1 / 45

An Introduction to the Semantic Web

An Introduction to the Semantic Web. Samad Paydar Web Technology Laboratory Computer Engineering Department Ferdowsi University of Mashhad 1389/11/20. Outline. Why Semantic Web? What is Semantic Web? Semantic Web Main Technologies Semantic Web Timeline. Semantic Web Scenario.

hayley
Télécharger la présentation

An Introduction to the Semantic Web

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An Introduction to the Semantic Web Samad Paydar Web Technology Laboratory Computer Engineering Department Ferdowsi University of Mashhad 1389/11/20

  2. Outline Why Semantic Web? What is Semantic Web? Semantic Web Main Technologies Semantic Web Timeline

  3. Semantic Web Scenario Physician’s Agent Mom required treatment Pete’ Agent Insurance Co. Rating Provider sites in-plan? close-by? Specialist? Schedule appointment Driving schedule Lucy’s Agent

  4. The Vision • The World Wide Web (the syntactic web) is a big and impressive success story, both in terms of • the amount of available information and • the growth rate of human users • It has entered most areas of our daily life and business.

  5. The Vision • This success is based on its simplicity • It’s easy to publish information on the web • It’s easy to access information (but if you know where they are)

  6. Why Semantic Web? • Tasks often require to combine data on the Web: • hotel and travel information may come from different sites • searches in different digital libraries • Humans combine these information easily even if • different terminologies are used • the information is incomplete, or buried in images, videos, … • But Machines?

  7. What is the Problem?

  8. Challenge • Query • What is the name of a person who is a member of an organization in Iran, and likes a kind of sport?

  9. Why Semantic Web? • (Some) data should be available for machines for further processing • Metadata: Data about data • Data should be possibly combined, merged on a Web scale • Machines may also need to reason about that data

  10. What is Semantic Web? • Tim Berners-Lee: • “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.” 2001

  11. Semantic Web “The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents roaming from page to page can readily carry out sophisticated tasks for users” 2001

  12. Current Web

  13. Current Web • Resources • identified by URI's • untyped • Links • href, src, ... • limited, non-descriptive • User • Exciting world - semantics of the resource, however, gleaned from content • Machine: • Very little information available - significance of the links only evident from the context around the anchor.

  14. Semantic Web

  15. Semantic Web • Resources • Globally Identified by URI's • or Locally scoped (Blank) • Extensible • Relational • Links • Identified by URI's • Extensible • Relational • User • Even more exciting world, richer user experience • Machine • More processable information is available (Data Web) • Computers and people • Work, learn and exchange knowledge effectively

  16. Semantic Web Technologies The Semantic Web extends the Web through the use of standards, markup languages and related processing tools

  17. Semantic Web Layer Cake

  18. A Simple Web Page • Markup consists of: • rendering information (e.g., font size and colour) • Hyper-links to related content • Semantic content is accessible to humans but not (easily) to computers…

  19. Challenge • Query • What is the name of a person who is a member of an organization in Iran, and likes a kind of sport?

  20. What information can we see… Hi! My name is Ali! This is my homepage. I am a student at Ferdowsi University of Mashhad. I like football.

  21. The Page Source Code in HTML <html> <head> <title>Ali's Homepage </title></head> <body> <p><b>Hi!</b></p> <p><b>My name is Ali!</b></p> </b> <p>This is my homepage. I am a student at <a href=“http://um.ac.ir">Ferdowsi University of Mashhad</a>.</p> <p>I like football.</p> </body> </html>

  22. What information can a machine see… <html> <head> <title>…………………..</title></head> <body> <p><b>………</b></p> <p><b>....................</b></p> </b> <p>…………………………………………..……<a href=“………………”>…………………..</a>.</p> <p>............................</p> </body> </html>

  23. XML XML allows users to add arbitrary structure to their documents but says nothing about what the structures mean

  24. Solution: XML “meaningful” tags …………………………. <student>………………….</student> <university>……………………..<university>…………………………………………………………………………………………………….

  25. But What if? …………………………. <boy>………………….</boy> <college>……………………..<college>…………………………………………………………………………………………………….

  26. RDF • Resource Description Framework • A data model • Meaning encoded in sets of ‘triples’: entities have properties which have values • Each triple: subject-predicate-object • Entities, properties and values all have distinct URIs

  27. RDF Ali http://um.ac.ir Ferdowsi University of Mashhad studentOF hasHomePage

  28. RDF <rdf:Descriptionabout="some.uri/person/ali"> <studentOfresource="some.uri/Ferdowsi_University_of_Mashhad"/> </Description> <Description about="Ferdowsi_University_of_Mashhad"> <hasHomePage>http://um.ac.ir</hasHomePage> </rdf:Description>

  29. Challenge • Query • What is the name of a person who is a member of an organization in Iran, and likes a kind of sport?

  30. But… • What is the relation between • a Student and a Person? • Football and Sport? • University and College? • University and Website? • Ontology is the solution

  31. Ontology • Ontologies provide semantic • Main elements of an ontology: • Concepts • Relationships • Hierarchical • Logical • Properties • Instances (individuals)

  32. Challenge • Query • What is the name of a person who is a member of an organization in Iran, and likes a kind of sport?

  33. Ontology • To answer the query it is required to tell the machine that • There is a class of objects named ‘Student’ • There is a class of objects named ‘Person’ • Each Student is a Person • Each Person has a Name • There is a class of objects named ‘Sport Type’ • Football is a kind of Sport • There is an instance of a Student that its Name is “Ali” • ….

  34. Ontology • Ontology Languages • OWL • RDFS (RDF Schema) • SHOE • DAML+OIL

  35. Scientific American, May 2001 Realising the complete “vision” is too hard for now (probably) But we can make a start by adding semantic annotation to web resources

  36. Don’t Forget! 1895 2006

  37. Semantic Web Layer Cake

  38. Semantic Web: Now • Numerous web technologies, languages, formats, and standards which provide the inferastructure • URI, XML, XML Schema, RDF, RDFS, OWL, SPARQL, SerQL, HTTP, Microformats, RDFa,

  39. Semantic Web: Now • A large body of research and activity is related to ontologies, since they play a main role • Ontology engineering issues and tools • ontology development, ontology selection, ontology matching, ontology evaluation, ontology partitioning,…. • Numerous Ontologies are developed in different domains, e.g. FOAF, DOAP, SIOC, SKOS, …

  40. Semantic Web: Now • Semantic Web technologies are used as an enabler in different areas to develop small semantic web applications • Ontology-based ….. • Ontology-enabled … • Semantic-Web-Enabled … • Semantic ….

  41. Semantic Web Application Areas Content Discovery Content Management Customization and Adaptation Data Integration Domain Modeling Search and Information Retrieval Social Networks Automating Tasks Knowledge Management

  42. Semantic Web: Now • Semantic Web Search Engines • Swoogle, SWSE, Watson, Sindice, Falcons, Yahoo! Microsearch, ….

  43. Web Evolution Timeline

  44. Linked Data • If we see Semantic Web as a long term goal then Linked Data is a major step towards it’s large scale and full-featured realization

  45. Thanks!! Any Question?

More Related