OpenHPI 2.2 - How to Represent Facts - RDF

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OpenHPI 2.2 - How to Represent Facts - RDF

  1. 1. Semantic Web TechnologiesLecture 2: Semantic Web - Basic Architecture I 02: How to Represent Facts? - RDF(1) Dr. Harald Sack Hasso Plattner Institute for IT Systems Engineering University of Potsdam Spring 2013 This file is licensed under the Creative Commons Attribution-NonCommercial 3.0 (CC BY-NC 3.0)
  2. 2. 2Lecture 2: Semantic Web - Basic Architecture I Open HPI - Course: Semantic Web Technologies Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  3. 3. Intr3 odu ctio n 02 How to Represent Facts? - RDF (1)Open HPI - Course: Semantic Web Technologies - Lecture 2: Semantic Web Basic Architecture I Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  4. 4. Tim Berners-Lee: W3 future directions, Plenary at 1st WWW Conference, 1994, Geneva (Switzerland)Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  5. 5. To a computer, then, the web is a flat, boring world devoid of meaning. This is a pity, as in fact documents on the web describe real objects and imaginary concepts, and give particular relationships between them. For example, a document might describe a person. The title document to a house describes a house and also the ownership relation with a person. [...] Tim Berners-Lee: W3 future directions, Plenary at 1st WWW Conference, 1994, Geneva (Switzerland)Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  6. 6. 2. Semantic Web Basic Architecture The Languages of the Semantic Web - Part 15 Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  7. 7. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  8. 8. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ <phonenr> <owner>Harald Sack</owner> <number>++49 (331) 5509-927</number> </phonenr> Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  9. 9. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ <phonenr> <owner>Harald Sack</owner> <number>++49 (331) 5509-927</number> </phonenr> <person name=“Harald Sack“> <phonenr>49 (331) 5509-927</phonenr> </person> Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  10. 10. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ <phonenr> <owner>Harald Sack</owner> <number>++49 (331) 5509-927</number> </phonenr> <person name=“Harald Sack“> <phonenr>49 (331) 5509-927</phonenr> </person> <person name=“Harald Sack“ phone=“49 (331) 5509-927“ /> Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  11. 11. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ <phonenr> <owner>Harald Sack</owner> <number>++49 (331) 5509-927</number> </phonenr> <person name=“Harald Sack“> <phonenr>49 (331) 5509-927</phonenr> </person> <person name=“Harald Sack“ phone=“49 (331) 5509-927“ /> is there a unique (intuitive) way to model knowledge? Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  12. 12. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ Harald Sack Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  13. 13. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ Harald Sack has the phone number Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  14. 14. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ Harald Sack has the phone number ++49 (331) 5509-927 Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  15. 15. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ ■ Intuitive knowledge representation with directed graphs Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  16. 16. Knowledge Representation... a simple example ■ How do I represent: „Harald Sack has the phone number ++49 (331) 5509-927“ ■ Intuitive knowledge representation with directed graphs Harald Sack ++49 (331) 5509-927 has phone number Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  17. 17. Knowledge Representationin the Semantic Web XML XMLSchema Level 1 (objects) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  18. 18. Knowledge Representationin the Semantic Web RDF & RDFSchema Level 2(knowledge about XML objects) XMLSchema Level 1 (objects) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  19. 19. Knowledge Representationin the Semantic Web Level 3 OWL & Rules (entire worlds) RDF & RDFSchema Level 2(knowledge about XML objects) XMLSchema Level 1 (objects) Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  20. 20. 10 D F R Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  21. 21. Resource11 Description Framework Resource ■ can be everything (in principle)... ■ must be uniquely identified and be referencable ■ ...simply via URI Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  22. 22. Resource12 Description Framework Description ■ = Descriptions of resources ■ ...via representing properties and relationships among resources ■ ...relationships can be represented as graphs Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  23. 23. Resource13 Description Framework Framework ■ = Combination of web based protocols (URI, HTTP, XML,...) ■ based on formal model (semantics) ■ defines all allowed relationships among resources Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  24. 24. Resource14 Description Framework Harald Sack Subject has phone number Property ++49 (331) 5509-927Object Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  25. 25. Resource15 Description Framework Harald Sack has phone number ++49 (331) 5509-927 ■ Knowledge in RDF is expressed as a list of statements ■ all RDF statements follow the same simple schema Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  26. 26. Resource16 Description Framework Harald Sack Subject has phone number Property ++49 (331) 5509-927Object Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  27. 27. Resource17 Description Framework • Resources: Objects that can be addressed via URI • Properties: Attributes for the description of resources • Statements (RDF-Triple): Resource + Property + Object / Value URI URI URI / Literal Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  28. 28. Resource18 Description Framework Constituents of the RDF-Graph • URI: • to reference resources uniquely http://hpi-web.de/HaraldSack http://semweb2013.blogspot.com/ S O http://hpi-web.de/Personal#writesBlog P Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  29. 29. Resource19 Description Framework Constituents of the RDF-Graphen • Literals: • describe data values that do not have a separate existence • strings, interpretation via datatype http://hpi-web.de/HaraldSack ++49-331-5509-927 S O http://hpi-web.de/Personal#hasPhoneNumber P Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  30. 30. Resource20 Description Framework Constituents of the RDF-Graphen • Literals: • typed literals can be expressed via XML Schema datatypes • Namespace for typed literals: http://www.w3.org/2001/XMLSchema# • Example: “Semantics“^^<http://www.w3.org/2001/XMLSchema#string> • Language Tags denote the (natural) language of the text: • Example: “Semantik“@de , “Semantics“@en Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  31. 31. Resource21 Description Framework Constituents of the RDF-Graphen • Blank Nodes: • Denotes existence of an individual with specific attributes, but without providing an identification or reference http://www.hpi-web.de/personal#person S O rdf:type P Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  32. 32. Resource22 Description Framework RDF Representations • Node-Edge-Node Triple http://hpi-web.de/HaraldSack http://semweb2013.blogspot.com/ S O http://hpi-web.de/Personal#writesBlog P Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  33. 33. Resource23 Description Framework RDF Representations • N3 Notation • Simple listing of triples • { http://hpi-web.de/HaraldSack, http://hpi-web.de/Personal#writesBlog, http://semweb2013.blogspot.com/ } Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  34. 34. Resource24 Description Framework RDF Representations • Turtle (Terse RDF Tripel Language) • Extension of N3 • URIs in angle brackets <Subject> <Prop erty> <Object> <Subject> <Prop . • Literals in quotation marks erty> “Object“ . • Triple ends with a period • Whitespaces will be ignored Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  35. 35. Resource25 Description Framework RDF Representations • Turtle (Terse RDF Tripel Language) <http://hpi-web.de/HaraldSack> <http://hpi-web.de/Personal#writesBlog> <http://semweb2013.blogspot.com/>. <http://hpi-web.de/HaraldSack> <http://hpi-web.de/Personal#hasPhoneNumber> “++49-331-5509-927“. Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  36. 36. Resource26 Description Framework RDF Representations • Turtle (Terse RDF Tripel Language) @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . @prefix dc: <http://purl.org/dc/elements/1.1/> . @prefix ex: <http://example.org/stuff/1.0/> . <http://www.w3.org/TR/rdf-syntax-grammar> dc:title "RDF/XML Syntax Specification (Revised)"@en ; ex:editor [ ex:fullname "Dave Beckett"^^xsd:string ; ex:homePage <http://purl.org/net/dajobe/> ]. Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  37. 37. Resource Description Framework27 RDF Representations • RDF XML-Serialization <xml version=“1.0“ encoding=“utf-8“> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#“ xmlns:pers=“http://hpi-web.de/Personal#“> <rdf:Description rdf:about=“http://hpi-web.de/HaraldSack“> <pers:hasPhoneNr>++49-331-5509-927</pers:hasPhoneNumber> </rdf:Description> <rdf:Description rdf:about=“http://hpi-web.de/HaraldSack“> <pers:writesBlog> <rdf:Description rdf:about=“http://semweb2013.blogspot.com/“></rdf:Description> </pers:writesBlog> </rdf:Description> </rdf:RDF> Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam
  38. 38. Sim28 ple Fac ts i n R DF 03 How to Represent Facts? - RDF (2)Open HPI - Course: Semantic Web Technologies - Lecture 2: Semantic Web Basic Architecture I Semantic Web Technologies , Dr. Harald Sack, Hasso-Plattner-Institut, Universität Potsdam

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