linked data (1/2)Slide stolen from Christophe Gueret
    4. 4. Why linked data (2/2)Slide stolen from Christophe Gueret
    5. 5. ``Sharable, spreadable and nerd-friendly’’ -- Charlotte S H Jensen, kulturweb
    6. 6. Four rules of Linked Data1. Use URIs as names for things (Resources)2. Use HTTP URIs so that people can look up those names. (Dereferencing)3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things. http://www.w3.org/DesignIssues/LinkedData.html
    7. 7. Linked Open Data five star system Available on the web (whatever ★ format), but with an open license Available as machine-readable ★★ structured data (e.g. excel instead of image scan of a table) as (2) plus non-proprietary format ★★★ (e.g. CSV instead of excel) All the above plus, Use open standards from W3C (RDF and ★★★★ SPARQL) to identify things, so that people can point at your stuff All the above, plus: Link your data ★★★★★ to other people’s data to provide context www.w3.org/designissues/linkeddata.html
    8. 8. Linked Data Cloud Diagram
    9. 9. May 2007
    10. 10. Oct 2007
    11. 11. “Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/”
    12. 12. “Linking Open Data cloud diagram, by Richard Cyganiak and Anja Jentzsch. http://lod-cloud.net/”
    13. 13. Amsterdam Museum as Linked Open Data
    14. 14. Use case on how to transform “raw” XML data into 5-star Linked Open Data
    15. 15. Europeana• “Europeana enables people to explore the digital resources of Europes museums, libraries, archives and audio-visual collections.’’ www.europeana.eu From portal… …to data aggregator.
    16. 16. Amsterdam Museum• Formerly Amsterdam Historic Museum – “The rich collection of works of art, objects and archaeological finds brings to life the fortunes of Amsterdammers of days gone by and today.”• In March 2010 published their whole collection online – 70.000 objects – CC license• We converted their data to RDF
    17. 17. AM metadata <record priref="10541“ >• Adlib database XML API <acquisition.date>1997</acquisition.date> <dimension> <dimension.type>hoogte</dimension.type> <dimension.unit>cm</dimension.unit> <dimension.value>6</dimension.value>• Object metadata … </dimension> • 73.000 objects, 256MB </record> • Nested XML• Concept Thesaurus <record priref="28024“ > <term>Kalverstraat 124</term> <broader_term>Kalverstraat</broader_term> • 27.000, 9MB <term.type>GEOKEYW </term.type> • Different types (geo,motif, event) </record>• Person ‘Thesaurus’ <record priref="6" > • 67.000 persons, 10MB <biography>boekverkoper en uitgever van cartografie</biography> • Consolidated from object metadata fields <birth.date.start>1659</birth.date.start> • Creators, annotators, reproduction <death.date.start>1733</death.date.start> <name>Aa, Pieter van der</name> creators, institutions, <nationality>Nederlands</nationality> <use>Aa, Pieter van der (I)</use> </record>
    18. 18. Back to the four rules of Linked Data1. Use URIs as names for things2. Use HTTP URIs so that people can look up those names.3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things. http://www.w3.org/DesignIssues/LinkedData.html
    19. 19. How to make cool URI’sUse HTTP://Use a namespace you controlUnique, stable and persistent• Don’t use: – Author name, subject, status, access, file name extension, software mechanism C://MyDisk/awesome/VdeBoer/latest/cgi_bin/rembrandt.html
    20. 20. Amsterdam Museum URIs• PURL basename: http://purl.org/collections/nl/am/• Objects: Use “prirefs”, prefixed by “proxy-” – http://purl.org/collections/nl/am/proxy-63432• Concepts & Persons: Use “prirefs”, prefixed by “p-”, or “t-” – http://purl.org/collections/nl/am/p-201• Properties (schema): Use XML element name – http://purl.org/collections/nl/am/acquisition.date
    21. 21. Again, the rules of Linked Data1. Use URIs as names for things2. Use HTTP URIs so that people can look up those names.3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things. http://www.w3.org/DesignIssues/LinkedData.html
    22. 22. RDF reminderSubject Predicate Objectam:Rembrandt am:hasBirthdate “1651” Triplesam:Rembrandt foaf:knows am:PiterLastmanam:PiterLastman am:wasBornIn geonames:Amsterdam “1651” geonames:Amsterdam am:Rembrandt Graph am:PiterLastman
    23. 23. RDF conversion<record priref="19319 “ > <date>1651</date> <maker>Rembrandt (1606-1669)</maker> <object.type>etsplaat</object.type> priref “19319 ”… date</record> “1651” am:Record _:bn1 “Rembrandt (1606-1669)” object.type “etsplaat” “19319 ” am:date “1651” “1234” am:priref am:Record am:birthdate am:maker am:Person am:proxy-19319 “1606” am:p-1234 rda:name “Rembrandt” skos:Concept am:etsplaat “etsplaat” skos:prefLabel
    24. 24. Architecture SPARQL-app Browser Purl.org redirect SPARQL Web interface HTTP serverRDF(s) storage Logic Prolog http://semanticweb.cs.vu.nl/
    25. 25. How to access the data• PURL 303 redirect to VU semantic layer http://purl.org/collections/nl/am/proxy-63432  http://semanticweb.cs.vu.nl/europeana/browse/list_resource?r=h ttp://purl.org/collections/nl/am/proxy-63432• At our server: content negotiation – HTTP request text/html: • Local condensed view • Local full view – HTTP request application/rdf+xml • rdf/xml “describe”• SPARQL endpoint
    26. 26. text/html
    27. 27. text/html
    28. 28. application/rdf+xml@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .@prefix ore: <http://www.openarchives.org/ore/terms/> .@prefix ens: <http://www.europeana.eu/schemas/edm/> .@prefix ahm: <http://purl.org/collections/nl/am/>ahm:proxy-66970 a ore:Proxy ; ahm:title "Zegelstempel Felix Meritis"@nl ; ahm:material ahm:t-12463 , ahm:t-5447 ; ahm:objectCategory ahm:t-5504 ; ahm:objectName ahm:t-13817 , ahm:t-8489 ; ahm:objectNumber "KA 7653.1" ; ahm:priref "66970" .ahm:proxy-66972 a ore:Proxy ; ahm:acquisitionDate "0000" ; ahm:title "Zegelstempel mogelijk van familiewapen"@nl .
    29. 29. SPARQLhttp://semanticweb.cs.vu.nl/europeana/user/query
    30. 30. Again, the rules of Linked Data1. Use URIs as names for things2. Use HTTP URIs so that people can look up those names.3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things. http://www.w3.org/DesignIssues/LinkedData.html
    31. 31. Link to other sources “19319 ” am:date “1651” “1234” am:priref am:Record am:birthdate am:maker am:Personam:proxy-19319 “1606” am:p-1234 rda:name “Rembrandt” owl:sameAs (?) Viaf:nationality Viaf:Person “Dutch” Viaf:RebrandtvanRijn “Rembrandt Harmensz. rdfs:label Van Rijn”
    32. 32. Amalgame alignment platform• Semi-automatic matching – Simple automatic techniques, – chained together by hand• 3500+ links put in RDF – 143 places linked to GeoNames – 1076 persons linked to ULAN (VIAF) – 34 persons linked to DBPedia – 2498 concepts AATNed.
    33. 33. CKAN Data Hubhttp://thedatahub.org/dataset/amsterdam-museum-as-edm-lod
    34. 34. Four rules and Five stars1. Use URIs as names for things2. Use HTTP URIs so that people can look up those names.3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL)4. Include links to other URIs. so that they can discover more things.
    35. 35. And now applications!…right??
    36. 36. Developers still do this… …although more and more of this is happening
    37. 37. Some issues with L(O)D• Extra burden on the data provider• Nerd-only (aka “SPARQL is hard”)• How do we build user-friendly systems? – Ranking, user-friendly information presentation• Scalability (how do you query a huge graph?)• Licenses• Is Open always a good idea? – Context?
    38. 38. end
    39. 39. EDM
    40. 40. What kind of RDF?• Europeana Data Model (EDM) – Keep original metadata intact – Use sem web (LD) principles: RDF• Re-use of standard models – Dublin Core for metadata representation • creator, date, title etc. – SKOS for vocabularies • preferredLabel, hasBroader, etc.
    41. 41. EDM voorbeeld Provenance +web views/plaatjes proxy object metadataAggregation Physical Object geen metadata

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