07 Linked Data Engineering - 2

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Lecture 7, Linked Data Engineering, RDF, RDFS, SPARQL

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07 Linked Data Engineering - 2

  1. 1. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 7: Linked Data Engineering - 2 Prof. Dr. Harald Sack FIZ Karlsruhe - Leibniz Institute for Information Infrastructure AIFB - Karlsruhe Institute of Technology Summer Semester 2017 This file is licensed under the Creative Commons Attribution-NonCommercial 3.0 (CC BY-NC 3.0)
  2. 2. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Last Lecture: Linked Data Engineering - 1 3.1 Knowledge Representations and Ontologies 3.2 Semantic Web and the Web of Data 3.3 Linked Data Principles 3.4 How to name Things - URIs 3.5 Resource Description Framework (RDF) 3.6 Creating new Models with RDFS 3.7 Querying RDF(S) with SPARQL 3.8 More Expressivity with Web Ontology Language (OWL) 3.9 Wikipedia, DBpedia, and Wikidata 3.10 Linked Data Programming ● Ontologies and the Semantic Web ● Semantic Web Architecture ● Linked Data Principles ● URIs and URLs ● Designator and Designatum ● The RDF Data Model
  3. 3. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 7: Linked Data Engineering - 2 3.1 Knowledge Representations and Ontologies 3.2 Semantic Web and the Web of Data 3.3 Linked Data Principles 3.4 How to name Things - URIs 3.5 Resource Description Framework (RDF) as simple Data Model 3.6 Creating new Models with RDFS 3.7 Querying RDF(S) with SPARQL 3.8 More Expressivity with Web Ontology Language (OWL) 3.9 Wikipedia, DBpedia, and Wikidata 3.10 Linked Data Programming
  4. 4. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework RDF is a Triple Model i.e. every piece of knowledge is broken down into ( subject , predicate , object ) http://www.slideshare.net/fabien_gandon RDF is a Graph Model i.e. every piece of knowledge is interpreted as ( vertex , edge , vertex )
  5. 5. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> “1930” . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/CelestialBody> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/place> . … … ... <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthdate> “1906-02-04” . <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthplace> <http://dbpedia.org/resource/Streator,_Illinois> . … … ... <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/motto> “Quiet Surprise in the Prairie” . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#lat> “41.120834”^^xsd:float . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#long> “-88.835281”^^xsd:float . … … ... Subject Property Object RDF Triples
  6. 6. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> “1930” . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/CelestialBody> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/place> . … … ... <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthdate> “1906-02-04” . <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthplace> <http://dbpedia.org/resource/Streator,_Illinois> . … … ... <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/motto> “Quiet Surprise in the Prairie” . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#lat> “41.120834”^^xsd:float . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#long> “-88.835281”^^xsd:float . … … ... Individuals (Entities)
  7. 7. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> “1930” . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/CelestialBody> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/place> . … … ... <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthdate> “1906-02-04” . <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthplace> <http://dbpedia.org/resource/Streator,_Illinois> . … … ... <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/motto> “Quiet Surprise in the Prairie” . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#lat> “41.120834”^^xsd:float . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#long> “-88.835281”^^xsd:float . … … ... Classes
  8. 8. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> “1930” . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/CelestialBody> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/place> . … … ... <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthdate> “1906-02-04” . <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthplace> <http://dbpedia.org/resource/Streator,_Illinois> . … … ... <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/motto> “Quiet Surprise in the Prairie” . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#lat> “41.120834”^^xsd:float . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#long> “-88.835281”^^xsd:float . … … ... Literals
  9. 9. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> “1930” . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/CelestialBody> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/place> . … … ... <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthdate> “1906-02-04” . <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthplace> <http://dbpedia.org/resource/Streator,_Illinois> . … … ... <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/motto> “Quiet Surprise in the Prairie” . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#lat> “41.120834”^^xsd:float . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#long> “-88.835281”^^xsd:float . … … ... Properties
  10. 10. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> “1930” . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/CelestialBody> . <http://dbpedia.org/resource/Pluto> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://schema.org/place> . … … ... <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthdate> “1906-02-04” . <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/birthplace> <http://dbpedia.org/resource/Streator,_Illinois> . … … ... <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/motto> “Quiet Surprise in the Prairie” . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#lat> “41.120834”^^xsd:float . <http://dbpedia.org/resource/Streator,_Illinois> <http://www.w3.org/2003/01/geo/wgs84_pos#long> “-88.835281”^^xsd:float . … … ... Vocabularies / Ontologies
  11. 11. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Resource Description Framework 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model ● Knowledge in RDF is expressed as a list of statements ● all RDF statements follow the same simple schema, i.e. the RDF Triple Subject Property Object / Value URI URI URI / Literal RDF Building Blocks <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> "1930" . N-Triples Serialization <http://dbpedia.org/resource/Pluto> "1930" <http://dbpedia.org/ontology/discovered> graph representation
  12. 12. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Resource Description Framework 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model ● URIs and Literals ○ URIs reference resources uniquely ○ Literals describe data values that don’t have a separate existence <http://dbpedia.org/resource/Pluto> "1930" <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> Literal Entity
  13. 13. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Literals and Datatypes 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model ● Typed literals can be expressed via XML Schema datatypes ● Namespace for typed literals: http://www.w3.org/2001/XMLSchema# ● Examples: "Semantics"^^<http://www.w3.org/2001/XMLSchema#string> "1161.00"^^<http://www.w3.org/2001/XMLSchema#float> "2015-08-02"^^<http://www.w3.org/2001/XMLSchema#date> ● Language Tags denote the (natural) language of the text: ○ Example: "Semantik"@de , "Semantics"@en http://www.w3.org/TR/2013/WD-rdf11-concepts-20130115/#xsd-datatypes
  14. 14. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Blank Nodes 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model ● Blank Nodes ○ denote existence of an individual with specific attributes, but without providing an identification or reference "1930" <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> Blank Node Cannot be referenced externally
  15. 15. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Serializations 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model ● RDF comes with several different serialization formats: ○ N-Triples, RDF/XML, JSON, Turtle, TriG, N-Quads, RDFa, ... RDF/XML N-Triples JSON-LDTurtle TriG N-Quads extended by support for multiple graphs We will use RDF/Turtle
  16. 16. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● N-Triples Notation ○ URIs/IRIs in angle brackets ○ Literals in quotation marks ○ Triple ends with a period RDF Serializations 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model <http://dbpedia.org/resource/Pluto> "1930" <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> "1930" . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> .
  17. 17. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Serializations 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model <http://dbpedia.org/resource/Pluto> "1930" <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> ● RDF/XML Notation <?xml version="1.0" encoding="utf-8" ?> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:ns0="http://dbpedia.org/ontology/"> <rdf:Description rdf:about="http://dbpedia.org/resource/Pluto"> <ns0:discovered>1930</ns0:discovered> <ns0:discoverer rdf:resource="http://dbpedia.org/resource/Clyde_Tombaugh"/> </rdf:Description> </rdf:RDF> S P O
  18. 18. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Serializations 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model <http://dbpedia.org/resource/Pluto> "1930" <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> ● JSON-LD Notation (RDF 1.1) { "@id" : "http://dbpedia.org/resource/Pluto" , "http://dbpedia.org/ontology/discovered" : { "@value" : "1930" } , "http://dbpedia.org/ontology/discoverer" : { "@id" : "http://dbpedia.org/resource/Clyde_Tombaugh"} } S P O
  19. 19. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Serializations 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model <http://dbpedia.org/resource/Pluto> "1930" <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> ● Turtle (Terse RDF Triple Language) Notation ○ extension of N-Triples @prefix dbo: <http://dbpedia.org/ontology/> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:discovered "1930" . <Pluto> dbo:discoverer <Clyde_Tombaugh> . RDF/Turtle allows shortcurts and abbreviations for readability
  20. 20. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● starting with N-Triples http://dbpedia.org/resource/Pluto "1930" http://dbpedia.org/ontology/discovered http://dbpedia.org/resource/Clyde_Tombaugh http://dbpedia.org/ontology/discoverer <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discovered> "1930" . <http://dbpedia.org/resource/Pluto> <http://dbpedia.org/ontology/discoverer> <http://dbpedia.org/resource/Clyde_Tombaugh> . @prefix dbo: <http://dbpedia.org/ontology/> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:discovered "1930" . <Pluto> dbo:discoverer <Clyde_Tombaugh> . @prefix directive associates prefix-label with URI @base directive provides URI to complement all relative URIs RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  21. 21. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Abbreviating RDF Triples in Turtle http://dbpedia.org/resource/Pluto "1930" http://dbpedia.org/ontology/discovered http://dbpedia.org/resource/Clyde_Tombaugh http://dbpedia.org/ontology/discoverer @prefix dbo: <http://dbpedia.org/ontology/> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:discovered "1930" ; dbo:discoverer <Clyde_Tombaugh> . semicolon indicates that subsequent triples have the same subject (predicate list) RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  22. 22. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Abbreviating RDF Triples in Turtle http://dbpedia.org/resource/Pluto http://dbpedia.org/resource/Hydra_(moon) dbo:satellite @prefix dbo: <http://dbpedia.org/ontology/> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:satellite <Hydra_(moon)> , <Nyx_(moon)> , <Charon_(moon)> . comma indicates that subsequent triples have same subject and property (object list) http://dbpedia.org/resource/Nyx_(moon) http://dbpedia.org/resource/Charon(moon) dbo:satellite dbo:satellite RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  23. 23. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Typed Literals http://dbpedia.org/resource/Pluto "1161.00"^^xsd:double dbo:meanRadius @prefix dbo: <http://dbpedia.org/ontology/> . @prefix xsd: <http://www.w3c.org/2001/XMLSchema#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:meanRadius "1161.00"^^xsd:double ; dbo:meanTemperature "44.00"^^xsd:double ; dbo:discovered "1930-02-18"^^xsd:date ; rdfs:label "Pluto"@en . "44.00"^^xsd:double "1930-02-08"^^xsd:date dbo:meanTemperature rdfs:label "Pluto"@en dbo:discovered RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  24. 24. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Multi Valued Relations ○ Pluto is visited by two spaceships on two different dates ○ How to model this in RDF? ○ Problem: unique association http://dbpedia.org/resource/Pluto New_Horizons dbo:spaceMission "2015-07-14"^^xsd:date USS_Enterprise_(NCC-1701) dbo:visited dbo:spaceMission dbo:visited "2245-07-14"^^xsd:date RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  25. 25. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology New_Horizons dbo:spaceMission "2015-07-14"^^xsd:date USS_Enterprise_(NCC-1701) dbo:visited dbo:spaceMission dbo:spaceShip "2245-07-14"^^xsd:date http://dbpedia.org/resource/Pluto dbo:visited dbo:spaceShip ● Multi Valued Relations ○ Blank Nodes (Bnodes) can be introduced to represent multi- valued relationships ○ Blank Nodes can be introduced for resources that don‘t need a name (auxiliary nodes) RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  26. 26. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology New_Horizons "2015-07-14"^^xsd:date dbo:visited dbo:spaceShip @prefix dbo: <http://dbpedia.org/ontology/> . @prefix xsd: <http://www.w3c.org/2001/XMLSchema#> . @base <http://dbpedia.org/resource/> . [] dbo:spaceShip <New_Horizons> ; dbo:visited "2015-07-14"^^xsd:date . anonymous blank node as subject RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  27. 27. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology @prefix dbo: <http://dbpedia.org/ontology/> . @prefix xsd: <http://www.w3c.org/2001/XMLSchema#> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:SpaceMission [ dbo:spaceShip <New_Horizons> ; dbo:visited "2015-07-14"^^xsd:date ] , [ dbo:spaceShip <USS_Enterprise_(NCC-1701)> ; dbo:visited "2245-07-14"^^xsd:date ] . New_Horizons dbo:spaceMission "2015-07-14"^^xsd:date USS_Enterprise_(NCC-1701) dbo:visited dbo:spaceMission dbo:spaceShip "2245-07-14"^^xsd:date http://dbpedia.org/resource/Pluto dbo:visited dbo:spaceShip nested anonymous blank nodes RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  28. 28. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology @prefix dbo: <http://dbpedia.org/ontology/> . @prefix xsd: <http://www.w3c.org/2001/XMLSchema#> . @base <http://dbpedia.org/resource/> . <Pluto> dbo:SpaceMission _:ID1, _:ID2 . _:ID1 dbo:spaceShip <New_Horizons> ; dbo:visited "2015-07-14"^^xsd:date . _:ID2 dbo:spaceShip <USS_Enterprise_(NCC-1701)> ; dbo:visited "2245-07-14"^^xsd:date . New_Horizons dbo:spaceMission "2015-07-14"^^xsd:date USS_Enterprise_(NCC-1701) dbo:visited dbo:spaceMission dbo:spaceShip "2245-07-14"^^xsd:date ID1http://dbpedia.org/resource/Pluto ID2 dbo:visited dbo:spaceShip dereferenceable blank nodes can only be referenced from inside a document / graph RDF/Turtle 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model
  29. 29. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology More RDF Datastructures 3. Linked Data Engineering / 3.5 Resource Description Framework (RDF) as simple Data Model ● RDF Containers and RDF Collections ○ Data structures to enumerate any resources or literals ○ Open lists (RDF Containers) and closed lists (RDF Collections) ○ No new semantics, just “syntactic sugar” ● RDF Reification ○ Abstraction for making “statements about RDF triples” ○ Useful for modeling data provenance ■ e.g. to model “DBpedia states that Pluto has been discovered in 1930.”
  30. 30. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 7: Linked Data Engineering - 2 3.1 Knowledge Representations and Ontologies 3.2 Semantic Web and the Web of Data 3.3 Linked Data Principles 3.4 How to name Things - URIs 3.5 Resource Description Framework (RDF) as simple Data Model 3.6 Creating new Models with RDFS 3.7 Querying RDF(S) with SPARQL 3.8 More Expressivity with Web Ontology Language (OWL) 3.9 Wikipedia, DBpedia, and Wikidata 3.10 Linked Data Programming
  31. 31. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology What does it really mean? http://dbpedia.org/resource/Pluto http://dbpedia.org/resource/Charon_(moon) http://dbpedia.org/property/satelliteOf http://dbpedia.org/resource/Clyde_Tombaugh http://dbpedia.org/ontology/discoverer Where does the intended meaning really come from?
  32. 32. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology What does it really mean? http://dbpedia.org/resource/Pluto http://dbpedia.org/resource/Charon_(moon) http://dbpedia.org/property/satelliteOf something which can be uniquely identified via the URI http://dbpedia.org/resource/Pluto something which can be uniquely identified via the URI http://dbpedia.org/resource/Charon_(moon) but the URI for the same resource could also be http://dbpedia.org/resource/Q142 but the URI for the same resource could also be http://dbpedia.org/resource/Q141 http://dbpedia.org/property/Q144 We need more semantic expressivity...
  33. 33. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology RDF Schema
  34. 34. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● RDF Schema, officially called “RDF Vocabulary Description Language” ● RDF Schema allows: ○ Definition of classes via rdfs:Class ○ Class instantiation in RDF via rdf:type ○ Example: :Planet rdf:type rdfs:Class . :Earth rdf:type :Planet . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix : <http://example.org/Space#> . RDF Schema 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  35. 35. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Definition of properties via rdf:Property ● Definition of property restrictions on domain and range via rdfs:domain and rdfs:range ● Example :CelestialBody rdf:type rdfs:Class . :satelliteOf rdf:type rdf:Property . :satelliteOf rdfs:domain :CelestialBody . :satelliteOf rdfs:range :CelestialBody . RDF Schema 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  36. 36. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Everything in the RDF model is a resource ○ rdfs:Class rdf:type rdfs:Resource . ○ rdf:Property rdf:type rdfs:Resource . ○ rdfs:Literal rdf:type rdfs:Resource . ○ rdfs:XMLLiteral rdf:type rdfs:Resource . ○ rdfs:Datatype rdf:type rdfs:Resource . RDF Schema 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  37. 37. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Definition of hierarchical relationships: ○ Subclasses and superclasses via rdfs:subClassOf ○ Example: :Planet rdfs:subClassOf :CelestialBody . :CelestialBody :Planet RDF Schema 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  38. 38. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Definition of hierarchical relationships: ○ Subclasses and superclasses via rdfs:subClassOf ○ Example: :Planet rdfs:subClassOf :CelestialBody . ○ Subproperties and superproperties via subPropertyOf ○ Example :artificialSatelliteOf rdfs:subPropertyOf :satelliteOf . RDF Schema 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  39. 39. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology rdfs:Resource rdf:type rdfs:comment rdfs:subClassOf rdfs:subPropertyOf rdfs:domain rdfs:range rdf:XMLLiteral ● instance relation ● subclass relation http://www.w3.org/TR/rdf-schema/#ch_classes rdfs:Class rdfs:Literal rdf:Propertyrdfs:Datatype RDFS Language Model 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  40. 40. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Some more properties: ○ rdfs:seeAlso defines a relation of a resource to another, which explains it ○ rdfs:isDefinedBy subproperty of rdfs:seeAlso, defines the relation of a resource to its definition ○ rdfs:comment comment, usually as text ○ rdfs:label „readable“ name of a resource (contrary to ID) RDF Schema 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  41. 41. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Instance Definitions Property Definitions Class Definitions @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix : <http://example.org/Space#> . :Planet rdf:type rdfs:Class ; rdfs:subClassOf :CelestialBody . :Satellite rdf:type rdfs:Class ; rdfs:subClassOf :CelestialBody . :ArtificialSatellite rdf:type rdfs:Class ; rdfs:subClassOf :Satellite . :satelliteOf rdf:type rdf:Property ; rdfs:domain :CelestialBody . rdfs:range :CelestialBody . :Earth rdf:type :Planet . :Moon rdf:type :Satellite ; :satelliteOf :Earth . :Sputnik1 rdf:type :ArtificialSatellite ; :satelliteOf :Earth ; rdfs:label "Sputnik 1"@en ; rdfs:comment "the first artificial Earth satellite in 1957" . RDFS Example 3. Linked Data Engineering / 3.6 Creating new Models with RDFS
  42. 42. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 7: Linked Data Engineering - 2 3.1 Knowledge Representations and Ontologies 3.2 Semantic Web and the Web of Data 3.3 Linked Data Principles 3.4 How to name Things - URIs 3.5 Resource Description Framework (RDF) as simple Data Model 3.6 Creating new Models with RDFS 3.7 Querying RDF(S) with SPARQL 3.8 More Expressivity with Web Ontology Language (OWL) 3.9 Wikipedia, DBpedia, and Wikidata 3.10 Linked Data Programming
  43. 43. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology SPARQL
  44. 44. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology user interface SPARQL Query Language SPARQL Endpoint Client Server SPARQL Protocol Layer HTTP SPARQL - A Query Language for RDF(S) 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  45. 45. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology SPARQL Endpoint Example 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL http://dbpedia.org/sparql
  46. 46. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● SPARQL Protocol and RDF Query Language is ○ a Query Language for RDF graph traversal (SPARQL Query Language Specification) ○ a Protocol Layer, to use SPARQL via http (SPARQL Protocol for RDF Specification) ○ an XML Output Format Specification for SPARQL queries (SPARQL Query XML Results Format) ○ W3C Standard (SPARQL 1.1, Mar 2013) ○ inspired by SQL SPARQL - A Query Language for RDF(S) 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  47. 47. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology SPARQL Result SPARQL Query ● SPARQL Variables are bound to RDF terms ○ e.g. ?title, ?author, ?address ● In the same way as in SQL, a Query for variables is performed via SELECT statement ○ e.g. SELECT ?title ?author ?published ● A SELECT statement returns Query Results as a table ?title ?author ?published 1984 George Orwell 1948 Brave New World Aldous Huxley 1932 Fahrenheid 451 Ray Bradbury 1953 For Queries we need Variables 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  48. 48. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● SPARQL is based on RDF Turtle serialization and basic graph pattern matching. ● A Graph Pattern (Triple Pattern) is a RDF Triple that contains variables at any arbitrary place (Subject, Property, Object). (Graph) Triple Pattern = Turtle + Variables ● Example: Look for countries and their capitals: ?country dbo:capital ?capital . ● A Basic Graph Pattern (BGP) is a set of Triple Pattern SPARQL Graph Pattern Matching 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  49. 49. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Triple Pattern ?country dbo:capital ?capital . RDF Graph dbpedia:Venezuela rdf:type dbo:Country . dbpedia:Venezuela dbo:capital dbpedia:Caracas . dbpedia:Venezuela dbprop:language “Spanish“ . dbpedia:Germany rdf:type dbo:Country . dbpedia:Germany dbo:capital “Berlin“ . dbpedia:Germany dbp:language “German“ . ... SPARQL - A Query Language for RDF(S) 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  50. 50. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● SPARQL Graph Pattern can be combined to form complex (conjunctive) queries for RDF graph traversal ● Find countries, their capitals, and their population count: ?country dbo:capital ?capital . ?country dbo:population ?population . ● Given a FOAF URI, find the name of a person and her friends: <http://hpi-web.de/id#haraldsack> foaf:name ?surname ; foaf:knows ?friend . ?friend foaf:name ?friend_surname . SPARQL Complex Query Pattern 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  51. 51. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● search all authors and the titles of their notable works: PREFIX : <http://dbpedia.org/resource/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX dbo: <http://dbpedia.org/ontology/> SELECT ?author_name ?title FROM <http://dbpedia.org/> WHERE { ?author rdf:type dbo:Writer . ?author rdfs:label ?author_name . ?author dbo:notableWork ?work . ?work rdfs:label ?title . } specifies namespaces specifies output variables specifies graph to be queried specifies graph pattern to be matched SPARQL General Query Format 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  52. 52. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● search all authors and the titles of their notable works ordered by authors in ascending order and limit the results to the first 100 results starting the list at offset 10 position: PREFIX : <http://dbpedia.org/resource/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX dbo: <http://dbpedia.org/ontology/> SELECT ?author_name ?title FROM <http://dbpedia.org/> WHERE { ?author rdf:type dbo:Writer . ?author rdfs:label ?author_name . ?author dbo:notableWork ?work . ?work rdfs:label ?title . } ORDER BY ASC (?author_name) LIMIT 100 OFFSET 10 solution sequence modifiers query SPARQL endpoint SPARQL General Query Format 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  53. 53. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● FILTER expressions contain operators and functions PREFIX : <http://dbpedia.org/resource/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX dbo: <http://dbpedia.org/ontology/> SELECT ?author_name ?title ?pages FROM <http://dbpedia.org/> WHERE { ?author rdf:type dbo:Writer . ?author rdfs:label ?author_name . ?author dbo:notableWork ?work . ?work dbo:numberOfPages ?pages . FILTER (?pages > 500) ?work rdfs:label ?title . } LIMIT 100 specifies constraints for the result query SPARQL endpoint SPARQL Filter Constraints 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  54. 54. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Operator Type(A) Result Type !A xsd:boolean xsd:boolean +A numeric numeric -A numeric numeric BOUND(A) variable xsd:boolean isURI(A) RDF term xsd:boolean isBLANK(A) RDF term xsd:boolean isLITERAL(A) RDF Term xsd:boolean STR(A) literal/URL simple literal LANG(A) literal simple literal DATATYPE(A) literal URI SPARQL Unary Operators 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  55. 55. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● Example: Filter results only for English labels PREFIX : <http://dbpedia.org/resource/> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX dbo: <http://dbpedia.org/ontology/> SELECT ?author_name ?title ?pages FROM <http://dbpedia.org/> WHERE { ?author rdf:type dbo:Writer . ?author rdfs:label ?author_name FILTER (LANG(?author_name)="en"). ?author dbo:notableWork ?work . ?work dbo:numberOfPages ?pages . FILTER (?pages > 500) ?work rdfs:label ?title . FILTER (LANG(?title)="en") } LIMIT 100 query SPARQL endpoint SPARQL Filter Constraints 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  56. 56. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● From Wikipedia to DBpedia e.g. from http://en.wikipedia.org/wiki/George_Orwell to http://dbpedia.org/page/George_Orwell ● Browsing DBpedia e.g. using http://dbpedia.org/page/George_Orwell as a starting point to learn more about DBpedia structure and DBpedia ontologies ● Using DBpedia Sparql Endpoint with http://dbpedia.org/sparql and query DBpedia via SPARQL SPARQL - First Hands On 3. Linked Data Engineering / 3.7 Querying RDF(S) with SPARQL
  57. 57. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Next Lecture: Linked Data Engineering - 3 3.1 Knowledge Representations and Ontologies 3.2 Semantic Web and the Web of Data 3.3 Linked Data Principles 3.4 How to name Things - URIs 3.5 Resource Description Framework (RDF) as simple Data Model 3.6 Creating new Models with RDFS 3.7 Querying RDF(S) with SPARQL 3.8 More Expressivity with Web Ontology Language (OWL) 3.9 Wikipedia, DBpedia, and Wikidata 3.10 Linked Data Programming
  58. 58. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering - 2 Bibliography ● E. Prud'hommeaux, G. Carothers, RDF 1.1 Turtle, Terse RDF Triple Language, W3C Recommendation 25 February 2014 https://www.w3.org/TR/turtle/ ● S. Hitzler, S. Rudolph, Foundations of Semantic Web Technologies, Chapman / Hall, 2009.
  59. 59. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering - 2 Syllabus Questions ● What are RDF blank nodes used for? ● What is the difference between RDF blank nodes and regular RDF nodes? ● Why is RDF alone not sufficient for knowledge representation? ● What is RDFS used for? ● What is SPARQL? ● What is a Graph Triple Pattern? ● Explain how - in principle - a SPARQL query is carried out ● What is the general SPARQL query format?
  60. 60. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering - 2 Lecture / Lab Course Evaluation Evaluation Office: Kaiserstrasse 12, Geb. 10.11, Raum 013, Office hours: 9am - 5.30pm

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