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Linked Data Technology and Status


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Linked Data Technology and Status

  1. Linked Data Technology & Status Dr. Myungjin LeeLinked Data & Semantic Web Technology
  2. The Semantic Web more vocabulary for describing properties and classes a vocabulary for describing properties and classes to exchange rules of RDF-based resources between many "rules languages" a protocol and query language for semantic web data sources an elemental syntax for content structure within documents a simple language for expressing data models,which refer to objects ("resources") and their relationships a string of characters used to identify a name or a resource Linked Data & Semantic Web Technology
  3. What is Linked Data? Linked data describes a method of publishing structured data so that it can be interlinked and become more useful. The Semantic Web isnt just about putting data on the web. It is about making links, so that a person or machine can explore the web of data. With linked data, when you have some of it, you can find other, related, data. - A roadmap to the Semantic Web by Tim Berners-LeeLinked Data & Semantic Web Technology
  4. Four Principles of Linked Data 1. Use URIs to identify things. 2. Use HTTP URIs so that these things can be referred to and looked up ("dereferenced") by people and user agents. 3. Provide useful information about the thing when its URI is dereferenced, using standard formats such as RDF/XML. 4. Include links to other, related URIs in the exposed data to improve discovery of other related information on the Web.Linked Data & Semantic Web Technology
  5. 5 Star Linked Data ★ Available on the web (whatever format) but with an open licence, to be Open Data ★★ 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 contextLinked Data & Semantic Web Technology
  6. The Basic Requirements for Linked Data a vocabulary for describing properties and classes of RDF-based resources a protocol and query language for semantic web data sources an elemental syntax for content structure within documents a simple language for expressing data models, which refer to objects ("resources") and their relationships a string of characters used to identify a name or a resourceLinked Data & Semantic Web Technology
  7. Linked Data & Semantic Web Technology
  8. URI, Thing, and Representation looks up URI Person refers URI links identifies and names URI Thing represents Representation <html xmlns="" xml:lang="en" lang="en"> <head> <title>Namdaemun |</title> <link rel="alternate" type="application/rdf+xml" href="" title="RDF" /> </head> <body onLoad="init();"> <div id="header"> <div> <h1 id="title">Namdaemun</h1> <div id="homelink"> &nbsp;at <a href=""></a>Linked Data & Semantic Web Technology
  9. Linked Data & Semantic Web Technology
  10. URIs for Real-World Objects • Be on the Web – Given only a URI, machines and people should be able to retrieve a description about the resource identified by the URI from the Web. • Be unambiguous – There should be no confusion between identifiers for Web documents and identifiers for other resources.Linked Data & Semantic Web Technology
  11. URIs for Real-World Objects <URI-of-alice> a foaf:Person; foaf:name "Alice"; foaf:mbox <>; foaf:homepage <> . Resource identifier (URI) ID for semantic web applications for web browsers RDF HTML RDF document URI HTML document URILinked Data & Semantic Web Technology
  12. Distinguishing between Representations and Descriptions Thing 303 redirect Generic Document application/rdf+xml content text/html negotiation RDF HTML Data & Semantic Web Technology
  13. Cool URIs • Simplicity – short and mnemonic • Stability – remain as long as possible • Manageability – issue your URIs in a way that you can manageLinked Data & Semantic Web Technology
  14. Designing URI Sets for the UK Public Sector • URIs: – name the set and describe its characteristics – identify for the real-world ‘Things’ in a single concept – provide a means of looking up data on the web – provide mechanisms to: • lookup an Identifier URI and be redirected to its Document URI • discover and get each of the Representation URIs URI Type URI structure Examples Identifier http://{domain}/id/{concept}/{reference} Data & Semantic Web Technology
  15. URI Design Principles:Creating Unique URIs for Government Linked Data • URI Template: http:// BASE / id / ORG / CATEGORY ( / TOKEN )+ • States and Territories – Owner • federal – Suggested • http://BASE/id/us/state/NAME – Example • Data & Semantic Web Technology
  16. XML (Extensible Markup Language) • a textual data format for the representation of arbitrary data structures over the Internet • both human-readable and machine-readable <title> W3C Demonstrates … title title </title> <date> date date 12 February 2013 </date> body <body> body W3C invites media, analysts, and other attendees of Mobile World Congress bold1 bold1 … bold2 </body> bold2 Concept Content Structure Presentation Related XML DTD XSLT Recommendations XML Schema XSL-fo XPathLinked Data & Semantic Web Technology
  17. Data Representation of XML • Various ways to represent data using XML – Myungjin Lee is Hye-jin’s husband. <conjugalrelation> <husband>Myungjin Lee</husband> <wife>Hye-jin Han</wife> </conjugalrelation> <conjugalrelation husband=“Myungjin Lee”> <wife>Hye-jin Han</wife> </conjugalrelation> <conjugalrelation husband=“Myungjin Lee” wife=“Hye-jin Han” /> • We need a method to represent data on abstract level.Linked Data & Semantic Web Technology
  18. RDF (Resource Description Framework) • a general method for conceptual description or modeling of information that is implemented in web resources, using a variety of syntax formats – Myungjin Lee is Hye-jin’s husband. hasWifeLinked Data & Semantic Web Technology
  19. Data Representation of RDF hasWife Subject Predicate Object URI reference URI reference URI reference or Literal TripleLinked Data & Semantic Web Technology
  20. RDF Example 4 115” Data & Semantic Web Technology
  21. RDF Serialization • N-Triples – RDF Test Cases, W3C Recommendation, 10 February 2004 – a line-based, plain text serialization format for storing and transmitting RDF data • Notation 3 (N3) – a shorthand non-XML serialization of RDF models, designed with human- readability in mind – much more compact and readable than XML RDF notation • Turtle (Terse RDF Triple Language) – W3C Candidate Recommendation, 19 February 2013 – a format for expressing data in the Resource Description Framework (RDF) data model – a subset of Notation3 (N3) language, and a superset of the minimal N- Triples format • RDF/XML – W3C Recommendation, 10 February 2004 – an XML syntax for writing down and exchanging RDF graphs Data & Semantic Web Technology
  22. N-Triple<> <> "Tony Benn" .<> <> "Wikipedia" . N3 @prefix dc: <>. <> dc:title "Tony Benn"; dc:publisher "Wikipedia". RDF/XML <rdf:RDF xmlns:rdf="" xmlns:dc=""> <rdf:Description rdf:about=""> <dc:title>Tony Benn</dc:title> <dc:publisher>Wikipedia</dc:publisher> </rdf:Description> </rdf:RDF> Turtle @prefix rdf: <> . @prefix dc: <> . @prefix ex: <> . <> dc:title "RDF/XML Syntax Specification (Revised)" ; ex:editor [ ex:fullname "Dave Beckett"; ex:homePage <> ] .Linked Data & Semantic Web Technology
  23. Linked Data & Semantic Web Technology
  24. RDF 1.0 vs RDF 1.1 RDF 1.0 RDF 1.1 IRI (Internationalized Resource Identification URI Resource Identifier) Multiple RDF Graphs X O HTML content for literal X rdf:HTML valueLinked Data & Semantic Web Technology
  25. Recommendations of RDFLinked Data & Semantic Web Technology
  26. RDF Schema • W3C Recommendation, 10 February 2004 • to define classes and properties that may be used to describe classes, properties and other resources • RDF Schema allows – Definition of Classes – Definition of Properties and Restrictions – Definition of HierarchiesLinked Data & Semantic Web Technology
  27. RDF Schema ExampleTBox - terminological component rdf:type car:Vehicle rdf:Property rdfs:Class rdfs:subClassOf rdf:type rdf:type car:Car car:body_style rdfs:domain rdf:type rdfs:range car:A6 car:Sedan car:Style car:body_style rdf:typeABox - assertion component Linked Data & Semantic Web Technology
  28. RDF Semantics • to provide a formal meaning based on a model- theoretic semantics in its abstract syntax <x, y> is in IEXT(I(rdfs:subClassOf)) if and only if x and y are in IC car:Vehicle and ICEXT(x) is a subset of ICEXT(y) rdfs:subClassOf car:Car rdf:type rdf:type car:A6Linked Data & Semantic Web Technology
  29. SPARQL • Why do we need a query language for RDF? – Why de we need a query language for RDB? – to get to the knowledge from RDF • SPARQL Protocol and RDF Query Language – to retrieve and manipulate data stored in Resource Description Framework format – to use SPARQL via HTTPLinked Data & Semantic Web Technology
  30. SPARQL Example PREFIX foaf: <> SELECT ?name ?email WHERE { ?person a foaf:Person. ?person foaf:name ?name. ?person foaf:mbox ?email. } RDF Knowledge Base ?name ?email Myungjin Lee Gildong Hong Grace Byun grace@naver.comLinked Data & Semantic Web Technology
  31. SPARQL Query Forms • SELECT query – Used to extract raw values from a SPARQL endpoint, the results are returned in a table format. • CONSTRUCT query – Used to extract information from the SPARQL endpoint and transform the results into valid RDF. • ASK query – Used to provide a simple True/False result for a query on a SPARQL endpoint. • DESCRIBE query – Used to extract an RDF graph from the SPARQL endpoint, the contents of which is left to the endpoint to decide based on what the maintainer deems as useful information.Linked Data & Semantic Web Technology
  32. OWL (Web Ontology Language) • knowledge representation languages for authoring ontologies • If you need more expressiveness  OWL – such as, Man ∩ Woman =Ø descendant descendant Person Person Person Genre descendant type hasGenre _01 Action 1:1 Husband Wife subClassOf ActionMovieLinked Data & Semantic Web Technology
  33. What more do we need? SPARQL Linked Data Platform Linked Data Service RDFa HTML + RDBMS Triple Store HTML HTML RDF Knowledge R2RML GRDDLLinked Data & Semantic Web Technology
  34. • RDB to RDF Mapping Language • W3C Recommendation 27 September 2012 • a language for expressing customized mappings from relational databases to RDF datasets RDB R2RML @prefix rr: <>. @prefix ex: <>. <#TriplesMap1> rr:logicalTable [ rr:tableName "EMP" ]; rr:subjectMap [ rr:template "{EMPNO}"; rr:class ex:Employee; ]; rr:predicateObjectMap [ rr:predicate ex:name; rr:objectMap [ rr:column "ENAME" ]; ]. Result <> rdf:type ex:Employee. <> ex:name "SMITH".Linked Data & Semantic Web Technology
  35. Linked Data Platform • A set of best practices and simple approach for a read-write Linked Data architecture, based on HTTP access to web resources that describe their state using RDF • W3C Working Draft 25 October 2012Linked Data & Semantic Web Technology
  36. RDFa (the Resource Description Framework in attributes) • W3C Recommendation, 07 June 2012 • to express machine-readable data in Web documents like HTML, SVG, and XML Example<p vocab="" resource="#manu" typeof="Person"> My name is <span property="name">Manu Sporny</span> and you can give me a ring via <span property="telephone">1-800-555-0199</span>. <img property="image" src="" /> </p>Linked Data & Semantic Web Technology
  37. (Gleaning Resource Descriptions from Dialects of Languages) • a mechanism and markup format for Gleaning Resource Descriptions from Dialects of Languages to obtain RDF triples out of XML documents, including XHTMLHTML <html xmlns:grddl= grddl:transformation="glean_title.xsl getAuthor.xsl"> <head> <title>Are You Experienced?</title> </head> ... glean_title.xsl <xsl:stylesheet version="1.0"> <xsl:template match="/"> <rdf:RDF xmlns:rdf=""> <rdf:Description rdf:about="{$subject}"> <dc:title> <xsl:value-of select="/html:html/html:head/html:title"/> </dc:title> </rdf:Description> </rdf:RDF> </xsl:template> </xsl:stylesheet> RDF <rdf:RDF> <rdf:Description rdf:about=""> <dc:title>Are You Experienced?</dc:title> </rdf:Description> Linked Data & Semantic Web Technology </rdf:RDF>
  38. Jena Platform SPARQL Fuseki ARQ & LARQ Linked Data Service Jena API RDBMS Triple Store HTML HTML HTML TDB & SDBLinked Data & Semantic Web Technology
  39. Openlink Virtuoso • a middleware and database engine hybrid that combines the functionality of a traditional RDBMS, ORDBMS, RDF, XML, etc. – Relational Data Management – RDF Data Management – XML Data Management – Free Text Content Management & Full Text Indexing – Document Web Server – Linked Data Server – Web Application Server – Web Services Deployment (SOAP or REST)Linked Data & Semantic Web Technology
  40. Openlink Virtuoso Coverage SPARQL SPARQL Server Linked Data Service RDBMS Triple Store HTML HTML HTML Sponger Storage and InferenceLinked Data & Semantic Web Technology
  41. Linking Open Data cloud diagramLinked Data & Semantic Web Technology
  42. User Generated Content Media PublicationsGovernment Domain Number of datasets Triples (Out-)Links Media 25 18,4185,2061 5044,0705 Geographic 31 61,4553,2484 3581,2328 Government 49 133,1500,9400 1934,3519 Publications 87 29,5072,0693 1,3992,5218 Cross-domain 41 41,8463,5715 6318,3065 Life Sciences 41 30,3633,6004 1,9184,4090 User-generated Content 20 1,3412,7413 344,9143 Total 295 316,3421,3770 5,0399,8829 Geographic Life Sciences Cross-DomainLinked Data & Semantic Web Technology
  43. KDATA (Linked Data for Korea) Domain Triples 3,899 44,278 2,969 126,469 1,130 2,833 5,539 47,340 228,872 4,450 5,392 109,101 1,155 WiFi 1,671 KDATA 808 4,535 10,605 80,156 49,799 3,256 9,418 2,429 16,212 14,300 6,931 39,218 115,099 139,608 1,077,472Linked Data & Semantic Web Technology
  44. SPARQLselect ?swhere { ?s rdf:type <> . ?s rdfs:label "남대문" .} HTML <rdf:RDF> <rdf:Description rdf:about=""> <rdfs:label>RDF description of Namdaemun</rdfs:label> <foaf:primaryTopic> <kdc:StateDesignatedHeritage rdf:about=""> <rdfs:label>남대문</rdfs:label> <rdfs:label>숭례문</rdfs:label> <foaf:depiction rdf:resource="20060227132556895000.jpg"/> <owl:sameAs rdf:resource=""/> ... </rdf:RDF> RDF Linked Data & Semantic Web Technology
  45. Contents Search on the Semantic Web Dr. Myungjin Lee e-Mail : Twitter : Facebook : SlideShare :