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A  Semantic  Multimedia Web: Create, Annotate, Present and Share your Media Raphaël Troncy,  < [email_address] > CWI, Inte...
Agenda <ul><li>Semantic Web technologies </li></ul><ul><ul><li>RDF: a general triple model for modeling information </li><...
RDF <ul><li>is the first layer of the Semantic Web standards </li></ul>
RDF <ul><li>stands for R esource  D escription  F ramework </li></ul>
RDF <ul><li>stands for R esource:   pages, images, videos , ...   everything that can have a URI D escription:   attribute...
R D F <ul><li>is a triple model  i.e.  every piece of knowledge is broken down into </li></ul><ul><li>  (  subject  ,  pre...
knowledge <ul><li>take for instance the following piece of </li></ul>
image.jpg has for creator Raphael and depicts the elephant Ganesh
image.jpg   has for creator  Raphael image.jpg   depicts  the elephant Ganesh
(  image.jpg  ,  creator  ,   Raphael  ) (  image.jpg  ,  depicts  ,   Elephant Ganesh  ) (  subject  ,  predicate  ,   ob...
R D F <ul><li>in  the atoms of knowledge are triples of the form ( subject , predicate , object ) </li></ul>
a triple the RDF atom Predicate Subject Object
<ul><li>is also a graph model to link the  descriptions  of resources </li></ul>RDF
<ul><li>triples can be seen as arcs of a graph ( vertex , edge , vertex ) </li></ul>RDF
Raphael creator    image.jpg  depicts Ganesh
<ul><li>in  resources and properties are identified by URIs  </li></ul>R D F http://mydomain.org/mypath/myresource
R D F <ul><li>in  values of properties can also be literals i.e. strings of characters </li></ul>
http://www.cwi.nl/~troncy#me http://purl.org/dc/elements/1.1#creator   http://flickr.com/photos/rtroncy/2923/   http://xml...
nodes RDF allows blank
anonymous a resource may be i.e.  not identified by a URI and noted _: xyz
e.g.,   there exists  an image about Ganesh
http://comm.semanticweb.org/core#Image rdf:type       _:x   http://xmlns.org/foaf/0.1/#depicts   &quot;Ganesh&quot;
break blank nodes the graph, they cannot be reused
name your resources and reuse existing names as much as possible
<ul><li><  /> has an XML syntax </li></ul>R D F
<ul><li>don't   run away </li></ul>
<ul><li><rdf:RDF xmlns:rdf=&quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#&quot; xmlns:dc=&quot;http://purl.org/dc/eleme...
<ul><li>it's only for ma chi nes </li></ul>
open-world assumption as opposed to the closed world assumption of classical systems
in short: the   absence   of a triple is  not  significant
(  image.jpg  ,  creator  ,  Raphael ) <ul><li>doesn't mean image.jpg has one creator </li></ul>
(  image.jpg  ,  creator  ,  Raphael ) <ul><li>means image.jpg has  at least  one creator </li></ul>
if you have no other triples giving authors it does not   mean they are not true .
RDF S <ul><li>stands for  R D F   Schema </li></ul>
RDF S <ul><li>provides primitives to write lightweight schemas for  R D F  triples </li></ul>
long way <ul><li>a little drop of semantics goes a </li></ul>
RDF S <ul><li>provides primitives to... </li></ul><ul><li>... define the vocabulary used in triples </li></ul><ul><li>... ...
RDF S <ul><li>to define classes of resources and organize their hierarchy </li></ul>
DOCUMENT REPORT
RDF S <ul><li>to define relations between resources and organize their hierarchy </li></ul>Tom Doc13 AUTHOR
CREATOR AUTHOR
RDF S <ul><li>allows for multiple inheritance for classes and properties </li></ul>
PERSON MAN MALE
RDFS <ul><li>relations have a  signature </li></ul>DOMAIN RANGE
RDFS <ul><li>relations have a  signature </li></ul><ul><li>... the  domain  is the type of the resource the relation start...
RDFS <ul><li>relations with several... </li></ul><ul><li>...  domains  mean all domains apply. </li></ul><ul><li>...  rang...
but looks like object programming,
properties <ul><li>are first class citizens, </li></ul><ul><li>they are not defined inside classes, </li></ul><ul><li>they...
no overwriting <ul><li>in particular a property can not be refined for sub classes of its range or domain. </li></ul>
multi-instantiation <ul><li>a resource can have several types, </li></ul><ul><li>it can be the instance of several classes...
RDF S <ul><li>provides primitives to... </li></ul><ul><li>... give labels ... </li></ul><ul><li>... give comments ... </li...
RDF... <ul><li>RDFS using the XML syntax for </li></ul>
<rdf:RDF xml:base=&quot;http://inria.fr/2005/humans.rdfs&quot;   xmlns:rdf =&quot;http://www.w3.org/1999/02/22-rdf-syntax-...
<rdf: Property  rdf:ID=&quot; hasMother &quot;>  < subPropertyOf  rdf:resource=&quot;# hasParent &quot;/>  < range  rdf:re...
RDF S <ul><li>semantics : standard inference rules to derive additional triples from known statements. </li></ul>
example of type propagation <ul><li>IF   (c 2 ,  subClassOf , c 1 ) AND   (x,  type , c 2 ) THEN   (x,  type , c 1 ) </li>...
example of property propagation <ul><li>IF   (p 2 ,  subPropertyOf , p 1 ) AND   (x, p 2  , y) THEN   (x, p 1  , y) </li><...
example of subClass transitivity <ul><li>IF   (c 2 ,  subClassOf , c 1 ) AND   (c 3 ,  subClassOf , c 2 )  THEN   (c 3 ,  ...
example of subProp transitivity <ul><li>IF   (p 2 ,  subPropertyOf , p 1 ) AND   (p 3 ,  subPropertyOf , p 2 )  THEN   (p ...
example of domain inference <ul><li>IF   (p 1 ,  domain , c 1 ) AND   (x, p 1 , y)  THEN   (x,  type , c 1 ) </li></ul>IF ...
example of range inference <ul><li>IF   (p 1 ,  range , c 1 ) AND   (x, p 1 , y)  THEN   (y,  type , c 1 ) </li></ul>IF   ...
<ul><li>OWL is a new layer on  top of RDFS </li></ul><ul><ul><li>OWL Lite </li></ul></ul><ul><ul><li>OWL DL </li></ul></ul...
 
 
 
Semantic Web Tutorials <ul><li>RDF in a nutshell </li></ul><ul><ul><li>Tutorial ( credits  @ Fabien  Gandon ) </li></ul></...
Agenda <ul><li>Semantic Web technologies </li></ul><ul><ul><li>RDF: a general triple model for modeling information </li><...
Modeling Vocabularies/Ontologies <ul><li>Approaches: </li></ul><ul><ul><li>Ontology learning </li></ul></ul><ul><ul><li>On...
Semantic principles <ul><li>Actor </li></ul><ul><ul><li>Role of a human being </li></ul></ul><ul><ul><li>Role in making mo...
Differential Principles Role Actor Director P3 : difference between the sibling nodes P4  :  common property shared by the...
Differential Principles <ul><li>Amount to  explicitly  specify what is understood when using a concept </li></ul><ul><li>F...
Extensional description of concepts Actor Linguistic semantics: Is a role: plays in a movie Denotation: {{w1: d11, d12..},...
Summary
DOE
OilEd
WebODE
OntoEdit
KAON Workbench
NeOn Toolkit
SWOOP
Protégé 4
How to support the  collaborative  ontology  modeling and editing task?
Knoodl
Collaborative  Protégé
 
Neologism SIOC example
Assignment <ul><li>VoCamp   like idea:  let's model some vocabularies ... </li></ul><ul><ul><li>Brainstorming: pick a doma...
Agenda <ul><li>Semantic Web technologies </li></ul><ul><ul><li>RDF: a general triple model for modeling information </li><...
Wake Up Video
Linked Data Principles <ul><li>Tim Berners Lee  [2006]   ( Design Issues ) </li></ul><ul><ul><li>Use URIs to identify thin...
Linked Data Issues <ul><li>Issues: </li></ul><ul><ul><li>These are principles, not implementation advices </li></ul></ul><...
The limit of content negotiation <ul><li>Is  conneg-ing  between  rdf+xml  and  video/*  a good behavior? </li></ul><ul><u...
The Web of Data <ul><li>Expose open datasets in RDF </li></ul><ul><li>Set RDF links among the data items for different dat...
DBpedia <ul><li>DBpedia is a community effort to: </li></ul><ul><ul><li>extract structured &quot;infobox&quot; information...
Scrapping infobox data http://dbpedia.org/resource/Madrid http://dbpedia.org/page/Madrid   http://dbpedia.org/data/Madrid....
Automatic Links Among Open Datasets Processors can switch automatically from one to the other …
Linked Data Cloud – March 2007
Linked Data Cloud – August 2007
Linked Data Cloud – March 2008
Linked Data Cloud – September 2008
Linked Data Cloud – March 2009
Searching Entities in the Cloud
Searching Linked Data
Linked Data goes mainstream
Cultural Heritage Data Cloud
Professional Art Annotation with Thesauri from the Web
Take Home Message <ul><li>Reuse what is there </li></ul><ul><ul><li>Of course, one could create RDF data manually … … but ...
Thanks for your attention http:// www.cwi.nl/~troncy
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A Semantic Multimedia Web (Part 2)

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A Semantic Multimedia Web: Part 2 of a series of lectures given at the Universidad Politécnica de Madrid (UPM), May 2009

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Transcript of "A Semantic Multimedia Web (Part 2)"

  1. 1. A Semantic Multimedia Web: Create, Annotate, Present and Share your Media Raphaël Troncy, < [email_address] > CWI, Interactive Information Access
  2. 2. Agenda <ul><li>Semantic Web technologies </li></ul><ul><ul><li>RDF: a general triple model for modeling information </li></ul></ul><ul><ul><li>RDFS / OWL: languages for representing ontologies on the web </li></ul></ul><ul><ul><li>SKOS: simple knowledge organization system </li></ul></ul><ul><li>Modeling your Ontology </li></ul><ul><ul><li>Methodologies for building ontologies </li></ul></ul><ul><ul><li>Tools for publishing vocabularies on the web </li></ul></ul><ul><li>Linked Data </li></ul><ul><ul><li>Expose you data following 4 basic principles </li></ul></ul><ul><ul><li>Re-use a growing amount of publicly open datasets </li></ul></ul><ul><ul><li>Applications powered by linked data </li></ul></ul>
  3. 3. RDF <ul><li>is the first layer of the Semantic Web standards </li></ul>
  4. 4. RDF <ul><li>stands for R esource D escription F ramework </li></ul>
  5. 5. RDF <ul><li>stands for R esource: pages, images, videos , ... everything that can have a URI D escription: attributes, features, and relations of the resources F ramework: model, languages and syntaxes for these descriptions </li></ul>
  6. 6. R D F <ul><li>is a triple model i.e. every piece of knowledge is broken down into </li></ul><ul><li> ( subject , predicate , object ) </li></ul>
  7. 7. knowledge <ul><li>take for instance the following piece of </li></ul>
  8. 8. image.jpg has for creator Raphael and depicts the elephant Ganesh
  9. 9. image.jpg has for creator Raphael image.jpg depicts the elephant Ganesh
  10. 10. ( image.jpg , creator , Raphael ) ( image.jpg , depicts , Elephant Ganesh ) ( subject , predicate , object )
  11. 11. R D F <ul><li>in the atoms of knowledge are triples of the form ( subject , predicate , object ) </li></ul>
  12. 12. a triple the RDF atom Predicate Subject Object
  13. 13. <ul><li>is also a graph model to link the descriptions of resources </li></ul>RDF
  14. 14. <ul><li>triples can be seen as arcs of a graph ( vertex , edge , vertex ) </li></ul>RDF
  15. 15. Raphael creator image.jpg depicts Ganesh
  16. 16. <ul><li>in resources and properties are identified by URIs </li></ul>R D F http://mydomain.org/mypath/myresource
  17. 17. R D F <ul><li>in values of properties can also be literals i.e. strings of characters </li></ul>
  18. 18. http://www.cwi.nl/~troncy#me http://purl.org/dc/elements/1.1#creator http://flickr.com/photos/rtroncy/2923/ http://xmlns.com/foaf/0.1#depicts Elephant Ganesh
  19. 19. nodes RDF allows blank
  20. 20. anonymous a resource may be i.e. not identified by a URI and noted _: xyz
  21. 21. e.g., there exists an image about Ganesh
  22. 22. http://comm.semanticweb.org/core#Image rdf:type _:x http://xmlns.org/foaf/0.1/#depicts &quot;Ganesh&quot;
  23. 23. break blank nodes the graph, they cannot be reused
  24. 24. name your resources and reuse existing names as much as possible
  25. 25. <ul><li>< /> has an XML syntax </li></ul>R D F
  26. 26. <ul><li>don't run away </li></ul>
  27. 27. <ul><li><rdf:RDF xmlns:rdf=&quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#&quot; xmlns:dc=&quot;http://purl.org/dc/elements/1.1/&quot; xmlns:foaf=&quot;http://xmlns.com/foaf/0.1/&quot; > <rdf:Description rdf:about= &quot;http://flickr.com/photos/rtroncy/2923&quot;> </li></ul><ul><li> <dc:creator rdf:resource= &quot; http://www.cwi.nl/~troncy#me &quot;/> <foaf:depicts> Ganesh </foaf:depicts> </rdf:Description> </li></ul><ul><li></rdf:RDF> </li></ul>
  28. 28. <ul><li>it's only for ma chi nes </li></ul>
  29. 29. open-world assumption as opposed to the closed world assumption of classical systems
  30. 30. in short: the absence of a triple is not significant
  31. 31. ( image.jpg , creator , Raphael ) <ul><li>doesn't mean image.jpg has one creator </li></ul>
  32. 32. ( image.jpg , creator , Raphael ) <ul><li>means image.jpg has at least one creator </li></ul>
  33. 33. if you have no other triples giving authors it does not mean they are not true .
  34. 34. RDF S <ul><li>stands for R D F Schema </li></ul>
  35. 35. RDF S <ul><li>provides primitives to write lightweight schemas for R D F triples </li></ul>
  36. 36. long way <ul><li>a little drop of semantics goes a </li></ul>
  37. 37. RDF S <ul><li>provides primitives to... </li></ul><ul><li>... define the vocabulary used in triples </li></ul><ul><li>... define elementary inferences </li></ul>
  38. 38. RDF S <ul><li>to define classes of resources and organize their hierarchy </li></ul>
  39. 39. DOCUMENT REPORT
  40. 40. RDF S <ul><li>to define relations between resources and organize their hierarchy </li></ul>Tom Doc13 AUTHOR
  41. 41. CREATOR AUTHOR
  42. 42. RDF S <ul><li>allows for multiple inheritance for classes and properties </li></ul>
  43. 43. PERSON MAN MALE
  44. 44. RDFS <ul><li>relations have a signature </li></ul>DOMAIN RANGE
  45. 45. RDFS <ul><li>relations have a signature </li></ul><ul><li>... the domain is the type of the resource the relation starts from. </li></ul><ul><li>... the range is the type of the resource the relation ends to. </li></ul>
  46. 46. RDFS <ul><li>relations with several... </li></ul><ul><li>... domains mean all domains apply. </li></ul><ul><li>... ranges mean all ranges apply. </li></ul><ul><li>Ranges and domains are optional </li></ul>
  47. 47. but looks like object programming,
  48. 48. properties <ul><li>are first class citizens, </li></ul><ul><li>they are not defined inside classes, </li></ul><ul><li>they have their own hierarchy. </li></ul>
  49. 49. no overwriting <ul><li>in particular a property can not be refined for sub classes of its range or domain. </li></ul>
  50. 50. multi-instantiation <ul><li>a resource can have several types, </li></ul><ul><li>it can be the instance of several classes </li></ul><ul><li>like multiple lights, facets on a resource. </li></ul>
  51. 51. RDF S <ul><li>provides primitives to... </li></ul><ul><li>... give labels ... </li></ul><ul><li>... give comments ... </li></ul><ul><li>... for classes and properties </li></ul>
  52. 52. RDF... <ul><li>RDFS using the XML syntax for </li></ul>
  53. 53. <rdf:RDF xml:base=&quot;http://inria.fr/2005/humans.rdfs&quot; xmlns:rdf =&quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#&quot; xmlns:rdfs=&quot;http://www.w3.org/2000/01/rdf-schema#&quot; xmlns=&quot;http://www.w3.org/2000/01/rdf-schema#> < Class rdf:ID=&quot; Man &quot;> < subClassOf rdf:resource=&quot;# Person &quot;/> < subClassOf rdf:resource=&quot;# Male &quot;/> <label xml:lang=&quot;en&quot;>man</label> <comment xml:lang=&quot;en&quot;>a male person</comment> </Class>
  54. 54. <rdf: Property rdf:ID=&quot; hasMother &quot;> < subPropertyOf rdf:resource=&quot;# hasParent &quot;/> < range rdf:resource=&quot;# Female &quot;/> < domain rdf:resource=&quot;# Human &quot;/> <label xml:lang=&quot;en&quot;>has for mother</label> <comment xml:lang=&quot;en&quot;>a female parent</comment> </rdf:Property> </rdf:RDF>
  55. 55. RDF S <ul><li>semantics : standard inference rules to derive additional triples from known statements. </li></ul>
  56. 56. example of type propagation <ul><li>IF (c 2 , subClassOf , c 1 ) AND (x, type , c 2 ) THEN (x, type , c 1 ) </li></ul>IF (Man, subClassOf , Person) AND (Tom, type , Man) THEN (Tom, type , Person)
  57. 57. example of property propagation <ul><li>IF (p 2 , subPropertyOf , p 1 ) AND (x, p 2 , y) THEN (x, p 1 , y) </li></ul>IF (author, subPropertyOf , creator) AND (Tom, author, Report12) THEN (Tom, creator, Report12)
  58. 58. example of subClass transitivity <ul><li>IF (c 2 , subClassOf , c 1 ) AND (c 3 , subClassOf , c 2 ) THEN (c 3 , subClassOf , c 1 ) </li></ul>IF (Person, subClassOf , Animal) AND (Man, subClassOf , Person) THEN (Man, subClassOf , Animal)
  59. 59. example of subProp transitivity <ul><li>IF (p 2 , subPropertyOf , p 1 ) AND (p 3 , subPropertyOf , p 2 ) THEN (p 3 , subPropertyOf , p 1 ) </li></ul>IF (parent, subPropertyOf , ancestor) AND (father, subPropertyOf , parent) THEN (father, subPropertyOf , ancestor)
  60. 60. example of domain inference <ul><li>IF (p 1 , domain , c 1 ) AND (x, p 1 , y) THEN (x, type , c 1 ) </li></ul>IF (author, domain , Human) AND (Tom, author, Report12) THEN (Tom, type , Human)
  61. 61. example of range inference <ul><li>IF (p 1 , range , c 1 ) AND (x, p 1 , y) THEN (y, type , c 1 ) </li></ul>IF (author, range , Document) AND (Tom, author, Report12) THEN (Report, type , Document)
  62. 62. <ul><li>OWL is a new layer on top of RDFS </li></ul><ul><ul><li>OWL Lite </li></ul></ul><ul><ul><li>OWL DL </li></ul></ul><ul><ul><li>OWL Full </li></ul></ul><ul><li>Actually, OWL is a restriction of RDF Classes  Properties  Individuals </li></ul>
  63. 66. Semantic Web Tutorials <ul><li>RDF in a nutshell </li></ul><ul><ul><li>Tutorial ( credits @ Fabien Gandon ) </li></ul></ul><ul><li>RDFS in a nutshell </li></ul><ul><ul><li>Tutorial ( credits @ Fabien Gandon ) </li></ul></ul><ul><li>Useful Resources </li></ul><ul><ul><li>http://www.w3.org/2001/sw/ </li></ul></ul><ul><ul><li>http://www.w3.org/People/Ivan/CorePresentations/ </li></ul></ul>
  64. 67. Agenda <ul><li>Semantic Web technologies </li></ul><ul><ul><li>RDF: a general triple model for modeling information </li></ul></ul><ul><ul><li>RDFS / OWL: languages for representing ontologies on the web </li></ul></ul><ul><ul><li>SKOS: simple knowledge organization system </li></ul></ul><ul><li>Modeling your Ontology </li></ul><ul><ul><li>Methodologies for building ontologies </li></ul></ul><ul><ul><li>Tools for publishing vocabularies on the web </li></ul></ul><ul><li>Linked Data </li></ul><ul><ul><li>Expose you data following 4 basic principles </li></ul></ul><ul><ul><li>Re-use a growing amount of publicly open datasets </li></ul></ul><ul><ul><li>Applications powered by linked data </li></ul></ul>
  65. 68. Modeling Vocabularies/Ontologies <ul><li>Approaches: </li></ul><ul><ul><li>Ontology learning </li></ul></ul><ul><ul><li>Ontology reuse </li></ul></ul><ul><ul><li>Competency questions </li></ul></ul><ul><li>Methodologies: </li></ul><ul><ul><li>Uschold and Grüninger </li></ul></ul><ul><ul><li>M ETHONTOLOGY : whole process of ontology engineering </li></ul></ul><ul><ul><li>Differential principles </li></ul></ul>
  66. 69. Semantic principles <ul><li>Actor </li></ul><ul><ul><li>Role of a human being </li></ul></ul><ul><ul><li>Role in making movies </li></ul></ul><ul><ul><li>Is a character in the movie </li></ul></ul><ul><li>Director </li></ul><ul><ul><li>Role of a human being </li></ul></ul><ul><ul><li>Role in making movies </li></ul></ul><ul><ul><li>Is not in the movie, but directs it </li></ul></ul>Generic “sèmes” Specific “sèmes”
  67. 70. Differential Principles Role Actor Director P3 : difference between the sibling nodes P4 : common property shared by the sibling nodes Plays in the movie Directs the movie P1: property with parent node (being a role of a human being) P2 : difference with parent node
  68. 71. Differential Principles <ul><li>Amount to explicitly specify what is understood when using a concept </li></ul><ul><li>Formulate the semantic commitment that should be respected to use concepts </li></ul>
  69. 72. Extensional description of concepts Actor Linguistic semantics: Is a role: plays in a movie Denotation: {{w1: d11, d12..}, {w2: d21, d22, …}…} Director: Linguistic semantics Is a role; Directs a movie Denotation: {{w1: d11, d12..}, {w2: d21, d22, …}…} Role of a human being <ul><li>Extensional red links: lattice structure is possible </li></ul><ul><li>Intensional black links : lattice structure is forbidden (tree) </li></ul>{Woody Allen, Clint Eastwood,…} forbidden
  70. 73. Summary
  71. 74. DOE
  72. 75. OilEd
  73. 76. WebODE
  74. 77. OntoEdit
  75. 78. KAON Workbench
  76. 79. NeOn Toolkit
  77. 80. SWOOP
  78. 81. Protégé 4
  79. 82. How to support the collaborative ontology modeling and editing task?
  80. 83. Knoodl
  81. 84. Collaborative Protégé
  82. 86. Neologism SIOC example
  83. 87. Assignment <ul><li>VoCamp like idea: let's model some vocabularies ... </li></ul><ul><ul><li>Brainstorming: pick a domain </li></ul></ul><ul><ul><li>Choose (essential) terms related to the domain </li></ul></ul><ul><ul><li>Sketch the model (blackboard) </li></ul></ul><ul><ul><li>Find and re-use existing vocabularies </li></ul></ul><ul><ul><li>Publish your model </li></ul></ul>
  84. 88. Agenda <ul><li>Semantic Web technologies </li></ul><ul><ul><li>RDF: a general triple model for modeling information </li></ul></ul><ul><ul><li>RDFS / OWL: languages for representing ontologies on the web </li></ul></ul><ul><ul><li>SKOS: simple knowledge organization system </li></ul></ul><ul><li>Modeling your Ontology </li></ul><ul><ul><li>Methodologies for building ontologies </li></ul></ul><ul><ul><li>Tools for publishing vocabularies on the web </li></ul></ul><ul><li>Linked Data </li></ul><ul><ul><li>Expose you data following 4 basic principles </li></ul></ul><ul><ul><li>Re-use a growing amount of publicly open datasets </li></ul></ul><ul><ul><li>Applications powered by linked data </li></ul></ul>
  85. 89. Wake Up Video
  86. 90. Linked Data Principles <ul><li>Tim Berners Lee [2006] ( Design Issues ) </li></ul><ul><ul><li>Use URIs to identify things (anything, not just documents); </li></ul></ul><ul><ul><li>Use HTTP URIs – globally unique names, distributed ownership – so that people can look up those names; </li></ul></ul><ul><ul><li>Provide useful information in RDF – when someone looks up a URI; </li></ul></ul><ul><ul><li>Include RDF links to other URIs – to enable discovery of related information </li></ul></ul>
  87. 91. Linked Data Issues <ul><li>Issues: </li></ul><ul><ul><li>These are principles, not implementation advices </li></ul></ul><ul><ul><li>Many things (deliberately?) kept blurry </li></ul></ul><ul><ul><li>Non-information resource vs information resource debate </li></ul></ul><ul><ul><ul><li>Architecture of the World Wide Semantic Web [ AWWSW ] </li></ul></ul></ul><ul><ul><ul><li>Ontology of Resources for Linked Data [ Halpin & Presutti ] </li></ul></ul></ul><ul><ul><li>Content Negotiation and 303, httpRange-14 resolution </li></ul></ul><ul><li>Formats: </li></ul><ul><ul><li>HTML + RDF/XML vs. RDFa </li></ul></ul>
  88. 92. The limit of content negotiation <ul><li>Is conneg-ing between rdf+xml and video/* a good behavior? </li></ul><ul><ul><li>Current configuration of jigsaw [ W3C Photo RDF ] </li></ul></ul><ul><ul><li>Equivalent: « Content is &quot;equivalent&quot; to other content when both fulfill essentially the same function or purpose upon presentation to the user » [ WAG ] </li></ul></ul><ul><ul><li>Abuse of content negotiation: what is the sameness of two representations of a resource? </li></ul></ul><ul><li>How to draw the line? </li></ul><ul><ul><li>Are an image and its ASCII version close enough to be content negotiated? </li></ul></ul><ul><ul><li>Is a transcoded media content still a fragment? </li></ul></ul>
  89. 93. The Web of Data <ul><li>Expose open datasets in RDF </li></ul><ul><li>Set RDF links among the data items for different datasets </li></ul><ul><li>Over 4.5 billion triples, 5 millions links (March 2009) </li></ul><ul><li>... still counting </li></ul>
  90. 94. DBpedia <ul><li>DBpedia is a community effort to: </li></ul><ul><ul><li>extract structured &quot;infobox&quot; information from Wikipedia </li></ul></ul><ul><ul><li>interlink DBpedia with other datasets on the Web </li></ul></ul>
  91. 95. Scrapping infobox data http://dbpedia.org/resource/Madrid http://dbpedia.org/page/Madrid http://dbpedia.org/data/Madrid.rdf
  92. 96. Automatic Links Among Open Datasets Processors can switch automatically from one to the other …
  93. 97. Linked Data Cloud – March 2007
  94. 98. Linked Data Cloud – August 2007
  95. 99. Linked Data Cloud – March 2008
  96. 100. Linked Data Cloud – September 2008
  97. 101. Linked Data Cloud – March 2009
  98. 102. Searching Entities in the Cloud
  99. 103. Searching Linked Data
  100. 104. Linked Data goes mainstream
  101. 105. Cultural Heritage Data Cloud
  102. 106. Professional Art Annotation with Thesauri from the Web
  103. 107. Take Home Message <ul><li>Reuse what is there </li></ul><ul><ul><li>Of course, one could create RDF data manually … … but that is unrealistic on a large scale </li></ul></ul><ul><ul><li>Goal is to generate RDF data automatically when possible and &quot;fill in&quot; by hand only when necessary </li></ul></ul><ul><ul><ul><li>service to get RDF from flickr images http://www.kanzaki.com/works/2005/imgdsc/flickr2rdf </li></ul></ul></ul><ul><ul><ul><li>service to get RDF from XMP http://www.ivan-herman.net/cgi-bin/blosxom.cgi/WorkRelated/SemanticWeb/xmpextract.html </li></ul></ul></ul><ul><li>Expose what you make </li></ul>
  104. 108. Thanks for your attention http:// www.cwi.nl/~troncy

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