Wissenstechnologie WS 08/09



                        Michael Granitzer
           IWM TU Graz & Know-Center
            ...
Today



           Topics of the practical excercise




           Overview Semantic Web (Rep)


           The Semantic...
Organization – Practical Excercise

 Practical/technical or theoretical working out of particular topics in groups
    of ...
Organization – Scheduling


Milestone    Theoretical           Technical             How?
             Exercise           ...
Excercise Topics                                               Topics of the practical

 Schriftlich theoretische A b it
 ...
Exercise Topics                                      Topics of the practical

 S h iftli h th    ti h A b it
 Schriftlich ...
Excercise Topics                                       Topics of the practical

P kti h technische Arbeiten
Praktische t h...
Excercise Topics
Praktische technische Arbeiten

   Yahoo Answers: Corpus Mining, Goal Extraction and Goal
               ...
Exercise Topics                                          Topics of the practical

P   ti l/t h i l         i
Practical/tec...
Exercise Topics                                      Topics of the practical
                                             ...
Questions




                                                                  11
                                       ...
The digital world (wide web) today                                                         Overview
                      ...
Intelligent Web = Semantic Web + Social Web
Web 3 0 = Semantic Web + Web 2 0 ;)
    3.0                      2.0

•   Sema...
Search in the WWW                                  Overview

An example                                         Semantic W...
The Problem of Relationships                         Overview
                                                     Semanti...
Definition „Semantic Web“                               Overview
                                                        S...
The Vision as Application Scenario                         Overview
                                                      ...
Foundations of the Semantic Web                       Overview
                                                      Seman...
Foundations of the Semantic Web                  Overview
                                                 Semantic Web

F...
Foundations of the Semantic Web                  Overview
                                                 Semantic Web

…...
The Semantic Web Stack



How to Express Semantics
A small example

 John Lennon
                                      Is ...
The Semantic Web Stack



Semantic Web Stack




   a.k.a. SW Layer Cake
               y
   a.k.a. SW Tower




         ...
The Semantic Web Stack



Semantic Web Stack – the original one




                                                      ...
The Semantic Web Stack



Semantic Web Stack




   Unicode
   URI




                                                   ...
The Semantic Web Stack




Uniform Ressource Identifier (URI)


   The Who ?=? Who
   Decentrality requires unique identif...
The Semantic Web Stack



Uniform Ressource Identifier (URI)
Examples




   http://ftp.is.co.za/rfc/rfc1808.txt
   mailto...
The Semantic Web Stack



Unicode



   Universal Character Set
   International Industry Standard
                       ...
The Semantic Web Stack



Semantic Web Stack



   XML
   XML Schema
   Namespaces




                                   ...
The Semantic Web Stack



XML


   XML structured storage and serialisation of data
   Representation of the logical struc...
The Semantic Web Stack


XML
Example

   <?xml version=quot;1.0quot; encoding=quot;UTF-8quot; ?>
   <Person>
       <name>...
The Semantic Web Stack



XML Schema Languages



   Define the structure of an XML Document
      DTD (Document Type Defi...
The Semantic Web Stack



XML Schemasprachen - DTD



 <?xml version=quot;1.0quot;?>
 <note>
  <to>Tove</to>
  <from>Jani<...
The Semantic Web Stack




XML Schemasprachen - XML Schema


 <?xml version=quot;1.0quot;?>
 <note> <to>Tove</to> <from>Ja...
The Semantic Web Stack



Namespaces



   Equal tag names in a different context
    <note>                              ...
The Semantic Web Stack


Namespaces
Example


    <Buch   xmlns     = „http://exmple.com/“
            xmlns:per =
      „...
The Semantic Web Stack



Drawbacks of XML




                                                                 36
       ...
The Semantic Web Stack



Drawbacks of XML


   No semantic/meaning of tags




   Tree-like structure makes it hard to co...
The Semantic Web Stack



Semantic Web Stack




   RDF




                                                              ...
The Semantic Web Stack




RDF - Resource Description Framework

RDF is like my eccentric old uncle I don't know him as we...
The Semantic Web Stack



Goal of RDF


   Description of (Web) resource via metadata
   Historically focused on web sites...
The Semantic Web Stack



Application Examples Today


       1.0:                           2.0)
   RSS 1 0: RDF Site Sum...
The Semantic Web Stack



Classical Metadata


Classical Metadata are mostly key/value pairs:
    Resource: http://www.kno...
The Semantic Web Stack



RDF Basics


   Resources R
       Resources are represented as URI
       All things with an va...
The Semantic Web Stack



RDF Statement (Triples)


  Statement := <Subject Predicate Object>
               <Subject, Pre...
The Semantic Web Stack



RDF Statements (Triples)
A small example

     http://en.wikipedia.org/wiki/John_Lennon
     htt...
The Semantic Web Stack


RDF URI
How to make a URI unique?


                           ,j
   No technical enforcement, ju...
The Semantic Web Stack


RDF – Serialisation
RDF/XML

      /                               g
   RDF/XML serialises RDF Mo...
The Semantic Web Stack

RDF – Serialisation
RDF/XML Example


<?xml version=quot;1.0quot;?>
<rdf:RDF xmlns:rdf=quot;http:/...
The Semantic Web Stack


RDF – Serialisation
RDF/XML-ABBREV


   Abbrevations for some constructs in RDF/XML
       e.g. m...
The Semantic Web Stack


RDF – Serialisation
RDF/XML-ABBREV Example


<?xml version=quot;1.0quot;?>
<rdf:RDF xmlns:rdf=quo...
The Semantic Web Stack


RDF – Serialisation
RDF/XML Pros & Cons

   ++: Use Standardized serialisation format
   ~~: RDF ...
The Semantic Web Stack


RDF – Serialisation
N3 – Notation 3 N-Triples, Turtle
              3, N-Triples

               ...
The Semantic Web Stack


RDF – Serialisation
N3 – Notation 3 N-Triples, Turtle
              3, N-Triples




            ...
The Semantic Web Stack


RDF – Serialisation
N-Triples/Turtle Example

<http://www.example.org/index.html>
     <http://pu...
The Semantic Web Stack


RDF – Serialisation
Turtle Example - Extended

# Define some namespaces
@prefix rdf: <http://www....
The Semantic Web Stack


RDF Extended Concepts
Blank Nodes/ n-ary Relationships

   Example: „Pasta consists of 400g noodl...
The Semantic Web Stack


RDF Extended Concepts
Blank Nodes/ n-ary Relationships

   Insertion of a „structure“ Node
      ...
The Semantic Web Stack


RDF Extended Concepts
Blank Nodes/ n-ary Relationships

   No URI‘s required for such nodes
     ...
The Semantic Web Stack


RDF Extended Concepts
Container

   Use Blank nodes to group different kinds of sets and lists
  ...
The Semantic Web Stack


RDF Extended Concepts
Reification

   Making Statements over Statements

   „The detective assume...
The Semantic Web Stack


RDF Extended Concepts
Reification

                         „rdf:type
    Representation using „r...
The Semantic Web Stack



Summary RDF


   An abstract model for representing metadata
      Standardisation for exchangin...
Points you should take away from this
lecture

   What is the Semantic Web Stack?
   What are the restrictions of XML and ...
Outlook


                   Thursday, 16.10.08,
   Next Lecture on Thursday 16 10 08 10:15


               The Semantic ...
That‘s it for today…



Thanks for your attention


Questions/comments?


mgranitzer@tugraz.at
     i    @




           ...
License


   This work is licensed under the Creative Commons
   Attribution 2.0 Austria License.
   To view a copy of thi...
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Wissenstechnologie Ii 08 09.Voll

  1. 1. Wissenstechnologie WS 08/09 Michael Granitzer IWM TU Graz & Know-Center Know Center http://kmi tugraz at http://kmi.tugraz.at http://www.know-center.at http://www know center at This work is licensed under the Creative Commons Attribution 2.0 Austria License. To view a copy of this license, visit http://creativecommons.org/licenses/by/2.0/at/.
  2. 2. Today Topics of the practical excercise Overview Semantic Web (Rep) The Semantic Web Stack • U i d URI Unicode, • XML, XML Schema, Namespaces • Resource Description Framework 2 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  3. 3. Organization – Practical Excercise Practical/technical or theoretical working out of particular topics in groups of 2-4 f Announced also on the blog http://kmi.tugraz.at/blogs/wissenstechnologie/ubungsthemen/ Passwort: wt08 Details: http://kmi.tugraz.at/blogs/wissenstechnologie/prufungsmodus/ Practical/technical Exercise act ca /tec ca e c se – Documentation (10%) – Implementation (45%) – Presentation 8.01. or 11.12. (45%) Theoretical Excercise – Literature Gathering (Bibsonomy) (10%). – Written Summary (3500 words per group member) (45%) – Presentation 8.01. or 11.12. (45%) 3 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  4. 4. Organization – Scheduling Milestone Theoretical Technical How? Exercise Exercise Next Week Topic presentation In the lecture/ on (8.10.08) the blog 22.10.08 Topic selection and group via E-Mail to me announcement 24.11.08 Gathering of Requirements Bibsonomy/ Google relevant Literature Definition finished Docs finished 11 12 08 & 11.12.08 Oral t ti O l presentation O l presentation Oral t ti 08.01.09 of results & of results & feedback from my feedback from my side side 29.01.09 Delivery of final Delivery of final Via Google Docs results results 4 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  5. 5. Excercise Topics Topics of the practical Schriftlich theoretische A b it S h iftli h th ti h Arbeiten excercise 1. Überblick über Ontology Alignment und Ontology Matching Methoden 2. Eigenschaften, Indexstrukturen und erfolgreiche Anwendung von RDF Triple Stores 3. Semantische Suchmaschinen im Ü Überblick 4. Viral Marketing: Ausnutzung von Netzwerkeffekten im Marketing 5. 5 Suchtechniken für Blogs und Folksonomies 6. Überblick und Anwendung von visuellen SPARQL Query Schnittstellen und Abfragemethoden 7. Visualisierung und Navigation von RDF Grapen 8. Ein Vergleich von RDF Crawling mit Web Crawling Ansätzen mit Überblick über existierende Open Source Lösungen 9. Ansätze zur Inhaltsextraktion auf Blog-Seiten 5 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  6. 6. Exercise Topics Topics of the practical S h iftli h th ti h A b it Schriftlich theoretische Arbeiten excercise Key Questions for the theoretical topics What are the central question you want to address? Wh t is th borderline t other topics? What i the b d li to th t i ? What properties are important and how do they differentiate to other methods/tools/software? What are the hard problems on the issue and what are the problems already solved? What are successful and unsuccessful practical examples? p 6 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  7. 7. Excercise Topics Topics of the practical P kti h technische Arbeiten Praktische t h i h A b it excercise Programm JavaDoc2RDF: Extraktion von Wissen aus Programm- Code. Semantik Web Service Komposition p Sesame SAIL Layers für HBASE Experiment zur automatischen Kontexterkennung Erstellung von Ontologien basierend auf tags aus einer Web 2.0 Anwendung 20 Erstellung eines semantischen Media-Wikis und entsprechender Ontologie zur Unterstützung der p g g Vorlesung Wissenstechnolgien Ontology-based DBPedia browser 7 (Größere Gruppe bevorzugt) http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  8. 8. Excercise Topics Praktische technische Arbeiten Yahoo Answers: Corpus Mining, Goal Extraction and Goal Mining Graph Construction Twitter: Corpus Mining and Goal Extraction, and Goal p g , Graph Construction Goal-Oriented Web Applications: Using a GOAL-REST API 8 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  9. 9. Exercise Topics Topics of the practical P ti l/t h i l i Practical/technical exercise excercise Ask your advisor if you have any problems/questions Develop a requirements definition and software architecture. Define the goal of your work? Sketch your solution/approach Think of how to measure your results Narrow it down so that you think it is feasible Implementation: If possible use Java Keep it simple! Documentation using Google Docs and JavaDoc 9 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  10. 10. Exercise Topics Topics of the practical excercise Tutor: Thomas Stoppacher t.stoppacher at student.tugraz.at 10 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  11. 11. Questions 11 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  12. 12. The digital world (wide web) today Overview Semantic Web It’s size (R ) (Rep) Information growth per year (including print, film, optical etc.) Wachstum 1000 999 900 800 700 600 xabytes 500 Ex 400 300 200 100 5 160 It s It’s huge! 0 1998 1,6 2000 2002 2004 2006 2008 2010 2012 It grows Jahr fast! 12 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  13. 13. Intelligent Web = Semantic Web + Social Web Web 3 0 = Semantic Web + Web 2 0 ;) 3.0 2.0 • Semantic Wave Report. (http://www.readwriteweb.com/archives/semantic_wave_2008_free_report.php) (http://www readwriteweb com/archives/semantic wave 2008 free report php) 13 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  14. 14. Search in the WWW Overview An example Semantic Web (R ) (Rep) Image search for „Apache“ 14 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  15. 15. The Problem of Relationships Overview Semantic Web (Rep) (R ) No Meaning of Realtionships Who tried to shoot Mr. Burns in „Who shot Mr. Burns? Part 1“ ( (6. Season)) 15 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  16. 16. Definition „Semantic Web“ Overview Semantic Web (Rep) (R ) The Semantic Web is an extension of the current Web in which information is given well-defined meaning, better enbaling computers and people to work in cooperations. [Berners-Lee et al. 2001] http://www.sciam.com/print_version.cfm?articleID=00048144- 10D2 1C70 84A9809EC588EF21 10D2-1C70-84A9809EC588EF21 16 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  17. 17. The Vision as Application Scenario Overview Semantic Web (R ) (Rep) Plan a trip via the internet using your personal agent Agent searches automatically for Suitable flight Suitable hotels Alternative routes Also, the software agent tells you why it made this decision! 17 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  18. 18. Foundations of the Semantic Web Overview Semantic Web (R ) (Rep) Web of Data Decentral Management of Information Integration of heterogeneous information Standardized exchange of information between systems Not only the bits but also the meaning! bits, 18 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  19. 19. Foundations of the Semantic Web Overview Semantic Web From HTML… (R ) (Rep) 19 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  20. 20. Foundations of the Semantic Web Overview Semantic Web …to RDF (and further) (R ) (Rep) 20 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  21. 21. The Semantic Web Stack How to Express Semantics A small example John Lennon Is A Is Member Band The B tl Th Beatles Is Member Paul McCartney Founded in Is born in Query: all bands from England Ist in Liverpool England ?All bands with English artists? Inferenz & Reasoning: 21 English i P h i E li h artists := Person who is an artist and born in England i db i E l d http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  22. 22. The Semantic Web Stack Semantic Web Stack a.k.a. SW Layer Cake y a.k.a. SW Tower 22 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  23. 23. The Semantic Web Stack Semantic Web Stack – the original one 23 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  24. 24. The Semantic Web Stack Semantic Web Stack Unicode URI 24 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  25. 25. The Semantic Web Stack Uniform Ressource Identifier (URI) The Who ?=? Who Decentrality requires unique identification of resources, concepts etc. URI: Standard for Identification of Resources RFC 3986 - Uniform Resource Identifier (URI) Generalisation of URL‘s (e.g. http://) and URN‘s (e.g. ISBN) Resources in the Semantic Web are identified via URI‘s 25 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  26. 26. The Semantic Web Stack Uniform Ressource Identifier (URI) Examples http://ftp.is.co.za/rfc/rfc1808.txt mailto:NoOne.Nobody@example.com y@ p http://dbpedia.org/resource/Paul_McCartney http://bio2rdf.org/protein:123790407 26 http://www.w3.org/Addressing/ http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  27. 27. The Semantic Web Stack Unicode Universal Character Set International Industry Standard y Encoding Standard for text and URIs in the (Semantic) Web Combines different character set like (Arabian, Latin, Japan, Cyrillic etc.) http://www.unicode.org/ http://www.unicode.org/charts/ p // g/ / 27 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  28. 28. The Semantic Web Stack Semantic Web Stack XML XML Schema Namespaces 28 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  29. 29. The Semantic Web Stack XML XML structured storage and serialisation of data Representation of the logical structure of documents Tree-based Representation: Tags (Opening & Closing) for structuring Attributes for specifying properties Att ib tes fo specif ing p ope ties of Tags Entities as abbrevations (e.g. &quot;) Language independent acess via SAX (Simple API for XML, event-based) and DOM (Document Object Model, tree based) Automatic determination of well formed XML 29 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  30. 30. The Semantic Web Stack XML Example <?xml version=quot;1.0quot; encoding=quot;UTF-8quot; ?> <Person> <name>Michael Granitzer </name> <title>Dr.</title> <lecture> <name>Wissenstechnologien</name> <number>702.111</number> </lecture> </Person> <?xml version=quot;1.0quot; encoding=quot;UTF-8quot; ? ? l i quot;1 0quot; di quot;UTF 8quot; ?> <Person name=´Michael Granitzer´ title=´Dr.´> <lecture name=´Wissenstechnologien´ number=´702.111´/> </Person> http://www.w3.org/DOM/ http://www.saxproject.org/ Both are syntactically correct, which means well formed But is the structure correct? 30 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  31. 31. The Semantic Web Stack XML Schema Languages Define the structure of an XML Document DTD (Document Type Definition) XML Schema Define D fi What tag are following which tags Optional and required attributes Data type of an attribute/element XML Document is valid, if it meets the schema 31 http://www.w3.org/XML/Schema http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  32. 32. The Semantic Web Stack XML Schemasprachen - DTD <?xml version=quot;1.0quot;?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note> <!ELEMENT note ( ! (to, f from, h di heading, b d ) body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)> 32 http://www.w3schools.com/schema/schema_howto.asp http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  33. 33. The Semantic Web Stack XML Schemasprachen - XML Schema <?xml version=quot;1.0quot;?> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note> <?xml version=quot;1.0quot;?> <xs:schema xmlns:xs=quot;http://www.w3.org/2001/XMLSchemaquot;> <xs:element name=quot;notequot;> l quot; quot; <xs:complexType> <xs:sequence> <xs:element name=quot;toquot; type=quot;xs:stringquot;/> <xs:element name=quot;fromquot; type=quot;xs:stringquot;/> s:e e e t a e o type s:st g / <xs:element name=quot;headingquot; type=quot;xs:stringquot;/> <xs:element name=quot;bodyquot; type=quot;xs:stringquot;/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> 33 http://www.w3schools.com/schema/schema_howto.asp htt // 3 h l / h / h h t http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  34. 34. The Semantic Web Stack Namespaces Equal tag names in a different context <note> <animal> <to>Tove</to> <gender>M</gender> <from>Jani</from> <body> <heading>Reminder</heading> <legs>4</legs> … <body>Don't forget </body> me this weekend!</body> </animal> </note> / Namespaces can be specified per element <Element-Name xmlns[:prefix]=uri> Valid within the element http://www.w3.org/TR/REC-xml-names/ 34 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  35. 35. The Semantic Web Stack Namespaces Example <Buch xmlns = „http://exmple.com/“ xmlns:per = „http://personschema.org/“> „ p p g <Title> My Book</Title> <per:Autor name = „John Nobody“> p y <per:Title>Dr.</per:Title> </Buch> 35 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  36. 36. The Semantic Web Stack Drawbacks of XML 36 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  37. 37. The Semantic Web Stack Drawbacks of XML No semantic/meaning of tags Tree-like structure makes it hard to combine decentral stored information <Person> <lecture> <name> x</name> <name> x</name> / <lecture> <Person> … … </lecture> </Person> / </Person> </lecture> 37 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  38. 38. The Semantic Web Stack Semantic Web Stack RDF 38 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  39. 39. The Semantic Web Stack RDF - Resource Description Framework RDF is like my eccentric old uncle I don't know him as well uncle. don t as I'd like, which is partly his fault, since his eccentricities can be off-putting. Of course they're what make him so interesting and are the reason I want to get to know him better in the first place. [Kendall Grant Clark 2002] http://www.xml.com/pub/a/2002/11/13/deviant.html 39 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  40. 40. The Semantic Web Stack Goal of RDF Description of (Web) resource via metadata Historically focused on web sites E t d d t „general“ resources Extended to l“ For Classification of resources Classification of relationships between resources Unambigious description 40 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  41. 41. The Semantic Web Stack Application Examples Today 1.0: 2.0) RSS 1 0: RDF Site Summary (not RSS 2 0) Dublin Core Metadata Standard Ad b XMP f embedding objects Adobe for b ddi bj t Simple Knowledge Organisation Scheme (SKOS) DBPedia …. 41 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  42. 42. The Semantic Web Stack Classical Metadata Classical Metadata are mostly key/value pairs: Resource: http://www.know-center.at/xyz.ppt Type: PowerPoint Presentation yp Author: Michael Granitzer Topic: RDF In XML (Example): <presentation src='http://www.know-center.at/xyz.ppt'> <author> Michael Granitzer</author> <topic>RDF</topic> </presentation> 42 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  43. 43. The Semantic Web Stack RDF Basics Resources R Resources are represented as URI All things with an valid URI can be seen as resource Literals L Data values (e.g. String, Number etc.) Language of a literal Properties P Connecting resources Connecting resourcs with literals Identified via URI‘s URI s Combined into statements 43 http://www.w3.org/TR/rdf-concepts/ p // g/ / p / http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  44. 44. The Semantic Web Stack RDF Statement (Triples) Statement := <Subject Predicate Object> <Subject, Predicate, [Michael Granitzer, is author of, Presentation XYZ] Michael Granitzer … Subject is author of … Predicate Presentation XYZ … Object Michael Is author of Presentati Granitzer on XYZ 44 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  45. 45. The Semantic Web Stack RDF Statements (Triples) A small example http://en.wikipedia.org/wiki/John_Lennon htt // iki di / iki/J h L http://dbpedia.org/property/associatedActs http://dbpedia org/property/associatedActs http://en.wikipedia.org/wiki/The_Beatles http://en.wikipedia.org/wiki/Paul_McCartney http://dbpedia.org/property/associatedActs rdfs:label „Paul McCartney“ Subject j Predicate Object j http://en.wikipedia.org/wiki/J http://dbpedia.org/property/a http://en.wikipedia.org/wiki/T ohn_Lennon ssociatedActs he_Beatles http://en.wikipedia.org/wiki/P http://dbpedia.org/property/a http://en.wikipedia.org/wiki/T aul_McCartney ssociatedActs he_Beatles http://en.wikipedia.org/wiki/P Rdfs:label “Paul McCartney” 45 aul_McCartney http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  46. 46. The Semantic Web Stack RDF URI How to make a URI unique? ,j No technical enforcement, just recommendations from W3C Specialised Vocabulary Phone Numbers (e.g. tel://+43-316-873-9263) http://www.rfc-editor.org/rfc/rfc3966.txt http://www.rfc editor.org/rfc/rfc3966.txt ISBN Numbers Friend of a Friend Creating your own URI‘s (Recommendation Use a domain you control: http://www.know-center.at/ URI s URI‘s may not exist Be carefull with the semantic: – „Shakespear“ is author of „http://de.wikipedia.org/wiki/Othello“ „ p „ p p g – „Shakespear“ is author of „http://de.wikipedia.org/wiki/Othello#URI“ 46 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  47. 47. The Semantic Web Stack RDF – Serialisation RDF/XML / g RDF/XML serialises RDF Modells using XML Enclosing tags for RDF/XML : <rdf:RDF></rdf:RDF> Everything between is the RDF data model Statements describing resources are enclosed with <rdf:Description></rdf:Description> tags Reference to the resource via about=„URI“ attribut about „URI Properties of a resource as enclosing tag after rdf:Description http://www.w3.org/TR/rdf-syntax-grammar/ http://www.w3.org/RDF/Validator/ 47 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  48. 48. The Semantic Web Stack RDF – Serialisation RDF/XML Example <?xml version=quot;1.0quot;?> <rdf:RDF xmlns:rdf=quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#quot; xmlns:dc http://purl.org/dc/elements/1.1/ xmlns:dc=quot;http://purl org/dc/elements/1 1/quot; xmlns:ex=quot;http://example.org/terms/quot;> <rdf:Description rdf:about=quot;http://www.example.org/index.htmlquot;> <dc:creator rdf:resource=quot;http://www example org/staffid/85740quot; /> rdf:resource=quot;http://www.example.org/staffid/85740quot; </rdf:Description> <rdf:Description rdf:about=quot;http://www.example.org/staffid/85740quot; ex:name=quot;John S i hquot; / quot; h Smithquot; /> <rdf:Description rdf:about=quot;http://www.example.org/staffid/85740quot; ex:age=quot;27quot; /> </rdf:RDF> 48 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  49. 49. The Semantic Web Stack RDF – Serialisation RDF/XML-ABBREV Abbrevations for some constructs in RDF/XML e.g. more than one property for one resource within one <rdf:Description></rdf:Description> tag Shorter serialisation is inteded May not be the case for every graph Readability may not increase Name RDF/XML-ABBREV comes from the Jena Semantic Web Framework http://www.w3.org/TR/rdf-syntax-grammar/ http://www.w3.org/TR/2004/REC-rdf-primer-20040210/ 49 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  50. 50. The Semantic Web Stack RDF – Serialisation RDF/XML-ABBREV Example <?xml version=quot;1.0quot;?> <rdf:RDF xmlns:rdf=quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#quot; xmlns:dc http://purl.org/dc/elements/1.1/ xmlns:dc=quot;http://purl org/dc/elements/1 1/quot; xmlns:ex=quot;http://example.org/terms/quot;> <rdf:Description rdf:about=quot;http://www.example.org/index.htmlquot;> <dc:creator> <rdf:Description rdf:about=quot;http://www.example.org/staffid/85740quot; ex:name=quot;John Smithquot; ex:age=quot;27quot; / quot;27quot; /> </dc:creator> </rdf:Description> </rdf:RDF> 50 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  51. 51. The Semantic Web Stack RDF – Serialisation RDF/XML Pros & Cons ++: Use Standardized serialisation format ~~: RDF requires namespaces: no „:“ in attribute names <rdf:Description rdf:about=quot;http://www.example.org/index.htmlquot;> <rdf:Description http://www.w3.org/1999/02/22-rdf-syntax- ns#about=quot;http://www.example.org/index.htmlquot;> --: No „-“ after a „:“ in tag names <alter:-100> --: Namespaces not usable in attributes <rdf:RDF xmlns:rdf=quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#quot; xmlns:ex = „http://www.example.org/“> l htt // l /“ <rdf:Description rdf:about=„ex:index.htmlquot;> Different notations for equal URI‘s Very complex and hard to read for humans 51 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  52. 52. The Semantic Web Stack RDF – Serialisation N3 – Notation 3 N-Triples, Turtle 3, N-Triples Berners Lee Notation 3 1998 introduced by Tim Berners-Lee Write RDF Graph as set of triples – For each subject write all predicate object pairs separated by „;“ „; – Last predicatge-object pair ends with „.“ – <URI> and # indicate comments Contained also Path‘s and Rules Simpler Version: N-Triples as subset of N3 Extended after 2004 Turtle http://www.w3.org/DesignIssues/Notation3.html http://www.w3.org/2001/sw/RDFCore/ntriples/ http://www.dajobe.org/2004/01/turtle/ 52 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  53. 53. The Semantic Web Stack RDF – Serialisation N3 – Notation 3 N-Triples, Turtle 3, N-Triples See http://www.w3.org/Desi gnIssues/Notation3.html 53 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  54. 54. The Semantic Web Stack RDF – Serialisation N-Triples/Turtle Example <http://www.example.org/index.html> <http://purl.org/dc/elements/1.1/creator> <http://www.example.org/staffid/85740> . <http://www.example.org/staffid/85740> <http://example.org/terms/name> quot;J h S ithquot; . <htt // l /t / > quot;John Smithquot; <http://www.example.org/staffid/85740> <http://example.org/terms/age> quot;27quot; . 54 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  55. 55. The Semantic Web Stack RDF – Serialisation Turtle Example - Extended # Define some namespaces @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix dc: <http://purl.org/dc/elements/1.1/> . @prefix ex: <http://example org/terms/> . <http://example.org/terms/> <http://www.example.org/index.html> dc:creator <http://www.example.org/staffid/85740> . # write all statements in short form <http://www.example.org/staffid/85740> ex:name quot;John Smithquot;; ex:age quot;27quot; . 55 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  56. 56. The Semantic Web Stack RDF Extended Concepts Blank Nodes/ n-ary Relationships Example: „Pasta consists of 400g noodle & 100g sauce“ p „ g g consists of amount ex:Pasta ex:noodle „400g“ consists of amount ex:sauce „100g“ ex:Wok amount „400g“ consists of ex:Pasta ex:noodle consists of amount ex:sauce 56 „100g“ http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  57. 57. The Semantic Web Stack RDF Extended Concepts Blank Nodes/ n-ary Relationships Insertion of a „structure“ Node „ ex:noodle ingredient g amount „400g“ ex:MyNoodle y ingredient consists of ex:sauce ex:MySauce amount ex:Pasta consists of „100g“ 57 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  58. 58. The Semantic Web Stack RDF Extended Concepts Blank Nodes/ n-ary Relationships No URI‘s required for such nodes q ex:noodle ingredient g amount „400g“ ingredient consists of ex:sauce amount ex:Pasta „100g“ consists of Note: Semantics of Blank Nodes is not entirely clear (e.g. for 58 SPARQL)! http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  59. 59. The Semantic Web Stack RDF Extended Concepts Container Use Blank nodes to group different kinds of sets and lists Container: open Lists Can be extended by adding triples – rdf:Seq…ordered List – rdf:Bag…unordered List – rdf:Alt… alternative Selection (one of the items in the list) Collections: closed list Cannot be extended by adding triples (of course by changing triples) Note: Neither container nor blank nodes increase the expressiveness of RDF! 59 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  60. 60. The Semantic Web Stack RDF Extended Concepts Reification Making Statements over Statements „The detective assumes that the butler murdered Mr. X“ ex:murdered Ex:Mr. X ex:butler ex:assumes ex:Detective 60 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  61. 61. The Semantic Web Stack RDF Extended Concepts Reification „rdf:type Representation using „rdf:type“ property and Blank Nodes ex:butler rdf:subject rdf:Statement rdf:predicate Rdf:type ex:murdered d d rdf:object ex:vermutet ex:Mr. X Ex:Detective rdf:Statement defines the 61 Semantic On our way to RDFS and Ontologies http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  62. 62. The Semantic Web Stack Summary RDF An abstract model for representing metadata Standardisation for exchanging metadata Semantic is still missing Decentral manipulation of information p Different serialisation formats Graphs can be combined easily from different sources (if URI‘S are unique!) G h f l Graphs are a more powerful representation form than t ti f th tree‘s 62 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  63. 63. Points you should take away from this lecture What is the Semantic Web Stack? What are the restrictions of XML and XML-Schema in representing semantics? What is the basic idea and data model behind RDF? What is the difference between serialisation formats for RDF? What are Blank Nodes and Reification? 63 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  64. 64. Outlook Thursday, 16.10.08, Next Lecture on Thursday 16 10 08 10:15 The Semantic Web Stack (rep.) Semantics & Ontologies RDF Schema (RDFS) Web Ontology Language (OWL) (Logics in OWL) 64 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  65. 65. That‘s it for today… Thanks for your attention Questions/comments? mgranitzer@tugraz.at i @ 65 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
  66. 66. License This work is licensed under the Creative Commons Attribution 2.0 Austria License. To view a copy of this license, visit http://creativecommons org/licenses/by/2 0/at/ http://creativecommons.org/licenses/by/2.0/at/. Contributors: Mathias Lux Peter Scheir Klaus Tochtermann Michael Granitzer 66 http://kmi.tugraz.at WS 08/09 Wissenstechnologie @ kmi.tugraz.at
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