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Madrid Building blocks of Linked Data
This document provides an overview of linked data and the semantic web. It discusses moving from a web of documents to a web of data by making data on the web more structured and interconnected. The key aspects covered include using URIs to identify things, providing structured data about those things via standards like RDF, and including links to other related data to improve discovery. The document also explains some of the core technologies involved like RDF, RDF syntaxes, vocabularies for describing data, and publishing and accessing linked data on the web.
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Madrid Building blocks of Linked Data
- 1. Linked Data Building blocks Victorde Boer With slides from Knud Hinnerk Moller, Kasper Brandt, Christophe Gueret
- 2. Web of Documents(WWW) Linked Documents
- 3. From text todata > increased semantics
- 4. More and morestructured data available online • Governments • Social web data • Medical data • Museums • Research data ? Moverum.com
- 5. Web of Documentsvs Web of Data • People are often not interested in documents, they are interested in things (information) – Humans are very good at reading (web) documents and distilling information • Computers are very good at calculating, combining and filtering information. But they are very bad at reading documents – We need to help machines understand web data – Write it down in a way that they can understand LINKED DATA!!
- 6. Web of Documents(WWW) Linked Documents
- 7.
- 8. without Slide stolen fromChristophe Gueret
- 9. with Linked Data Slidestolen from Christophe Gueret
- 10. http://info.cern.ch/Proposal.html Tim Berners-Lee (The inventorof the Web) And the Semantic Web
- 12. What is LinkedOpen Data? Intermezzo Intermezzo
- 13. Open Data is aboutlicenses to allow reuse Linked Data is about technology for interoperability Intermezzo Intermezzo
- 14. ★ Available on theweb (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 Linked Data five star system (TBL) Intermezzo Intermezzo
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- 16. Examples of LinkedData • Academia, Research • Community • Libraries, Museums, Cultural Heritage • Government and public institutions (Open Data) • Media • Business
- 18. How does allthis work? • Data, not documents • Structured data • Graph (networked) data! • W3C Web standards stack – URIs, HTTP, RDF, RDFa, RDFS, OWL, SPARQL, etc.
- 19. Four rules ofLinked Data 1. Use URIs as names for things 2. 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) 4. Include links to other URIs. so that they can discover more things. http://www.w3.org/DesignIssues/LinkedData.html
- 20. Semantic Web standardfor writing down data, information (Subject, Relation, Object) Resource Description Framework (RDF) Painting001 Amsterdam has_location Painting001 has_location Amsterdam . Painting001 title “Nachtwacht”. title “Nachtwacht”
- 21. Use HTTP URIsfor Things • Uniform Resource Identifier (URI) is a string of characters used to identify a name of a resource • http://rijksmuseum.nl/data/schilderij1 • I can go there (dereference) and then I get information about it – HTML page for humans – RDF data for machines
- 22. CURIEs • Compact URIs •replace URI up to last element with prefix • define prefix in Turtle: http://www.w3.org/TR/curie/ http://www.w3.org/2001/XMLSchema#date xsd xsd:date @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . “namespace”
- 23. Blank Nodes • Resourceswithout a URI – Might have local identifiers • Used for grouping, re-ification,… • Hard to use in Linked Data context Painting001 has_creator name “El Greco” Creator_type Painter Probability unlikely
- 24. Links • Link yourdata to other data – By establishing RDF triples that point to other people’s data – By reusing other people’s URIs
- 25. Example: Link toGeonames IDS: document 0002 Country:”Gambia” Geonames:Gambia Region: Africa population : 1593256 N 13° 30' 0'' W 15° 30' 0'
- 26. Turtle Syntax @prefix data:<http://data.example.org/> . @prefix vocab: <http://voc.example.org/> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . data:shanghai vocab:located_in data:peoples_republic_of_china ; vocab:name "Shang-hai"@ga, "Shanghai"@en, "上海"@zh ; vocab:population "23019148"^^xsd:int . data:sjtu vocab:located_in data:shanghai ; vocab:name "Shanghai Jiao Tong University"@en . define prefixes http://www.w3.org/TR/turtle/ abbreviate URIs as CURIEs group triples with same subject,predicate group triples with same subject Unicode
- 27. Other Syntaxes • RDF/XML –XML-based syntax – still widely used, but less readable than Turtle • RDFa – RDF embedded in HTML, using element attributes • JSON-LD – JSON serialisation • Named Graph Support: Trig (Turtle), Trix (RDF/XML), N-Quads (N-Triples)
- 28. Named Graphs • divideRDF graph in a dataset into several subgraphs • each subgraph labelled with a URI • useful for keeping track of provenance, timestamps, versioning, etc. • not officially part of the standard, but widely supported by tools (and by SPARQL, see tomorrow)
- 29. RDF – Summary •Graph data model for the Web • Triples (or “statements”): – <subject> <predicate> <object> – (or <thing> <relationship> <thing>) • Resources – Things about which we want to make statements – URIs (ideally HTTP URIs) • Literals: – Values like strings, numbers, dates, booleans, … – Either language tag (zh, en, …) or XML Schema datatype • Subjects and predicates are always resources • Objects can be resources or literals • Named Graphs (not standard): divide graph into subgraphs
- 30. Some Terms toDefine Terms (RDF(S)) • rdf:type (or just a in Turtle) – special property to say what kind of a thing ("class") a resource is • rdfs:label, rdfs:comment – documentation for humans • rdfs:Class, owl:Class – this term is a class • rdfs:Property, owl:DatatypeProperty, owl:ObjectProperty – this term is a property, special kind of property
- 31. Some Terms toDefine Terms (RDF(S)) • rdfs:subClassOf – defining class hierarchies • rdfs:subPropertyOf – defining property hierarchies • rdfs:definedBy – where is this term defined, where can I get the specification?
- 32. Reuse things: Vocabularies •FOAF (Friend of a Friend): People, Organisations, Social Networks • Dublin Core (Bibliographic): publications, authors, media, etc. • schema.org (Google, Yahoo!, Bing, Yandex): cross- domain, what search engines are interested in (people, events, products, locations) • Good Relations: business, products, etc. rijks:Painting001 Amsterdam http://purl.org/dc/terms/spatial
- 33. Reuse things: Datasets •GeoNames: Geographical data • DBPedia: RDF version of Wikipedia (also in Dutch) • GTAA: (Gemeenschappelijke Thesaurus Audiovisuele Archieven): Persons, topics, AV- terms • VIAF: Persons rijks:Painting001 http: //sws.geonames.org/2759794/ http://purl.org/dc/terms/spatial
- 35.
- 36. Four rules ofLinked Data 1. Use URIs to identify things (Resources). 2. Use HTTP URIs so that these things can be referred to and looked up ("dereference") by people and user agents 3. Provide useful information (i.e., a structured description - metadata) about the thing when its URI is dereferenced. 4. Include links to other, related URIs in the exposed data to improve discovery of other related information on the Web. www.w3.org/DesignIssues/LinkedData.html
- 37. So that meansthat When I ask for a URI dbpedia:Amsterdam I want some data back, describing that resource
- 38. Content negotiation Reply basedon preference expressed in HTTP request response header (Accept:) GET /resource/Amsterdam HTTP/1.1 Host: dbpedia.org Accept: text/html;q=0.5, application/rdf+xml I’m ok with HTML… …but I really prefer RDF
- 39. text/html body onload="init();" about="dbpedia:Amsterdam"> <divid="header"> <div id="hd_l"> <h1 id="title">About: <a href="dbpedia:Amsterdam">Amsterdam</a></h1> <div id="homelink"> <!--?vsp if (white_page = 0) http (txt); ?--> </div> <div class="page-resource-uri"> An Entity of Type : <a href="http://dbpedia.org/ontology/City">city</a>, from Named Graph : <a href="http://dbpedia.org">http://dbpedia.org</a>, within Data Space : <a href="http://dbpedia.org">dbpedia.org</a> </div> </div> <!-- hd_l --> <div id="hd_r"> <a href="http://wiki.dbpedia.org/Imprint" title="About DBpedia"> <img src="/statics/dbpedia_logo.png" height="64" alt="About DBpedia"/> </a> </div> <!-- hd_r --> </div> <!-- header --> <div id="content"> <p>Amsterdam is de hoofdstad en grootste gemeente van Nederland. De stad, in het Amsterdams ook Mokum genoemd, ligt in de provincie Noord-Holland, aan de monding van de Amstel en aan het IJ. De naam van de stad komt van de ligging bij een in de 13e eeuw aangelegde dam in de Amstel. De plaats kreeg stadsrechten rond 1300 en groeide tot één van de grootste handelssteden ter wereld in de Gouden Eeuw.</p>
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- 41. application/rdf+xml <rdf:Description rdf:about="dbpedia:Amsterdam"> <rdf:type rdf:resource="http://schema.org/City"/> <rdf:type rdf:resource="http://dbpedia.org/ontology/City" /> <rdf:type rdf:resource= "http://dbpedia.org/class/yago/GeoclassCapitalOfAPoliticalEntity" /> <rdf:type rdf:resource="http://dbpedia.org/ontology/Place" /> <rdf:type rdf:resource="http://dbpedia.org/class/yago/CitiesInTheNetherlands" /> <rdf:type rdf:resource="http://dbpedia.org/class/yago/PortCitiesAndTownsInTheNet herlands" /> <rdf:type rdf:resource= "http://dbpedia.org/class/yago/PortCitiesAndTownsOfTheNorthSea" /> <rdf:type rdf:resource= "http://umbel.org/umbel/rc/Location_Underspecified" /> <rdf:type rdf:resource="http://dbpedia.org/ontology/Settlement" /> …
- 42. application/x-turtle <dbpedia:Amsterdam> <dbprop:/subdivisionName> "Amsterdam"@en. <dbprop:/aprSun> "183"^^<http://www.w3.org/2001/XMLSchema#int> . <http://www.w3.org/2000/01/rdf-schema#comment> "Amsterdam u2013 najwiu0119ksze miasto Holandii i jej stolica konstytucyjna. Wszystkie instytucje rzu0105dowe …."@pl . <http://dbpedia.org/ontology/timeZone> <dbpedia:Central_European_Summer_Time> . <http://xmlns.com/foaf/0.1/name> "Amsterdam"@en . <http://www.georss.org/georss/point> "52.37305555555555 4.892222222222222"@en . <dbprop:/yearSun> "1662"^^<http://www.w3.org/2001/XMLSchema#int> . <http://dbpedia.org/ontology/leaderTitle> "Secretary"@en . ….
- 43. What actually shouldhappen GET /resource/Amsterdam HTTP/1.1 Host: dbpedia.org Accept: text/html;q=0.5, application/rdf+xml HTTP/1.1 303 See Other Location: http://dbpedia.org/data/Amsterdam Vary: AcceptGET /data/Amsterdam HTTP/1.1 Host: dbpedia.org Accept: text/html;q=0.5, application/rdf+xml HTTP/1.1 200 OK Content-Type: application/rdf+xml;charset=utf-8 <?xml version="1.0"?> <rdf:RDF xmlns:units="http://dbpedia.org/units/" xmlns:foaf="http://xmlns.com/foaf/0.1/" xmlns:geon="http://www.geonames.org/ontology#" xmlns:rdfs="http://www.w3.org/2000/01/rdf- schema#"
- 44. Which part ofthe graph? Concise bounded description This notion is also known as "the bnode- closure of a resource“ Symmetric Concise bounded description is similar to cbd, but includes triples with both URI as subject and object. Dereferenced URI Dereferenced URI
- 45. Recipes for publishingLinked Data 1. Serving Linked Data as Static RDF/XML Files 2. Serving Linked Data as RDF Embedded in HTML Files 3. Serving RDF and HTML with Custom Server-Side Scripts 4. Serving Linked Data from Relational Databases 5. Serving Linked Data by Wrapping Existing Application or Web APIs 6. Serving Linked Data from RDF Triple Stores Tom Heath, Chris Bizer http://linkeddatabook.com/
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- 49. Statistics: predicates ina Named Graph
- 50. Local view ofa resource
- 51. Get external RDFdata from the Linked Data Cloud
- 52. Query the LinkedData cloud ClioPatria allows you to dereference external links and load the RDF that is referenced in a separate named graph The data is only “Linked” if it contains references to resources outside of your domain. – Reuse Properties and Classes from ontologies such as RDF(S), SKOS, OWL – Link to outside resources (DBPedia, GeoNames,…)
- 53. SPARQL endpoint andweb interface
- 54. Serving Linked Data •LOD module in ClioPatria – Server responds with description of requested resource – Content negotiation • HTML when text/html • RDF/XML, JSON, Turtle when appropriate Accept – Return either Concise Bounded Description or Symmetric Concise Bounded description
- 55. PURL.ORG URIs PURL.org isa service that allows you to redirect URIs to another server. In this case, we do a partial redirect to our prefixed server From http://purl.org /collections/example/ to http://eculture.cs.vu.nl:1234/example/lod/collections/example/
- 56.
- 57. Example: Dutch Shipsand Sailors
- 58. KB Delpher Dutch-Asiatic Shipping(DAS) – Voyages (Huygens ING) “VOC Opvarenden” Mustering and payroll information (DANS Easy) Dutch Ships and Sailors
- 59.
- 60. Modeling in collaborationwith historians (1) dss:Record mdb:Aanmonstering mdb:aanmonstering-del_gem-1879- 101 dss:Record mdb:PersoonsContract mdb:persoonscontract- del_gem-1879-101-16858- Pieter_Hoekstra dss:Schip mdb:Schip mdb:schip-del_gem-1879-101-Isadora dss:ship mdb:ship “1870-1894" "Isadora " rdfs:label dss:shipname mdb:scheepsnaam dss:ShipType mdb:ScheepsTy pe mdb:schoener dss:shiptype mdb:scheepstype “32” dcterms:identifier mdb:inventarisnummer mdb:has_KB_article <http://resolver.kb.nl/resolve?urn =ddd:010063756:mpeg21:a0045:oc r> mdb:schip-del_gem-1879-137- Isadora owl:sameAs dss:has_aanmonstering mdb:has_person foaf:Person dss:Person mdb:Person mdb:persoon-del_gem-1879-101-16858 dss:ran k mdb:ra nk dss:Rank mdb:Rang mdb:matroos mdb:maandgage “Pieter" foaf:firstname mdb:voornaa m “Hoekstr a" foaf:lastname mdb:achternaam Jur Leinenga (Huygens ING) Muster-rolls Northern Provinces 1803-1937
- 61. Modeling in collaborationwith historians (2) dss:Record gzmvoc:Telling gzmvoc:telling-1046- De_Berkel __bnode_ 1gzmvoc:aziatischeBemanning dss:Ship gzmvoc:Schip gzmvoc: schip-1046- De_Berkel dss:has_ship gzmvoc:schip "1046" “Schip” “De Berkel” rdfs:label dss:scheepsnaam gzmvoc:scheepsnaam dss:ShipType gzmvoc:Scheepst ype gzmvoc: type- Ship dss:has_shiptype gzmvoc:has_shiptype gzmvoc:scheepstype “21” “Moorse mattroosen ” dss:azRegistratieKop gzmvoc:azAantalMatrozen gzmvoc:telling gzmvoc:heeft DAS heenreis dss:Record das:Voyage das:voyage- 1918_61 Matthias van Rossum (VU-hist) Payroll information for European vs Asiatic Sailors (17th / 18th C)
- 62. mdb:Schip1 mdb:Kof mdb:scheepsType das:ShipX das:Kofship das:typeOfShip dss:has_shipType rdfs:subPropertyOf rdfs:subPropertyOf Linkproperties and classes to interoperability layer
- 63. mdb:Schip1 mdb:Kof mdb:scheepsType das:ShipX das:Kofship das:typeOfShip Aat:Kof Aat:Platbodems skos:exactMatch skos:exactMatch skos:exactMatch VocabularyLinks Links to DBPedia (Ship types, places, ranks) Links to Getty AAT (Ship types, ranks) Links to GeoNames (Places)
- 64. DAS (Dutch AsiaticShipping) examples http://resources.huygens.knaw.nl/retroboeken/das http://purl.org/collections/nl/dss/das/voyage-5580_1 http://purl.org/collections/nl/dss/das/voyage-5580_1.ttl http://purl.org/collections/nl/dss/das/voyage-5580_1.json http://purl.org/collections/nl/dss/das/voyage-5580_1.rdf
- 65. Thank you! Victor deBoer http://victordeboer.com [email protected]
Editor's Notes
- #2 Laura doet: - Sem tech / search - Patronen Cases modeleren en publiceren van Linked Data Modeleren van Events - Polimedia ( - E-culture) Victor doet: - Am.museum - Tools – Carmen? - Historische use cases - VK, Bioned, DSS
- #11 -interestingly, when you look at Tim Berners-Lees original proposal for the WWW from 1989, you can see that he already had some sort of Semantic Web in mind -sure, there are documents, but there are also concepts like “Computer Conferencing”, there are organisations, there are people -also, the links between all those nodes in the graph were meant to be much more expressive than just simple, untyped hyperlinks, like we have them on the WWW today
- #17 - Before we go into the details with specific technologies, we’re going to give you some example of where this type of thinking has been applied Web semantics and Linked Data started out in academia in computer science and AI research, so that’s where originally most applications could be found However, this quickly moved from there to other domains in research Then into community efforts, public institutions, cultural institutions, as well as governments and administration – areas where was probably not to make a profit Media with their vast amount of content have increasingly made use of Linked Data Businesses are also recently seeing more and more benefits from using structured, linked data, for different reasons (internal efficiency, graph data as an improvement to the product (search engines), graph data as a valuable resource)
- #18 BBC Wildlife Finder Also aggregating data from Wikipedia, etc.
- #20 Things = “resources”
- #27 -N-Triples is as close as possible to the RDF data model, and easy to parse very efficiently for machines. -however, that makes it very verbose and hard to handle for humans -The Turtle (“Terse RDF Triple Language”) Syntax is there to fix that -it’s based on N-Triples (N-Triples is a subset of Turtle): every N-Triples document is also a valid Turtle document http://www.w3.org/TR/turtle/ http://www.w3.org/TR/curie/
- #37 Images (TBL)
- #39 HTTP request response header
- #59 Monsterrollen-database 1803-1937: Monsterrollen zijn bemanningslijsten met naam, rang, gage, woonplaats en leeftijd van elke zeeman aan boord, evenals de naam, het type en de grootte van het schip. […] voor Groningen en Friesland ligt het begin pas in de negentiende eeuw. Ze gunnen ons een kijkje in het beroepsleven van de zeeman in de negentiende en begin twintigste eeuw. Matthias van Rossum onderzocht de verhoudingen tussen Europese en Aziatische zeelieden onder de Verenigde Oost-Indische Compagnie (1602-1795) erg gelijkwaardig waren. Dat is in scherp contrast met de latere 19de eeuwse situatie, toen Aziatische zeelieden in een ongelijkwaardige en soms onvrijere positie werkten onder slechtere behandeling en beloning. Het werken onder de VOC werd bovendien gekenmerkt door een nuchter multiculturalisme.