Download - Wissenstechnologie Ii 08 09.Voll
Wissenstechnologie WS 08/09
Michael Granitzer
IWM TU Graz & Know-CenterIWM TU Graz & Know Center
http://kmi tugraz at http://www know center athttp://kmi.tugraz.at http://www.know-center.atThis 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/.
TodayToday
Topics of the practical excercise
Overview Semantic Web (Rep)
The Semantic Web StackU i d URI
2
• Unicode, URI• XML, XML Schema, Namespaces• Resource Description Framework
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Organization – Practical Excercise
Practical/technical or theoretical working out of particular topics in groups fof 2-4
Announced also on the bloghttp://kmi.tugraz.at/blogs/wissenstechnologie/ubungsthemen/
Passwort: wt08
Details: http://kmi.tugraz.at/blogs/wissenstechnologie/prufungsmodus/
Practical/technical Exerciseact ca /tec ca e c se
– Documentation (10%) – Implementation (45%) – Presentation 8.01. or 11.12. (45%)Presentation 8.01. or 11.12. (45%)
Theoretical Excercise
– Literature Gathering (Bibsonomy) (10%).
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– Written Summary (3500 words per group member) (45%) – Presentation 8.01. or 11.12. (45%)
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Organization – Scheduling
Milestone Theoretical Technical How?Milestone TheoreticalExercise
Technical Exercise
How?
Next Week Topic presentation In the lecture/ on (8.10.08) the blog
22.10.08 Topic selection and group announcement
via E-Mail to me
24.11.08 Gathering of relevant Literature finished
RequirementsDefinition finished
Bibsonomy/ Google Docs
11 12 08 & O l t ti O l t ti 11.12.08 & 08.01.09
Oral presentation of results & feedback from my side
Oral presentation of results & feedback from my side
429.01.09 Delivery of final
resultsDelivery of final results
Via Google Docs
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Excercise TopicsS h iftli h th ti h A b it
Topics of the practicalexcerciseSchriftlich theoretische Arbeiten
1. Überblick über Ontology Alignment und Ontology Matching Methoden
excercise
1. Überblick über Ontology Alignment und Ontology Matching Methoden
2. Eigenschaften, Indexstrukturen und erfolgreiche Anwendung von RDF Triple Stores
Ü3. Semantische Suchmaschinen im Überblick
4. Viral Marketing: Ausnutzung von Netzwerkeffekten im Marketing
5 Suchtechniken für Blogs und Folksonomies5. 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
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Überblick über existierende Open Source Lösungen
9. Ansätze zur Inhaltsextraktion auf Blog-Seiten
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Exercise TopicsS h iftli h th ti h A b it
Topics of the practicalexcerciseSchriftlich theoretische Arbeiten
Key Questions for the theoretical topics
excercise
Key Questions for the theoretical topics
What are the central question you want to address?
Wh t i th b d li t th t i ? What is the borderline to other topics?
What properties are important and how do they differentiate to other methods/tools/software?differentiate to other methods/tools/software?
What are the hard problems on the issue and what are the problems already solved?the problems already solved?
What are successful and unsuccessful practical examples?
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p
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Excercise TopicsP kti h t h i h A b it
Topics of the practicalexcercisePraktische technische Arbeiten
JavaDoc2RDF: Extraktion von Wissen aus Programm-
excercise
JavaDoc2RDF: Extraktion von Wissen aus ProgrammCode.
Semantik Web Service Kompositionp
Sesame SAIL Layers für HBASE
Experiment zur automatischen KontexterkennungExperiment zur automatischen Kontexterkennung
Erstellung von Ontologien basierend auf tags aus einer Web 2 0 Anwendung Web 2.0 Anwendung
Erstellung eines semantischen Media-Wikis und entsprechender Ontologie zur Unterstützung der
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p g gVorlesung Wissenstechnolgien
Ontology-based DBPedia browser
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(Größere Gruppe bevorzugt)
Excercise TopicsPraktische technische ArbeitenPraktische technische Arbeiten
Yahoo Answers: Corpus Mining Goal Extraction and Goal Yahoo Answers: Corpus Mining, Goal Extraction and Goal Graph Construction
Twitter: Corpus Mining and Goal Extraction, and Goal p g ,Graph Construction
Goal-Oriented Web Applications: Using a GOAL-REST API
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Exercise TopicsP ti l/t h i l i
Topics of the practicalexcercisePractical/technical exercise
Ask your advisor if you have any problems/questions
excercise
Ask your advisor if you have any problems/questions
Develop a requirements definition and software architecture.
Define the goal of your work?Define the goal of your work?
Sketch your solution/approach
Think of how to measure your resultsThink of how to measure your results
Narrow it down so that you think it is feasible
Implementation: Implementation:
If possible use Java
Keep it simple!
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Keep it simple!
Documentation using Google Docs and JavaDoc
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Exercise Topics Topics of the practicalexcerciseExercise Topics
Tutor: Thomas Stoppacher
excercise
Tutor: Thomas Stoppacher t.stoppacher at student.tugraz.at
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Questions
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The digital world (wide web) today OverviewSemantic Web (R )It’s size
Information growth per year
(Rep)
Information growth per year(including print, film, optical etc.)
Wachstum
999
800
900
1000
500
600
700
800
xaby
tes
160100
200
300
400Ex
It’s huge!12
1,6 50
100
1998 2000 2002 2004 2006 2008 2010 2012
Jahr
It s huge!It grows
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Intelligent Web = Semantic Web + Social WebWeb 3 0 = Semantic Web + Web 2 0 ;)Web 3.0 Semantic Web + Web 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)
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Search in the WWWAn example
OverviewSemantic Web (R )An example (Rep)
Image search for „Apache“
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The Problem of Relationships OverviewSemantic Web (R )
No Meaning of Realtionships
(Rep)
No Meaning of Realtionships
Who tried to shoot Mr. Burns in „Who shot Mr. Burns? Part 1“ (6. Season)( )
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Definition „Semantic Web“ OverviewSemantic Web (R )
The Semantic Web is an extension of the current Web in
(Rep)
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=00048144-10D2-1C70-84A9809EC588EF2110D2 1C70 84A9809EC588EF21
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The Vision as Application Scenario OverviewSemantic Web (R )
Plan a trip via the internet using your personal agent
(Rep)
Plan a trip via the internet using your personal agent
Agent searches automatically for
Suitable flightSuitable flight
Suitable hotels
Alternative routesAlternative routes
Also, the software agent tells you why it made this decision!
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Foundations of the Semantic Web OverviewSemantic Web (R )
Web of Data
(Rep)
Web of Data
Decentral Management of Information
Integration of heterogeneous informationIntegration of heterogeneous information
Standardized exchange of information between systems
Not only the bits but also the meaning!Not only the bits, but also the meaning!
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Foundations of the Semantic Web OverviewSemantic Web (R )From HTML… (Rep)
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Foundations of the Semantic Web OverviewSemantic Web (R )…to RDF (and further) (Rep)
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How to Express Semantics
The Semantic Web Stack
A small example
John Lennon
Th B tlBandIs Member Is A
The Beatles
Is MemberPaul McCartney
Query: all bands from EnglandIs born in
Founded in
Liverpool England
Query: all bands from England
?All bands with English artists?
Is born in
Ist in
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Liverpool England ?All bands with English artists?
Inferenz & Reasoning: E li h i P h i i d b i E l d
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English artists := Person who is an artist and born in England
Semantic Web Stack
The Semantic Web Stack
a.k.a. SW Layer Cakey
a.k.a. SW Tower
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Semantic Web Stack – the original one
The Semantic Web Stack
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Semantic Web Stack
The Semantic Web Stack
Unicode
URI
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Uniform Ressource Identifier (URI)
The Semantic Web Stack
Uniform Ressource Identifier (URI)
The Who ?=? Who
Decentrality requires unique identification of resources, conceptsetc.
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
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Uniform Ressource Identifier (URI)
The Semantic Web Stack
Examples
http://ftp.is.co.za/rfc/rfc1808.txt
mailto:[email protected]@ p
http://dbpedia.org/resource/Paul_McCartney
http://bio2rdf.org/protein:123790407
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http://bio2rdf.org/protein:123790407
http://www.w3.org/Addressing/
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http://www.w3.org/Addressing/
Unicode
The Semantic Web Stack
Universal Character Set
International Industry Standardy
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/
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p // g/ /
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Semantic Web Stack
The Semantic Web Stack
XML
XML Schema
Namespaces
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XML
The Semantic Web Stack
XML structured storage and serialisation of dataXML structured storage and serialisation of data
Representation of the logical structure of documents
Tree-based Representation:Tree-based Representation:
Tags (Opening & Closing) for structuring
Att ib tes fo specif ing p ope ties of TagsAttributes for specifying properties of Tags
Entities as abbrevations (e.g. ")
Language independent acess via SAX (Simple API forXML, event-based) and DOM (Document Object Model, tree based)
29Automatic determination of well formed XML
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XMLExample
The Semantic Web Stack
Example
<?xml version="1.0" encoding="UTF-8" ?><Person>
<name>Michael Granitzer </name><title>Dr.</title><lecture>
<name>Wissenstechnologien</name><name>Wissenstechnologien</name><number>702.111</number>
</lecture></Person>
? l i "1 0" di "UTF 8" ?<?xml version="1.0" encoding="UTF-8" ?><Person name=´Michael Granitzer´ title=´Dr.´>
<lecture name=´Wissenstechnologien´ number=´702.111´/></Person>
http://www.w3.org/DOM/
http://www.saxproject.org/
30Both are syntactically correct, which means well formed
But is the structure correct?
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XML Schema Languages
The Semantic Web Stack
Define the structure of an XML Document
DTD (Document Type Definition) DTD (Document Type Definition)
XML Schema
D fiDefine
What tag are following which tags
Optional and required attributes
Data type of an attribute/element
31XML Document is valid, if it meets the schema
http://www.w3.org/XML/Schema
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http://www.w3.org/XML/Schema
XML Schemasprachen - DTD
The Semantic Web Stack
<?xml version="1.0"?>
<note>
<to>Tove</to><to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body><body>Don't forget me this weekend!</body>
</note>
! ( f h di b d )<!ELEMENT note (to, from, heading, body)>
<!ELEMENT to (#PCDATA)>
<!ELEMENT from (#PCDATA)>
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<!ELEMENT heading (#PCDATA)>
<!ELEMENT body (#PCDATA)>
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http://www.w3schools.com/schema/schema_howto.asp
XML Schemasprachen - XML Schema
The Semantic Web Stack
XML Schemasprachen XML Schema
<?xml version="1.0"?>
<note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading>
<body>Don't forget me this weekend!</body> </note>
<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
l " "<xs:element name="note">
<xs:complexType> <xs:sequence>
<xs:element name="to" type="xs:string"/>
<xs:element name="from" type="xs:string"/> s:e e e t a e o type s:st g /
<xs:element name="heading" type="xs:string"/>
<xs:element name="body" type="xs:string"/>
</xs:sequence> </xs:complexType>
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</xs:element>
</xs:schema>
htt // 3 h l / h / h h t
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http://www.w3schools.com/schema/schema_howto.asp
Namespaces
The Semantic Web Stack
Equal tag names in a different context<note> <animal>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<gender>M</gender>
<body><legs>4</legs>
<body>Don't forget
me this weekend!</body>
</note>
…</body>
</animal>/
Namespaces can be specified per element<Element-Name xmlns[:prefix]=uri>
34Valid within the element
http://www.w3.org/TR/REC-xml-names/
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NamespacesExample
The Semantic Web Stack
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>
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Drawbacks of XML
The Semantic Web Stack
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Drawbacks of XML
The Semantic Web Stack
No semantic/meaning of tags No semantic/meaning of tags
Tree-like structure makes it hard to combine decentralstored information
<Person>
<name> x</name>
<lecture>
/<name> x</name>
<lecture>
…</lecture>
<name> x</name>
<Person>
…/
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</lecture>
</Person>
</Person>
</lecture>
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Semantic Web Stack
The Semantic Web Stack
RDF
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RDF - Resource Description Framework
The Semantic Web Stack
RDF Resource Description Framework
RDF is like my eccentric old uncle I don't know him as well RDF is like my eccentric old uncle. I don t know him as well as I'd like, which is partly his fault, since his eccentricitiescan be off-putting. Of course they're what make him so interesting and are the reason I want to get to know himinteresting and are the reason I want to get to know himbetter in the first place.
[Kendall Grant Clark 2002][Kendall Grant Clark 2002]http://www.xml.com/pub/a/2002/11/13/deviant.html
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Goal of RDF
The Semantic Web Stack
Description of (Web) resource via metadataDescription of (Web) resource via metadata
Historically focused on web sites
E t d d t l“ Extended to „general“ resources
For
Classification of resources
Classification of relationships between resources
Unambigious description
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Unambigious description
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Application Examples Today
The Semantic Web Stack
RSS 1 0: RDF Site Summary (not RSS 2 0)RSS 1.0: RDF Site Summary (not RSS 2.0)
Dublin Core Metadata Standard
Ad b XMP f b ddi bj tAdobe XMP for embedding objects
Simple Knowledge Organisation Scheme (SKOS)
DBPedia
….
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Classical Metadata
The Semantic Web Stack
Classical Metadata are mostly key/value pairs: Classical Metadata are mostly key/value pairs:
Resource: http://www.know-center.at/xyz.ppt
Type: PowerPoint Presentationyp
Author: Michael Granitzer
Topic: RDF
In XML (Example):
<presentation src='http://www.know-center.at/xyz.ppt'><author> Michael Granitzer</author><topic>RDF</topic>
42</presentation>
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RDF Basics
The Semantic Web Stack
Resources RResources 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
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Identified via URI s
Combined into statements
http://www.w3.org/TR/rdf-concepts/
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p // g/ / p /
RDF Statement (Triples)
The Semantic Web Stack
Statement := <Subject Predicate Object>Statement := <Subject, Predicate, Object>
[Michael Granitzer, is author of, Presentation XYZ]
Michael Granitzer … Subject
is author of … Predicate
Presentation XYZ … Object
Michael PresentatiIs author of
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Granitzer on XYZ
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RDF Statements (Triples)
The Semantic Web Stack
A small example
htt // iki di / iki/J h L http://dbpedia org/property/associatedActshttp://en.wikipedia.org/wiki/John_Lennon
http://en.wikipedia.org/wiki/The_Beatles
http://dbpedia.org/property/associatedActs
http://en.wikipedia.org/wiki/Paul_McCartney
rdfs:label
http://dbpedia.org/property/associatedActs
Subject Predicate Object
„Paul McCartney“
j j
http://en.wikipedia.org/wiki/John_Lennon
http://dbpedia.org/property/associatedActs
http://en.wikipedia.org/wiki/The_Beatles
45http://en.wikipedia.org/wiki/Paul_McCartney
http://dbpedia.org/property/associatedActs
http://en.wikipedia.org/wiki/The_Beatles
http://en.wikipedia.org/wiki/P Rdfs:label “Paul McCartney”
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aul_McCartney
RDF URIHow to make a URI unique?
The Semantic Web Stack
How to make a URI unique?
No technical enforcement, just recommendations from W3C, j
Specialised Vocabulary
Phone Numbers (e.g. tel://+43-316-873-9263)http://www.rfc-editor.org/rfc/rfc3966.txthttp://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 may not existURI s may not exist
Be carefull with the semantic:
– „Shakespear“ is author of „http://de.wikipedia.org/wiki/Othello“
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„ p „ p p g– „Shakespear“ is author of „http://de.wikipedia.org/wiki/Othello#URI“
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RDF – SerialisationRDF/XML
The Semantic Web Stack
RDF/XML
RDF/XML serialises RDF Modells using XML/ g
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“ attributReference to the resource via about „URI attribut
Properties of a resource as enclosing tag after rdf:Description
http://www.w3.org/TR/rdf-syntax-grammar/
http://www.w3.org/RDF/Validator/
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RDF – SerialisationRDF/XML Example
The Semantic Web Stack
RDF/XML Example
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:dc="http://purl org/dc/elements/1 1/"xmlns:dc http://purl.org/dc/elements/1.1/
xmlns:ex="http://example.org/terms/">
<rdf:Description rdf:about="http://www.example.org/index.html">
<dc:creator rdf:resource="http://www example org/staffid/85740" /><dc:creator rdf:resource="http://www.example.org/staffid/85740" />
</rdf:Description>
<rdf:Description rdf:about="http://www.example.org/staffid/85740"
" h S i h" /ex:name="John Smith" />
<rdf:Description rdf:about="http://www.example.org/staffid/85740"
ex:age="27" />
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</rdf:RDF>
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RDF – SerialisationRDF/XML-ABBREV
The Semantic Web Stack
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<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 FrameworkFramework
http://www.w3.org/TR/rdf-syntax-grammar/
http://www.w3.org/TR/2004/REC-rdf-primer-20040210/
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RDF – SerialisationRDF/XML-ABBREV Example
The Semantic Web Stack
RDF/XML-ABBREV Example
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:dc="http://purl org/dc/elements/1 1/"xmlns:dc http://purl.org/dc/elements/1.1/
xmlns:ex="http://example.org/terms/">
<rdf:Description rdf:about="http://www.example.org/index.html">
<dc:creator><dc:creator>
<rdf:Description rdf:about="http://www.example.org/staffid/85740"
ex:name="John Smith"
"27" /ex:age="27" />
</dc:creator>
</rdf:Description>
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</rdf:RDF>
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RDF – SerialisationRDF/XML Pros & Cons
The Semantic Web Stack
RDF/XML Pros & Cons
++: Use Standardized serialisation format
~~: RDF requires namespaces: no „:“ in attribute names
<rdf:Description rdf:about="http://www.example.org/index.html">
<rdf:Description http://www.w3.org/1999/02/22-rdf-syntax-ns#about="http://www.example.org/index.html">
--: No „-“ after a „:“ in tag names
<alter:-100>
--: Namespaces not usable in attributes<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
l htt // l /“xmlns:ex = „http://www.example.org/“>
<rdf:Description rdf:about=„ex:index.html">
Different notations for equal URI‘s
51
Different notations for equal URI‘s
Very complex and hard to read for humans
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RDF – SerialisationN3 – Notation 3 N-Triples Turtle
The Semantic Web Stack
N3 – Notation 3, N-Triples, Turtle
Notation 3 1998 introduced by Tim Berners-LeeNotation 3 1998 introduced by Tim Berners Lee
Write RDF Graph as set of triples
– For each subject write all predicate object pairs separated by „;“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
52http://www.w3.org/2001/sw/RDFCore/ntriples/
http://www.dajobe.org/2004/01/turtle/
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RDF – SerialisationN3 – Notation 3 N-Triples Turtle
The Semantic Web Stack
N3 – Notation 3, N-Triples, Turtle
53See
http://www.w3.org/DesignIssues/Notation3.html
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RDF – SerialisationN-Triples/Turtle Example
The Semantic Web Stack
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> <htt // l /t / > "J h S ith"<http://example.org/terms/name> "John Smith" .
<http://www.example.org/staffid/85740> <http://example.org/terms/age> "27" .
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RDF – SerialisationTurtle Example - Extended
The Semantic Web Stack
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/>@prefix ex: <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 "John Smith";
ex:age "27" .
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RDF Extended ConceptsBlank Nodes/ n-ary Relationships
The Semantic Web Stack
Blank Nodes/ n-ary Relationships
Example: „Pasta consists of 400g noodle & 100g sauce“p „ g g
ex:Pasta ex:noodleconsists of
„400g“
amount
ex:sauce
consists of
„100g“amount
ex:Wok
„400g“amount
ex:Pasta ex:noodleconsists of
56ex:sauce
consists of
amount
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„100g“
RDF Extended ConceptsBlank Nodes/ n-ary Relationships
The Semantic Web Stack
Blank Nodes/ n-ary Relationships
Insertion of a „structure“ Node„
ex:noodleingredient
„400g“amount
ex:MyNoodle
g
ex:sauce
y
ingredientconsists of
ex:Pastaamountex:MySauce
consists of
57„100g“
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RDF Extended ConceptsBlank Nodes/ n-ary Relationships
The Semantic Web Stack
Blank Nodes/ n-ary Relationships
No URI‘s required for such nodesq
ex:noodleingredient
„400g“amount
g
ex:sauceingredient
consists of
ex:Pasta „100g“amount
consists of
58Note: Semantics of Blank Nodes is not entirely clear (e.g. forSPARQL)!
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SPARQL)!
RDF Extended ConceptsContainer
The Semantic Web Stack
Container
Use Blank nodes to group different kinds of sets and listsUse Blank nodes to group different kinds of sets and lists
Container: open ListsCan be extended by adding triples
– rdf:Seq…ordered List– rdf:Bag…unordered List– rdf:Alt… alternative Selection (one of the items in the list)rdf:Alt… alternative Selection (one of the items in the list)
Collections: closed listCannot be extended by adding triples (of course byCannot be extended by adding triples (of course bychanging triples)
59Note: Neither container nor blank nodes increase theexpressiveness of RDF!
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RDF Extended ConceptsReification
The Semantic Web Stack
Reification
Making Statements over StatementsMaking Statements over Statements
„The detective assumes that the butler murdered Mr. X“
ex:butlerEx:Mr. Xex:murdered
ex:assumes
60
ex:Detective
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RDF Extended ConceptsReification
The Semantic Web Stack
Reification
Representation using „rdf:type“ property and Blank NodesRepresentation using „rdf:type property and Blank Nodes
ex:butler rdf:subjectrdf:Statement
d drdf:predicate Rdf:type
ex:murdered
ex:vermutetrdf:object
61rdf:Statement defines theSemantic On our way to RDFS and Ontologies
Ex:Detectiveex:Mr. X
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Semantic On our way to RDFS and Ontologies
Summary RDF
The Semantic Web Stack
An abstract model for representing metadataAn abstract model for representing metadata
Standardisation for exchanging metadata
Semantic is still missingSemantic is still missing
Decentral manipulation of informationp
Different serialisation formats
Graphs can be combined easily from different sources (ifURI‘S are unique!)
G h f l t ti f th
62
Graphs are a more powerful representation form than tree‘s
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Points you should take away from thislecturelecture
What is the Semantic Web Stack?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 behindRDF?
What is the difference between serialisationformats for RDF?
What are Blank Nodes and Reification?What are Blank Nodes and Reification?
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Outlook
Next Lecture on Thursday 16 10 08 10:15Next Lecture on Thursday, 16.10.08, 10:15
The Semantic Web Stack (rep.)The Semantic Web Stack (rep.)
Semantics & Ontologies
RDF Schema (RDFS)
Web Ontology Language (OWL)
64(Logics in OWL)
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That‘s it for today…
Thanks for your attention
Questions/comments?
65
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License
This work is licensed under the Creative Commons 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
66Michael Granitzer
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