2 December 2005 
Web Information Systems 
Semantic Web 
Prof. Beat Signer 
Department of Computer Science 
Vrije Universit...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 2 
The Semantic Web 
I have a dream for...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 3 
The Semantic Web ... 
The Semantic W...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 4 
The Semantic Web ... 
 Meaning of d...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 5 
Video: The Future Internet
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 6 
Semantic Web Stack 
 The Semantic W...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 7 
Semantic Web Stack ... 
 XML Namesp...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 8 
Semantic Web Stack ... 
 Web Ontolo...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 9 
Semantic Web Stack ... 
 Unifying L...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 10 
Resource Description Framework 
 T...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 11 
Resource Description Framework ... ...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 12 
RDF Graph 
 A set of RDF statement...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 13 
RDF Graph ... 
 Anonymous resource...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 14 
RDF Reification 
 An RDF triple is...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 15 
RDF Container Nodes 
 Special cont...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 16 
Advantages of RDF 
 Simple 
 Enab...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 17 
RDF Schema (RDFS) 
 Vocabulary des...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 18 
RDF Schema Example 
Beat Signer 
ha...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 19 
Advantages of RDFS 
 With RDFS we ...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 20 
RDF(S) / XML Serialisation 
 Synta...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 21 
RDF Notation 3 (N3) 
 Short non-XM...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 22 
RDF Turtle Notation 
 Terse RDF Tr...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 23 
RDF Applications 
 Annotea project...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 24 
SPARQL Query Language 
 RDF query ...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 25 
Web Ontology Language (OWL) 
 OWL ...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 26 
Jena Semantic Web Framework 
 Open...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 27 
Protégé 
 Free open source platfor...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 28 
Swoogle 
 Search engine for seman-...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 29 
Friend of a Friend (FOAF) 
 Person...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 30 
Friend of a Friend (FOAF) ... 
 Fi...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 31 
Semantic Wikis 
 Use Semantic Web ...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 32 
Linked Data 
 Link different data ...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 33 
Semantic Desktops 
 Apply Semantic...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 34 
GoodRelations 
 Lightweight ontolo...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 35 
Microformats 
 Add semantics to (X...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 36 
hCard Microformat Example 
 Some s...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 37 
RDF in Attributes (RDFa) 
 Add a s...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 38 
Microdata 
 Add machine readable m...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 39 
Exercise 9 
 Semantic Web 
 worki...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 40 
References 
 Tim Berners-Lee, Jame...
November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 41 
References ... 
 Linked Data 
 ht...
2 December 2005 
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Semantic Web - Lecture 09 - Web Information Systems (4011474FNR)

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This lecture is part of a Web Information Systems course given at the Vrije Universiteit Brussel.

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Semantic Web - Lecture 09 - Web Information Systems (4011474FNR)

  1. 1. 2 December 2005 Web Information Systems Semantic Web Prof. Beat Signer Department of Computer Science Vrije Universiteit Brussel http://www.beatsigner.com
  2. 2. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 2 The Semantic Web I have a dream for the Web [in which com-puters] 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. The 'intelligent agents' people have touted for ages will finally materialize. Weaving the Web - The Original Design and Ultimate Destiny of the World Wide Web by Its Inventor, Tim Berners-Lee, Harper San Francisco, September 1999 Tim Berners-Lee
  3. 3. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 3 The Semantic Web ... The Semantic Web is a vision: the idea of having data on the Web defined and linked in a way that it can be used by machines not just for display purposes, but for auto-mation, integration and reuse of data across various applications. Metadata provides a means to make statements and create machine-readable statements. W3C, 2003
  4. 4. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 4 The Semantic Web ...  Meaning of data on the Web can not only be infered by people but also discovered by machines without (or with less) human intervention  Web of Data instead of Web of Documents  the Web as a huge decentralised database (knowledge base)  machine-accessible data  data may be interconnected similar to today's webpages  machine-readable metadata for existing web content  combination of data from different sources to derive new facts  machines (agents) may use logical reasoning to infer facts that are not explicitly recorded  Crucial component of Web 3.0 or Giant Global Graph
  5. 5. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 5 Video: The Future Internet
  6. 6. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 6 Semantic Web Stack  The Semantic Web Stack (or Semantic Web Cake) describes the architecture of the Semantic Web  URI/IRI - unique identification of semantic web resources  Unicode - representing/manipulating text in different languages  XML - interchange of structured data over the Web Character set: UNICODE Cryptography Syntax: XML and XML Namespaces Data interchange: RDF Taxonomies: RDFS Ontologies: Querying: OWL SPARQL Unifying Logic Trust User interface and applications Proof Rules: RIF/SWRL Based on [http://en.wikipedia.org/wiki/File:Semantic-web-stack.png] Identifiers: URI/IRI
  7. 7. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 7 Semantic Web Stack ...  XML Namespaces - uniquely qualify markup from multiple sources (integration)  Resource Description Framework (RDF) - define RDF triples and repre-sent resource information in a graph structure  RDF Schema (RDFS) - create hierarchies of classes and properties Character set: UNICODE Cryptography Syntax: XML and XML Namespaces Data interchange: RDF Taxonomies: RDFS Ontologies: Querying: OWL SPARQL Unifying Logic Trust User interface and applications Proof Rules: RIF/SWRL Based on [http://en.wikipedia.org/wiki/File:Semantic-web-stack.png] Identifiers: URI/IRI
  8. 8. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 8 Semantic Web Stack ...  Web Ontology Language (OWL) - language to define vocabularies - extends RDFS with more ad-vanced features (e.g. cardinality) - enables reasoning based on description logic  SPARQL - query language to query any RDF-based data  Rule Interchange Format (RIF) and Semantic Web Rule Language (SWRL) - describe relations that cannot be described in OWL Character set: UNICODE Cryptography Syntax: XML and XML Namespaces Data interchange: RDF Taxonomies: RDFS Ontologies: Querying: OWL SPARQL Unifying Logic Trust User interface and applications Proof Rules: RIF/SWRL Based on [http://en.wikipedia.org/wiki/File:Semantic-web-stack.png] Identifiers: URI/IRI
  9. 9. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 9 Semantic Web Stack ...  Unifying Logic - logical reasoning (infer new facts and check consistency)  Proof - explain logical reasoning steps  Cryptography - protect RDF data via encryption - validate the source of facts by digitally signing RDF data  Trust - authentification of sources and trustworthiness of derived facts  User Interface - user interfaces for semantic web applications Character set: UNICODE Cryptography Syntax: XML and XML Namespaces Data interchange: RDF Taxonomies: RDFS Ontologies: Querying: OWL SPARQL Unifying Logic Trust User interface and applications Proof Rules: RIF/SWRL Based on [http://en.wikipedia.org/wiki/File:Semantic-web-stack.png] Identifiers: URI/IRI
  10. 10. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 10 Resource Description Framework  The Resource Description Framework (RDF) has been designed to describe  data and metadata about specific subjects  structure of data sets  relationships between bits of data  An RDF statement (triple) consists of three parts  subject  predicate (property)  object (value) {person-1, name, "Niklaus Wirth"} subject predicate object
  11. 11. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 11 Resource Description Framework ...  Subjects, predicates and objects are all resources  Resource  anything that can be referenced by a URI  Literal  non-structured data (e.g. String, Integer, ...); is also a resource  a literal cannot be the subject of an RDF statement  Predicate  relation between two resources or between a resource and a literal  RDF data is often stored in relational databases or so-called triplestores (e.g. Apache Jena)  up to billions of triples
  12. 12. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 12 RDF Graph  A set of RDF statements can be represented as a directed labelled graph  note that in RDF we can only define statements about specific instances but not about generic concepts - ontologies have to be used to define statements about generic concepts Beat Signer hasFamilyName hasGivenName http://wise.vub.ac.be/beat-signer
  13. 13. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 13 RDF Graph ...  Anonymous resources have no explicit identifier  in the example, the "office" is an anonymous resource  anonymous resources are also called blank nodes or bnodes  blank nodes can only be used as subjects or objects Beat Signer hasGivenName hasFamilyName http://wise.vub.ac.be hasDirector http://wise.vub.ac.be/beat-signer isMember Lode http://wise.vub.ac.be/lode-hoste Hoste hasFamily Name hasGivenName isColleague hasOffice 10F733 026293306 room phone
  14. 14. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 14 RDF Reification  An RDF triple is not a resource and can therefore not become subject of another statement  we have to reify the original statement - make a resource out of the statement Beat Signer hasGivenName hasFamilyName http://wise.vub.ac.be hasDirector http://wise.vub.ac.be/beat/ isMember Lode http://wise.vub.ac.be/lode/ Hoste hasGivenName rdf:subject rdf:object rdf:statement isColleague rdf:type rdf:Property 1 forYears hasFamily Name
  15. 15. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 15 RDF Container Nodes  Special container resource types  bag - number of unordered resources with potential duplicates  sequence - ordered collection of resources  alternative - one of the members can be selected  collection - closed; once it has been defined, the members can no longer be changed http://wise.vub.ac.be/beat-signer wearsShirt http://shirt.org/shirt1 http://shirt.og/shirt2 RDF:_2 rdf:alternative
  16. 16. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 16 Advantages of RDF  Simple  Enables the combination (merging) of data from different data models  not easily possible in a relational database (different schemas)  The same resource can be annotated by different people  resource referenced by URI  separation of data and metadata  Well-defined standard  many tools available - triplestores, parsers, editors, frameworks, ...
  17. 17. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 17 RDF Schema (RDFS)  Vocabulary description language for RDF  domain vocabulary and structure  Define common concepts and relationships  classes (rdfs:Class) and subclasses (rdfs:subClassOf)  properties and sub-properties (rdfs:subPropertyOf)  domain (rdfs:domain) and range (rdfs:range) of a property  rdfs:seeAlso, rdfs:isDefinedBy (utility properties)  rdfs:label, rdfs:comment  ...  Provides the basic elements for the definition of ontologies
  18. 18. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 18 RDF Schema Example Beat Signer hasGivenName hasFamilyName Researcher http://wise.vub.ac.be/beat-signer Lode http://wise.vub.ac.be/lode-hoste Hoste isColleague hasGivenName hasFamilyName rdf:type rdf:type Person isColleague rdfs:Class rdf:Property rdf:type rdf:type rdfs:domain rdfs:range rdfs:subClassOf rdfs:Literal rdfs:Literal rdfs:Literal rdfs:Literal rdf:type rdf:type rdf:type rdf:type
  19. 19. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 19 Advantages of RDFS  With RDFS we have a richer expressiveness (e.g. subClassOf) than with RDF  Simple reasoning (e.g. type hierarchy)  Many existing tools to deal with RDFS  However, some things cannot be expressed; for example  "a person must have a family name"  "a person can have at most one family name" (cardinality)  "if Beat is a colleague of Lode then Lode is a colleague of Beat" (transitivity)  these issues are addressed by the Web Ontology Language (OWL)
  20. 20. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 20 RDF(S) / XML Serialisation  Syntax not so easy to learn  many different ways to construct the same statement  long URIs are hard to read {http://wise.vub.ac.be/beat-signer, isColleague, http://wise.vub.ac.be/lode-hoste} <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> <rdf:Description rdf:about="http://wise.vub.ac.be/beat-signer"> <isColleague rdf:resource="http://wise.vub.ac.be/lode-hoste"/> <hasGivenName>Beat</hasGivenName> ... </rdf:Description> ... </rdf:RDF>
  21. 21. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 21 RDF Notation 3 (N3)  Short non-XML serialisation  separate predicates with a semicollon  finish subject definition with a full stop  Note that the N3 notation offers more features than are necessary for RDF(S) serialisation  e.g. support for RDF-based rules <http://wise.vub.ac.be/beat-signer> isColleague <http://wise.vub.ac.be/lode-hoste>; ... hasGivenName "Beat".
  22. 22. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 22 RDF Turtle Notation  Terse RDF Triple Language  Subset of N3 language  only describes RDF features (RDF graph model)  Syntax looks similar to Notation 3  http://www.w3.org/TeamSubmission/turtle/  Many RDF frameworks (e.g. Jena) offer Turtle parser and serialisation features
  23. 23. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 23 RDF Applications  Annotea project  defines an RDF schema for the types of annotations that can be used to annote webpages  RSS  some RSS versions use RDF(S) / XML serialisation  Dublin Core  widely used to describe digital media (also in standard HTML) - bibliographic metadata such a title, creator, description, ...  uses RDF(S) / XML serialisation as one possible representation <head> ... <meta name="DC.Subject" content="Interactive Paper, Cross-media ..."/> <meta name="DC.Description" content="Beat Signer does research on ..."/> </head>
  24. 24. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 24 SPARQL Query Language  RDF query language which can be used to  extract information as URIs, literals, blank nodes or subgraphs  SPARQL SELECT queries return variable bindings  SPARQL querying relies on graph pattern matching  Example  get the name and mbox of all subjects that have both of these properties defined SELECT ?name ?mbox WHERE { ?x foaf:name ?name . ?x foaf:mbox ?mbox }
  25. 25. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 25 Web Ontology Language (OWL)  OWL evolved from DAML+OIL  DAML is the DARPA Agent Markup Language  OIL stands for Ontology Inference Layer  There exist 3 different OWL sublanguages (flavours) with different expressivness  OWL Full - maximum expressiveness (full language) - no computational guarantee  OWL DL - maximal OWL Full subset that is still computationally decidable  OWL Lite - classification hierarchy and simple constraints (limited cardinality constraints) - weakest of the three variants
  26. 26. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 26 Jena Semantic Web Framework  Open source Semantic Web framework for Java  create and access data from RDF graphs via an RDF API  offers an OWL API  data can be stored in files, databases or accessed via URLs  http://jena.sourceforge.net  RDF graphs can be serialised into different formats  RDF/XML  Notation 3  Turtle  relational database  SPARQL query interface  Multiple reasoners
  27. 27. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 27 Protégé  Free open source platform to create, manipulate and visualise ontologies  Two modelling tools  Protégé-Frames editor - build and populate frame-based ontologies - Java API for plug-ins  Protégé-OWL editor - build Semantic Web ontologies
  28. 28. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 28 Swoogle  Search engine for seman-tic web data (RDF)  ontologies  instance data  single terms  Ranking of semantic web documents  inspired by Google's PageRank  Developed at the University of Maryland  http://swoogle.umbc.edu
  29. 29. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 29 Friend of a Friend (FOAF)  Personal information and connections to friends in RDF  http://www.foaf-project.org <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:foaf="http://xmlns.com/foaf/0.1/"> <foaf:Person> <foaf:name>Beat Signer</foaf:name> <foaf:title>Prof.</foaf:title> <foaf:givenname>Beat</foaf:givenname> <foaf:family_name>Signer</foaf:family_name> <foaf:nick>Beat</foaf:nick> <foaf:mbox_sha1sum>ce6d419869307d57839feef6445a9d64f784eb36</foaf:mbox_sha1sum> ... <foaf:knows> <foaf:Person> <foaf:name>Moira C. Norrie</foaf:name> <foaf:mbox_sha1sum>4cb61b36a6feaa48c78acbb51fcce7cb356afdd6</foaf:mbox_sha1sum> <rdfs:seeAlso rdf:resource="http://www.globis.ethz.ch/people/norrie.rdf"> </foaf:Person> </foaf:knows> ... </foaf:Person> </rdf:RDF>
  30. 30. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 30 Friend of a Friend (FOAF) ...  First social Semantic Web application  Miller and Brickley, 2000  Describe a social network without a central database  links can be followed by spiders (data mining)  no unique identifier - identification by description (pedicates and objects)  "six degrees of separation" or "small world phenomenon"  FOAFNaut browser [http://rdfweb.org/images/foaf/foafnaut-screenshot-path.jpg]
  31. 31. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 31 Semantic Wikis  Use Semantic Web technologies to provide machine-processable Wiki content  page content  link metadata  Ontology reasoning  much richer query interface  Existing semantic Wikis  DBPedia  Semantic MediaWiki  ...
  32. 32. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 32 Linked Data  Link different data sources (URIs) on the Web  provide metadata about the resources via RDF/XML, N3, etc.  provide links to resources in other data sets on the Web  Linked Open Data community project  RDF tripes from DBPedia, GeneID, ACM, etc. (>30 billion triples)  links between those triples (>500 million links) http://lod-cloud.net/versions/2014-08-30/lod-cloud.svg
  33. 33. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 33 Semantic Desktops  Apply Semantic Web tech-nologies to personal infor-mation management (PIM)  inter-application data sharing  enhancement of limited filesystem functionality - add document metadata  Examples  Haystack  Nepomuk Nepomuk Integration with Dolphin (KDE 4.0)
  34. 34. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 34 GoodRelations  Lightweight ontology for expressing product information in e-commerce web applications  Product features  offers  prices  units  ...  Adopted by various companies  Yahoo  BestBuy  ...  Leads to enhanced product search functionality
  35. 35. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 35 Microformats  Add semantics to (X)HTML pages  Makes use of specific (X)HTML tag attributes  class and rel attributes - e.g. rel="nofollow" for search engines  Specific microformats  hCard: contact information  hCalendar: event information  hProduct: product information  Alternative solutions  semantic web (RDFa)  GRDDL - Gleaning Resource Descriptions from Dialects of Language - can convert from microformats to semantic web data (RDF)
  36. 36. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 36 hCard Microformat Example  Some search engines (e.g. Google and Yahoo) start to pay attention to different types of microformats <head profile="http://www.w3.org/2006/03/hcard"> ... </head> ... <div class="vcard"> <div class="fn">Lode Hoste</div> <div class="org">Vrije Universiteit Brussel</div> <div class="tel">32 2629 3306</div> <a class="url" href="http://wise.vub.ac.be/members/lode-hoste"> http://wise.vub.ac.be/members/lode-hoste</a> </div>
  37. 37. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 37 RDF in Attributes (RDFa)  Add a set of attribute extensions to XHTML for embedding RDF metadata  Different vocabularies  FOAF, video, audio, commerce, …  Search engines (e.g. Yahoo and Google) process certain RDFa metadata (e.g. product information) <p xmlns:dc=http://purl.org/dc/elements/1.1/ about="http://www.amazon.com/..."> and the will to live. <span property="dc:creator">Simpson</span> dedicates the book <cite property="dc:title">Touching the Void</cite> to the... The book was published in <span property="dc:date" content="1989-12-01">December 1989</span>. </p>
  38. 38. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 38 Microdata  Add machine readable metadata (semantics) to HTML5 documents in the form of key/value pairs  can be used by crawlers, search engines (SEO) and browsers to provide a richer browsing experience  alternative to Microformats and RDFa W3C Working Draft <section itemscope itemtype="http://data-vocabulary.org/Person"> Hello, my name is <span itemprop="name">Beat Signer</span> and I am a <span itemprop="title">Professor</span> at the <span itemprop="affiliation">Vrije Universiteit Brussel. </span> <section itemprop="address" itemscope itemtype="http://data -vocabulary.org/Address">My address is: <span itemprop="street-address">Pleinlaan 2</span>, <span itemprop="postal-code">1050 </span> <span itemprop="locality">Brussels</span>, <span itemprop="country-name">Belgium</span>. </section> </section>
  39. 39. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 39 Exercise 9  Semantic Web  working with linked data
  40. 40. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 40 References  Tim Berners-Lee, James Hendler and Ora Lassila, The Semantic Web, Scientific American Magazine, May 2001  http://www.scientificamerican.com/article.cfm?id=the-semantic- web  The Future Internet: Service Web 3.0  http://www.youtube.com/watch?v=off08As3siM  Resource Description Framework (RDF)  http://www.w3.org/RDF/  Thomas B. Passin, Explorer's Guide to the Semantic Web, Manning Publications, March 2004
  41. 41. November 28, 2014 Beat Signer - Department of Computer Science - bsigner@vub.ac.be 41 References ...  Linked Data  http://linkeddata.org
  42. 42. 2 December 2005 Next Lecture Web Search

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