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CS520 Web Programming Introduction to the Semantic Web

Learn about the Semantic Web, a vision where machines can analyze data on the web to handle day-to-day tasks and enable intelligent agents. Discover knowledge representation, intelligent agents, RDF, ontology, and OWL.

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CS520 Web Programming Introduction to the Semantic Web

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  1. CS520 Web ProgrammingIntroduction to the Semantic Web Chengyu Sun California State University, Los Angeles

  2. Tim Berners-Lee • Inventor of the WWW • Wrote the first web client (browser-editor) and server in 1990 • Chair of MIT CSAIL and director of World Wide Web Consortium (W3C)

  3. The Vision In the first part, the Web becomes a much more powerful means for collaboration between people. [...] In the second part of the dream, collaborations extend to computers. Machines become capable of analyzing all the data on the Web - the content, links, and transactions between people and computers. A "Semantic Web," which should make this possible, has yet to emerge, but when it does, the day-to-day mechanisms of trade, bureaucracy, and our daily lives will be handled by machines talking to machines, leaving humans to provide the inspiration and intuition. The intelligent "agents" people have touted for ages will finally materialize. This machine-understandable Web will come about through the Implementation of a series of technical advancements and social agreements that are now beginning (and which I describe in the next chapter). Weaving the Web, Tim Berners-Less, 2000

  4. The Example Prescribed treatment Doctor’s Office Lucy’s Agent Insurance plan Insurance Company Providers in plan Provider’s Listing Provider ratings Rating Services schedule Pete’s Agent Provider 1 schedule Provider 2 The Semantic Web, Berners-Lee et. al, 2001

  5. The Issues • Knowledge representation • Intelligent agent

  6. The Stack (2000 version)

  7. The Stack (2003 version)

  8. The Stack (2005 version)

  9. Resource Description Framework (RDF) • A language that describes resources, which essentially can be anything • RDF triple: <subject, predicate, object>

  10. RDF Example 1 Kobe Bryant plays for the Lakers. The official web site of the Lakers is http://www.nba.com/lakers. @prefix nba: <http://www.nba.com/ontology> <nba:Bryant> <nba:play-for> <nba:lakers> <nba:lakers> <nba:webaddr> “http://www.nba.com/laker” object subject predicate literal

  11. RDF Example 2 @prefix nba: <http://www.nba.com/ontology> @prefix mlb: <http://www.mlb.com/ontology> @prefix general: <http://www.w3c.org/ontology> <nba:lakers> <general:sport> <general:basketball> <nba:lakers> <general:location> <general:la> <mlb:yankees> <general:sport> <general:baseball> <mlb:yankees> <general:location> <general:ny>

  12. Merge and Reasoning bryant lakers basketball http://www.nba.com/lakers la

  13. Other Features • Containers • Bag, sequence, alternate • Statements can be made about either a collection or an individual element of the collection • Reification – making statements about statements • Statement as subject

  14. RDF/XML Serialization <rdf:RDF xmlns:nba="http://www.nba.com/ontology#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description rdf:about="http://www.nba.com/ontology#Bryant"> <nba:plays-for> <rdf:Description rdf:about='http://www.nba.com/ontology#Lakers"> <nba:webaddr rdf:resource="http://www.nba.com/lakers"/> </rdf:Description> </nba:plays-for> </rdf:Description> </rdf:RDF>

  15. RDF Adoption The Semantic Web, Daconta et. al, 2003

  16. Ontology • Description, representation, and classification concepts and their relationships • Vocabulary, taxonomy, thesaurus, database schema, UML diagram, logic …

  17. Dublin Core Metadata Initiative • http://dublincore.org/

  18. Open Directory Project • http://dmoz.org/

  19. UML Diagram

  20. So How to We Define an Ontology? • RDF Schema • OWL

  21. rdfs:Class rdfs:label rdfs:subclassOf rdfs:Property Rdfs:subPropertyof rdfs:domain rdfs:range rdfs:type rdfs:seeAlso rdfs:isDefinedBy rdfs:comment rdfs:Literal rdfs:XMLLiteral RDF Schema

  22. RDF Schema Example The Semantic Web, Daconta et. al, 2003

  23. OWL • Web Ontology Language (OWL) • OWL Full • OWL DL • OWL Lite

  24. owl:AllDifferent owl:Class owl:DataRange owl:DatatypeProperty owl:DeprecatedClass owl:DeprecatedProperty owl:FuncationalProperty owl:InverseFunctionalProperty owl:Nothing owl:ObjectProperty owl:Ontology owl:Restriction owl:SymmetricProperty owl:maxCardinality owl:minCardinality owl:oneOf owl:onProperty owl:priorVersion owl:sameAs owl:sameIndividualAs owl:someValuesFrom owl:subClassOf owl:TransitiveProperty owl:unionOf owl:versionInfo … Some OWL Elements

  25. References • The Semantic Web by Daconta, Obrst, and Smith, 2003. • Various presentations by Tim Berners-Lee - http://www.w3.org/People/Berners-Lee/

  26. The Other Side of the Story I'd rather make progress by having computers understand what humans write, than by forcing humans to write in ways that computers can understand. Sergey Brin at InfoWorld 2002 CTO Forum

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