06 Linked Data Engineering - 1

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Lecture 6, Linked Data Engineering, URI, COntent NEgotiation, RDF

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06 Linked Data Engineering - 1

  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 6: Linked Data Engineering - 1 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: Natural Language Processing (4) 2.1 NLP and Basic Linguistic Knowledge 2.2 NLP Applications 2.3 NLP Techniques 2.4 NLP Challenges 2.5 Evaluation, Precision and Recall 2.6 Regular Expressions 2.7 Finite State Automata 2.8 Tokenization 2.9 Language Model and N-Grams 2.10 Part-of-Speech Tagging ● Language Model and N-grams ● Markov Assumption ● Text Corpora ● Maximum Likelihood Estimation ● Average Branching Factor ● Smoothing ● POS-Tagging ● Word Categories ● Hidden Markov Models
  3. 3. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering 3. Linked Data Engineering
  4. 4. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 6: 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) 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
  5. 5. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Understanding Information PLUTO Never Forget! (1930-2006) https://solarsystem.nasa.gov/multimedia/gallery/01_Stern_03_Pluto_Color_TXT.jpg
  6. 6. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technologyhttps://solarsystem.nasa.gov/multimedia/gallery/01_Stern_03_Pluto_Color_TXT.jpg PLUTO Never Forget! (1930-2006)
  7. 7. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Text: ”Pluto“ Entity Mapping Disambiguation Pluto a Disney cartoon character Pluto a Roman god Pluto a song by Björk HMS Pluto a shipDisambiguation ● solution of linguistic ambiguities Pluto a dwarf planet ... Information Understanding 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies
  8. 8. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Text: ”Pluto“ Entity Mapping Pluto Entity Dwarf Planet is a Class Planet is a subclass of Class ● The Meaning (Semantics) of entities and classes must be defined explicitly. Understanding Information 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies
  9. 9. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Pluto Dwarf Planet Planet is a subclass of ● The Meaning (Semantics) is expressed with the help of knowledge representations (Ontologies) Natural Object Astronomical Objects discovered in 1930 CelestialBody Minor Planets visited by Spacecraft (more classes) is a is a subclass ofis a is a Logical Inference Understanding Information 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies
  10. 10. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Pluto Planet ● The Meaning (Semantics) is expressed with the help of knowledge representations (Ontologies) name string radius integer discovered date / time discoverer Person is a domain range range range range domain domain domain classes classesproperties Understanding Information 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies
  11. 11. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology What is Knowledge? 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies Beliefs Truths Knowledge Traditional Definition: „Knowledge is a subset of all true beliefs“ To represent knowledge, we need a formal knowledge representation => Ontologies
  12. 12. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Ontologies in Computer Science 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies "An ontology is an explicit, formal specification of a shared conceptualization. The term is borrowed from philosophy, where an Ontology is a systematic account of existence. For AI systems, what ‘exists’ is that which can be represented.“ according to Thomas R. Gruber: A Translation Approach to Portable Ontology Specifications.Knowledge Acquisition, 5(2):199-220, 1993. conceptualization: abstract model (domain, identified relevant concepts, relations) explicit: meaning of all concepts must be defined formal: machine understandable shared: consensus about ontology
  13. 13. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology How to represent Ontologies? 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies ● Ontologies can be represented via Classes, Relations and Instances ● Classes are abstract groups, sets, or collections of objects and represent ontology concepts ● Classes are characterised via attributes ● Attributes are name-value pairs „The address contains the name, title, and place of residence of the person addressed“ informal description Address • given name <string> • family name <string> • street <string> • ZIP code <int> • city <string> • … semi-formal description
  14. 14. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology How to represent Ontologies? 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies ● Classes can be related to other classes ● Relations are special attributes, whose values are objects of (other) classes Celestial Body Planet Artificial Satellite Space Mission Name Mission to the Moon has name is subClass of is subClass of is visited by is part of is subClass of
  15. 15. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology How to represent Ontologies? 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies ● For Relations and Attributes Rules (Constraints) can be defined that determine allowed/valid values Person Astronaut Student Address hasAddress is subClass of is subClass of Woman Man is subClass of is subClass of Woman ⋂ Man = ∅ constraint n : m 1 : 1
  16. 16. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology How to represent Ontologies? 3. Linked Data Engineering / 3.1 Knowledge Representations and Ontologies ● Instances describe individuals of an ontology Artificial Satellite Celestial Body is subClass of dbr:New_Horizons “New Horizons” hasTitle Pluto has target is a Terminological Knowledge Assertional Knowledge Dwarf Planet is a is subClass of
  17. 17. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 6: 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) 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
  18. 18. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● The Web of Data is an upgrade of the Web of Documents ● It’s the Web as a huge decentralised database (knowledge base) of machine-accessible data Third Generation: The Web of Data Data Centered Processing „The web of human-readable document is being merged with a web of machine understandable data. The potential of the mixture of humans and machines working together and communication through the web could be immense.“ Tim Berners-Lee, The World Wide Web: A very short personal history, May 1998 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data
  19. 19. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology ● How does the user access the information? Advantages ● Information can be automatically selected, aggregated, remixed and published according to personal preferences personal assistant intelligent Infrastructure services user Information aggregation & filtering Third Generation: The Web of Data Data Centered Processing 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data http://lod-cloud.net/versions/2017-02-20/lod.svg
  20. 20. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 1. Identification (URI) & address (URL) e.g. http://kit.edu URL HTTP address 2. Communication / protocol (HTTP) GET /index HTTP/2 Host: kit.edu HTML reference communication WEB 3. Representation language (HTML) Rima studies at <a href=”http://kit.edu”>KIT</a>. Thanks to http://www.slideshare.net/fabien_gandon The Basic Architecture of the Web 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data
  21. 21. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Linked Data and the Web of Data 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data Where do the Links come from…? ...and what do they mean?
  22. 22. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web and the Web of Data 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data ● The meaning of information (Semantics) is made explicit by formal (structured) and standardized knowledge representations (Ontologies). ● Thus it will be possible, ○ to process the meaning of information automatically ○ to relate and integrate heterogeneous data ○ to deduce implicit (not evident) information from existing (evident) information in an automated way ● The Semantic Web is kind of a global database that contains a universal network of semantic propositions.
  23. 23. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web and the Web of Data 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data „The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation" Tim Berners-Lee, James Hendler, Ora Lassila: The Semantic Web, Scientific American, 284(5), pp. 34-43(2001)
  24. 24. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.1 The Web of Data
  25. 25. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web Technology Stack 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data http://dbpedia.org/resource/PlutoPluto URI - Uniform Resource Identifier
  26. 26. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web Technology Stack 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data RDF Resource Description Framework :Pluto rdf:type dbo:Planet . :Pluto foaf:name “Pluto”@en . :Pluto dbo:discoverer :Clyde_Tombaugh . :Pluto dbo:discovered “1930-02-18”^^xsd:date . :Clyde_Tombaugh rdf:type dbo:Person . :Clyde_Tombaugh dbo:birthdate “1906-02-04”^^xsd:date . ... :Pluto rdf:type dbo:Planet . RDF Subject RDF Property RDF ObjectRDF Triple http://dbpedia.org/resource/Pluto
  27. 27. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web Technology Stack 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data RDF Schema dbo:Planet rdf:type owl:class . dbo:Planet rdfs:subClassOf dbo:CelestialBody . dbo:discovered rdf:type rdf:Property . dbo:discovered rdfs:domain owl:Thing . dbo:discovered rdfs:range xsd:date . dbo:discoverer rdf:type rdf: Property . dbo:discoverer rdfs:domain owl:Thing . dbo:discoverer rdfs:rang dbo:Person . ... http://dbpedia.org/ontology/Planet Planet Person dbo:discoverer CelestialBody rdfs:subClassOf
  28. 28. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web Technology Stack 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data logical constraint Person Pluto Clyde_Tombaugh dbo:discoverer new:LivingPeople new:DeadPeople∩ = ∅ rdf:type rdfs:subClassOf ∀x.∃y.deathDate(x,y) ∧Person(x)∧Date(y) → DeadPeople(x) description logics + logical rules classes entities
  29. 29. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web Technology Stack 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data try SPARQL query at public DBpedia SPARQL endpoint Look for all Astronauts who have been on a Space Mission which ended in a Desaster PREFIX dcterms: <http://purl.org/dc/terms/> PREFIX dbp: <http://dbpedia.org/property/> PREFIX dbc: <http://dbpedia.org/resource/Category:> SELECT distinct ?astronaut ?mission FROM <http://dbpedia.org/> WHERE { ?astronaut rdf:type dbo:Astronaut; dbp:mission ?mission . ?mission dcterms:subject dbc:Space_accidents_and_incidents . }
  30. 30. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Semantic Web Technology Stack 3. Linked Data Engineering / 3.2 Semantic Web and the Web of Data Look for all Astronauts who have been on a Space Mission which ended in a Desaster try SPARQL query at public DBpedia SPARQL endpoint
  31. 31. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 6: 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) 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
  32. 32. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Web of Data and how we make use of it 3. Linked Data Engineering / 3.3 Linked Data Principles Linked Data ● Linked Open Data (LOD) denote publicly available (RDF) Data in the Web, identified via URI and accessible via HTTP. Linked data link to other data via URI. The Web of Data ● 9,960 datasets ● >149 billion facts ● >800 million links (April 2017) http://stats.lod2.eu/ http://lod-cloud.net/
  33. 33. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology http://www.bbc.co.uk/music
  34. 34. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Data Access in the traditional Web 3. Linked Data Engineering / 3.3 Linked Data Principles ● Data can only be found on the Web, if it is available at some website Browser Web Server JDBC HTTP
  35. 35. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Data Access in the traditional Web 3. Linked Data Engineering / 3.3 Linked Data Principles ● There is a number of different (proprietary) Web APIs, data exchange formats, and Mashups on top of that Database 1 Database 2 Database 3 Database 4 Web API 1 Web API 2 Web API 3 Web API 4 Mashup
  36. 36. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology In the traditional Web... 3. Linked Data Engineering / 3.3 Linked Data Principles ● Data is locked up in small data islands ● Other applications usually cannot access this data... Database Database Database Database Database Database Database Database Database Database
  37. 37. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Data Access in the traditional Web 3. Linked Data Engineering / 3.3 Linked Data Principles http://www.w3.org/2009/Talks/0204-ted-tbl/#(22)
  38. 38. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology How to get rid of Closed Data Island? 3. Linked Data Engineering / 3.3 Linked Data Principles ● Apply Linked Data technology ○ to publish (structured) data on the web ○ to draw connections from one data source to data from other data sources Database 1 Database 2 Database 3 Database 4 RDF data RDF data RDF data RDF data
  39. 39. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Linked Data Principles 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, SPARQL) 4. Include links to other URIs, so that they can discover more things. (Tim Berners-Lee, Linked Data, 2006, http://www.w3.org/DesignIssues/LinkedData.html)
  40. 40. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology The Benefit of using Linked Data at BBC Music Website ● Information is dynamically aggregated from external, publicly available data (Wikipedia, MusicBrainz, Last.FM, Discogs,...) ● no Screen Scraping ● no specialized API ● all data available as Linked Open Data ● data access via simple HTTP Request ● data is always up-to-date without manual interaction
  41. 41. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Linked Open Data 3. Linked Data Engineering / 3.3 Linked Data Principles ○ Public Linked Data resources in the Web, licensed as Creative Common CC-BY ○ Tim Berners-Lee‘s 5-Star Criteria for Linked Open 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: link your data to other people’s data to provide context ★★★★ All the above plus: use open standards from W3C (RDF and SPARQL) to identify things, so that people can point at your stuff
  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 6: 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) 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 What is this?
  44. 44. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology
  45. 45. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Semiotic Triangle 3. Linked Data Engineering / 3.4 How to name Things - URIs sender receiver is a substitute for Symbol Object stands for refers tosymbolizes “apple” Concept shared concept Ogden, Richards: Semiotic Triangle, 1923
  46. 46. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Uniform Resource Identifier 3. Linked Data Engineering / 3.4 How to name Things - URIs ● A Uniform Resource Identifier (URI) defines a simple and extensible schema for worldwide unique identification of abstract or physical resources (RFC 3986). ● A Resource can be every object with a clear identity (according to the context of the application) ○ as e.g., web pages, books, locations, persons, relations among objects, abstract concepts, etc. ● URI concept is already established in various domains, as e.g., ○ the Web (URL), ○ Books and publications (ISBN, ISSN), ○ Digital Object Identifier (DOI)
  47. 47. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology URL URI identify on the web what exists identify what exists on the web http://www.mywebsite.org/ http://hpi.de/harald_foaf.rdf#me Thanks to http://www.slideshare.net/fabien_gandon
  48. 48. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Linked Data and the Web 3. Linked Data Engineering / 3.4 How to name Things - URIs URI HTTP address HTML reference communication WEB
  49. 49. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technologyhttp://commons.wikimedia.org/wiki/File:Eiffel_tower_from_trocadero.jpg Resource http://www.tour-eiffel.fr/ URI identifies Metadata: Content-type: text/html Data: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>Le site officiel de la Tour Eiffel</title> ... </html> represents (stands for) Representation Presentation defines The Eiffel Tower is described (designated) by the web page Designator Designatum describes
  50. 50. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.4 How to name Things - URIs http://commons.wikimedia.org/wiki/File:Eiffel_tower_from_trocadero.jpg What if a URI does not exist (yet)? ● Define a URI by yourself: ○ avoid overlaps → use your own website as namespace ○ enable documentation at the same place → HTTP Content Negotiation ● Use separate URIs for the resource (Designatum) and its documentation (Designator) via ○ HTTP Content Negotiation and/or ○ URI references (e.g. via "#" fragment identifier)
  51. 51. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.4 How to name Things - URIs HTTP Content Negotiation Let‘s try an example: ● I want to have information about the Eiffel Tower from DBpedia http://dbpedia.org/ resource/Eiffel_Tower http://dbpedia.org/ page/Eiffel_Tower 1 2 HTTP/2 303 See Other HTTP GET request Accept Header: text/html URI represents Designator3 HTTP GET request Accept Header: text/html URI represents Designatum HTML Document4 http://commons.wikimedia.org/wiki/File:Eiffel_tower_from_trocadero.jpg
  52. 52. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.4 How to name Things - URIs HTTP Content Negotiation Let‘s try another example: ● I want to have machine readable information about the Eiffel Tower from DBpedia http://dbpedia.org/ resource/Eiffel_Tower http://dbpedia.org/ data/Eiffel_Tower 1 2 HTTP/2 303 See Other HTTP GET request Accept Header: application/rdf+xml URI represents Designator3 URI represents Designatum RDF Document4 HTTP GET request Accept Header: application/rdf+xml http://commons.wikimedia.org/wiki/File:Eiffel_tower_from_trocadero.jpg
  53. 53. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.4 How to name Things - URIs HTTP Content Negotiation Let‘s try it ourselves: ● I want to have information about the Eiffel Tower from DBpedia ● I want to have machine readable information about the Eiffel Tower from DBpedia curl -L -H "Accept: text/html" http://dbpedia.org/resource/Eiffel_Tower curl -L -H "Accept: application/rdf+xml" http://dbpedia.org/resource/Eiffel_Tower
  54. 54. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.4 How to name Things - URIs Linked Data and the Web URI HTTP address HTML reference communication WEB
  55. 55. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Linked Data Principles 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, SPARQL) 4. Include links to other URIs, so that they can discover more things. (Tim Berners-Lee, Linked Data, 2006, http://www.w3.org/DesignIssues/LinkedData.html)
  56. 56. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering / 3.4 How to name Things - URIs Linked Data and the Web URI HTTP address RDF reference communication WEB of Data
  57. 57. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 6: 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) 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 / 3.5 Resource Description Framework (RDF) as simnple Data Model How to represent knowledge? intuitive knowledge representation with a directed graph ● How do I represent the following fact: “Pluto has been discovered in 1930” in an intuitive way? Plutosubject has been discovered inpredicate 1930object
  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 / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework URI or Literal URI URIPlutosubject has been discovered inpredicate 1930object
  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 / 3.5 Resource Description Framework (RDF) as simnple Data Model Resource Description Framework ● RDF Statements (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
  61. 61. 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> “1930” <http://dbpedia.org/ontology/discovered> <http://dbpedia.org/resource/Clyde_Tombaugh> <http://dbpedia.org/ontology/discoverer> “1906-02-04” <http://dbpedia.org/ontology/birthdate> <http://dbpedia.org/resource/Streator,_Illinois> <http://dbpedia.org/ontology/birthplace> “Quiet Surprise in the Prairie” <http://dbpedia.org/ontology/motto>
  62. 62. 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 )
  63. 63. 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
  64. 64. 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)
  65. 65. 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
  66. 66. 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
  67. 67. 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
  68. 68. 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
  69. 69. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology Information Service Engineering Lecture 6: 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) 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
  70. 70. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering - 1 Bibliography ● Tim Berners-Lee, James Hendler, Ora Lassila: The Semantic Web, Scientific American, 284(5), pp. 34-43(2001). ● S. Hitzler, S. Rudolph, Foundations of Semantic Web Technologies, Chapman / Hall, 2009.
  71. 71. Information Service Engineering , Prof. Dr. Harald Sack, FIZ Karlsruhe - Leibniz Institute for Information Infrastructure & AIFB - Karlsruhe Institute of Technology 3. Linked Data Engineering - 1 Syllabus Questions ● What is knowledge? ● How does knowledge representation work? ● What is an ontology? (Definition and Explanation) ● What are typical constituents of an ontology? ● What is the Semantic Web? ● What is the difference between URI and URL ● What’s the difference between identification and representation ? ● Explain HTTP Content Negotiation human readable and machine readable resources ● What is an RDF triple?

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