Semantic Web fundamentals
    - information linking and layering in practice

    (or: what RDF might do for Drupal)




 ...
OVERVIEW
- Where I’m coming from
- Layered & linked information
 - Web History & Linking Open Data
- What’s out there now:...
RDFa?


• “I don’t know what it is, but Dries likes it”
• a set of attributes for adding typed links
  and properties to d...
Semantic Web & RDF
 (De-fragmenting the Web of data?)
danbri@danbri.org
• Accidental standards-nerd
• Making things in the Web since ’94
• Found metadata community & W3C
  thro...
LAYERED
INFORMATION
Calendar Layers
Pixel Layers
Map Layers
http://data-gov.tw.rpi.edu/demo/exhibit/earthquake.html
Layers of data?
Can we also “layer” the kind of information
we find in ordinary Web pages & databases?
How do we select, co...
What links the layers?


• when we don’t have time & space indexes...
LINKED
     INFORMATION
• Good old-fashioned HTML hyperlinks
• Data files that form a Web (Linked Data)
• Two documents men...
WEB HISTORY
Where the Web came from...




Original image credits: Tim Berners-Lee
Aside: RDF Data Model
Image credits: Tim Berners-Lee, Ian Davis
Links!
Layers?
Hmm......
alice.example.com



bob.example.org




school.example.net
http://www.w3.org/DesignIssues/LinkedData.html

     “The Semantic Web isn't just about putting data on
    the web. It is...
Aside: the value of linking
Examples

• GMail - labelling messages or conversations
• W3C POWDER - label pages or collections?
• Google Social Graph A...
WHAT’S OUT THERE?
RDF DATA - lots
    From lifescience data and all the BBC’s TV and music
    listings to FOAF profiles, agricultural resear...
UN-FAO Geo-political Ontology


                          hasBorderWith, hasMember, isAdministeredBy,
                    ...
... a SKOS/RDF concept scheme
Library of Congress
Subject Headings (LCSH)
 “The Library of Congress Authorities and Vocabularies service enables both hu...
LCSH topics for Paris
More linked data on Paris...

In HTML at http://www.geonames.org/2988507/paris.html
        <link rel="alternate" type="ap...
In http://dbpedia.org/resource/Paris

    populationTotal 2167994, cityMotto ..., coatOfArmsLegend ..., skos:subject
    W...
BBC Music - Linked Data
Data: In Summary...
                 More every day.

          Increasingly cross-referenced.

    All use RDF’s data mod...
FOAF visualization by Tim O’Brien
http://www.flickr.com/photos/timobrien/sets/794898/
Data ecosystem?
SEARCH
Yahoo’s BOSS (Build your Own Search Service):
  “By combining your unique assets and ideas with
  our search technology as...
Google Rich Snippets: RDFa & Microformats
FILES & WORKFLOW
Adobe XMP:
  Since 2001, RDF/XML inside TIFF, JPEG, PNG, GIF, PDF, ...




OpenOffice.org & OASIS OpenDocu...
DRUPAL
RDF in Drupal
DC - Dublin Core Metadata Initiative
DC & Education
DC & Museums
DC & Libraries...
SKOS
& the “cold start” taxonomy problem
SKOS in Drupal
“OrganiK extends the Taxonomy XML module by adding SKOS support.                                           Load...
  This ...
Edit...
Update...
Publish...
Drupal Fields API

• Attach arbitrary properties to anything in
  Drupal 7
• RDF does the same for the Web at large
• Natu...
Drupal & Taxonomies
• Many existing add-ons, patches, applications
• SKOS (a W3C standard since August :) will
  bring doz...
Drupal & Data APIs
• SPARQL is to RDF as SQL is to RDBMs
• SPARQL scripting looks very familiar to
  anyone working with S...
Drupal RDFa
• the “lowest hanging fruit”
• data need no longer be hidden in the db
• SEO (Yahoo searchmonkey, Google
  Sni...
Acronym Recap

• RDF is a data model for linked/layered data
• “Links” are made with URIs
• “Layers” represent independent...
Creating RDF

• Types of thing (classes) and relationship
  (property) are defined using RDFS and OWL
• So there is an RDFS...
Sharing RDF

• RDF/XML is the oldest RDF syntax
• RDFa is new, integrates with XHTML
• GRDDL lets you map from other XML o...
Querying RDF:
         SPARQL
• a language for asking questions
• looks a lot like SQL, but simpler and webby
• comes with...
POWDER
• let’s you say “everything on
  mp3.myserver.example.com/ is a CC-SA-
  licensed MP3 music file”
• Or that “everyth...
SKOS

• Simple Knowledge Organization Systems
• An RDF-based way of encoding thesauri
• Or other things that are thesaurus...
Summary
There’s a growing ecosystem around linked RDF data.

   Drupal can expect to manage files containing it,
   link to...
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
SemWeb Fundamentals - Info Linking & Layering in Practice
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SemWeb Fundamentals - Info Linking & Layering in Practice

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... in which I try to frame RDF in terms of data that can be linked and layered. Not entirely successful, but here are the slides anyway.

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  • I&amp;#x2019;m going to try to do 3 things in 5 minutes:
    - a brief introduction to the Friend of the Friend project;
    - a tribute to the graphic design skills of TimBL,
    - and tell a story about what we&amp;#x2019;re really doing in the wider Semantic Web project, about why the Web is only just getting started.



  • You&amp;#x2019;ll all have seen Tim&amp;#x2019;s &amp;#x201C;vague but exciting&amp;#x201D; 1989 memo. Here it is again.



    The memo opens with an evocating image showing a Web of &amp;#x201C;nodes&amp;#x201D;, but there&amp;#x2019;s a hidden mystery.



    But are these documents that are interlinked, or things in the real world described by documents, or ... somehow both? It shows people and groups (Tim, CERN), ... but hey, how do they get into the Web?



    The Semantic Web project is an effort to unravel this mystery and pursue the original vision of a Web that better reflects our complex reality. FOAF began as an experiment to explore these issues.







  • You&amp;#x2019;ll all have seen Tim&amp;#x2019;s &amp;#x201C;vague but exciting&amp;#x201D; 1989 memo. Here it is again.



    The memo opens with an evocating image showing a Web of &amp;#x201C;nodes&amp;#x201D;, but there&amp;#x2019;s a hidden mystery.



    But are these documents that are interlinked, or things in the real world described by documents, or ... somehow both? It shows people and groups (Tim, CERN), ... but hey, how do they get into the Web?



    The Semantic Web project is an effort to unravel this mystery and pursue the original vision of a Web that better reflects our complex reality. FOAF began as an experiment to explore these issues.







































































  • The World Wide Web is the most successful linked information system that has ever existed. Hidden away in the original 1989 CERN memo proposing the Web are several ideas that are only now reaching fruition via W3C&apos;s RDF technology stack. This talk will show in practice how the full 1989 vision for the Web is being realised using RDF-based technologies (RDF/RDFa, SKOS, SPARQL, FOAF, OWL), and how the two concepts of information
    linking
    , and information
    layering
    are all you really need to understand a powerful suite of tools and standards for Web-based data sharing. You&apos;ll learn how the work of librarians, open source advocates, computer scientists and open data activists find common ground in the Semantic Web project, and how the growing Web of linked open data can fit into everyday technology projects.

















































  • SemWeb Fundamentals - Info Linking & Layering in Practice

    1. 1. Semantic Web fundamentals - information linking and layering in practice (or: what RDF might do for Drupal) Dan Brickley, danbri@danbri.org (Vrije Universiteit Amsterdam)
    2. 2. OVERVIEW - Where I’m coming from - Layered & linked information - Web History & Linking Open Data - What’s out there now: data, apps, ecosystem - Semantic Web standards - acronym attack: - RDF/S, OWL, SPARQL, SKOS, RDFa - POWDER, GRDDL, RDB2RDF... - What’s in it for Drupal & its users?
    3. 3. RDFa? • “I don’t know what it is, but Dries likes it” • a set of attributes for adding typed links and properties to document markup • a bit like microformats, but with different strengths & weaknesses • a way of putting data into Web pages
    4. 4. Semantic Web & RDF (De-fragmenting the Web of data?)
    5. 5. danbri@danbri.org • Accidental standards-nerd • Making things in the Web since ’94 • Found metadata community & W3C through trying to make better Web sites • W3C staff ‘99-’05, edited RDFS, co-chaired RDFCore work; SKOS, POWDER; FOAF... • TV stuff at Joost & now VU University Amsterdam, see www.NoTube.tv
    6. 6. LAYERED INFORMATION
    7. 7. Calendar Layers
    8. 8. Pixel Layers
    9. 9. Map Layers
    10. 10. http://data-gov.tw.rpi.edu/demo/exhibit/earthquake.html
    11. 11. Layers of data? Can we also “layer” the kind of information we find in ordinary Web pages & databases? How do we select, compose, compare layers? How do we figure out when two data sources are talking about the same thing? How can we model, create, publish, consume, and query general-purpose layered data?
    12. 12. What links the layers? • when we don’t have time & space indexes...
    13. 13. LINKED INFORMATION • Good old-fashioned HTML hyperlinks • Data files that form a Web (Linked Data) • Two documents mentioning same thing • Two identifiers referring to the same thing • Typed links between things (including docs)
    14. 14. WEB HISTORY
    15. 15. Where the Web came from... Original image credits: Tim Berners-Lee
    16. 16. Aside: RDF Data Model
    17. 17. Image credits: Tim Berners-Lee, Ian Davis
    18. 18. Links! Layers?
    19. 19. Hmm......
    20. 20. alice.example.com bob.example.org school.example.net
    21. 21. http://www.w3.org/DesignIssues/LinkedData.html “The Semantic Web isn't just about putting data on the web. It is about making links, so that a person or machine can explore the web of data.   With linked data, when you have some of it, you can find other, related, data.” “1. Use URIs as names for things. 2. Use HTTP URIs so that people can look up those names. 3. When someone looks up a URI, provide useful information, using the standards. 4. Include links to other URIs. so that they can discover more things.” From linked documents to databases & websites...
    22. 22. Aside: the value of linking
    23. 23. Examples • GMail - labelling messages or conversations • W3C POWDER - label pages or collections? • Google Social Graph API - data linking • Biz/ed Web site - my first webmaster job
    24. 24. WHAT’S OUT THERE?
    25. 25. RDF DATA - lots From lifescience data and all the BBC’s TV and music listings to FOAF profiles, agricultural research, views of bestbuy.com for machines, and an ever growing collection of taxonomies and thesauri. Thesauri and taxonomies? - formal, logical taxonomies - OWL, Web Ontology Language - library-style thesauri, looser topical concept hierarchies - SKOS
    26. 26. UN-FAO Geo-political Ontology hasBorderWith, hasMember, isAdministeredBy, isInGroup, isPredecessorOf, isSuccessorOf... An RDFS/OWL taxonomy...
    27. 27. ... a SKOS/RDF concept scheme
    28. 28. Library of Congress Subject Headings (LCSH) “The Library of Congress Authorities and Vocabularies service enables both humans and machines to programmatically access authority data at the Library of Congress. This service is influenced by -- and implements -- the Linked Data movement's approach of exposing and inter-connecting data on the Web via dereferenceable URIs.” One XHTML/RDFa page per topic, eg. http://id.loc.gov/authorities/sh95000541 http://id.loc.gov/authorities/
    29. 29. LCSH topics for Paris
    30. 30. More linked data on Paris... In HTML at http://www.geonames.org/2988507/paris.html <link rel="alternate" type="application/rdf+xml" title="RDF Version" href="http://sws.geonames.org/2988507/about.rdf" /> In RDF/XML at http://sws.geonames.org/2988507/about.rdf <rdf:RDF> <Feature rdf:about="http://sws.geonames.org/2988507/"> <name>Paris</name> <alternateName xml:lang="ja"> </alternateName> <featureClass rdf:resource="http://www.geonames.org/ontology#P"/> <featureCode rdf:resource="http://www.geonames.org/ontology#P.PPLC"/> <inCountry rdf:resource="http://www.geonames.org/countries/#FR"/> <population>2138551</population> <postalCode>75000</postalCode> <wgs84_pos:lat>48.85341</wgs84_pos:lat> <wgs84_pos:long>2.3488</wgs84_pos:long <wikipediaArticle rdf:resource="http://en.wikipedia.org/wiki/Paris"/> <owl:sameAs rdf:resource="http://dbpedia.org/resource/Paris"/>
    31. 31. In http://dbpedia.org/resource/Paris populationTotal 2167994, cityMotto ..., coatOfArmsLegend ..., skos:subject World_Heritage_Sites_in_France, ... birthplace Alexis_de_Tocqueville, Jean_Genet, Guy_Debord, ..., .... owl:sameAs http://sws.geonames.org/2988507/ owl:sameAs http://www.freebase.com/view/en/paris In http://rdf.freebase.com/rdf/en.paris <fb:olympics.olympic_city_bid rdf:about="http://rdf.freebase.com/ns/guid.9202a8c04000641f8000000008caf949"> <fb:olympics.olympic_city_bid.olympic_games rdf:resource="http://rdf.freebase.com/ns/en.2008_summer_olympics"/> <fb:olympics.olympic_city_bid.bidding_city rdf:resource="http://rdf.freebase.com/ns/en.beijing"/> <fb:olympics.olympic_city_bid.bidding_city> <fb:location.administrative_division rdf:about="http://rdf.freebase.com/ns/en.paris"> <fb:travel.travel_destination.tourist_attractions rdf:resource="http://rdf.freebase.com/ns/en.ile_de_la_cite"/> <fb:travel.travel_destination.tourist_attractions rdf:resource="http://rdf.freebase.com/ns/en.eiffel_tower"/> <fb:travel.travel_destination.tourist_attractions rdf:resource="http://rdf.freebase.com/ns/en.champs-elysees"/> <fb:travel.travel_destination.tourist_attractions rdf:resource="http://rdf.freebase.com/ns/en.notre_dame_de_paris"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.ronin_1998"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.breathless"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.amelie"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.charade"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.paris_when_it_sizzles"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.les_amants_du_pont_neuf"/> <fb:film.film_location.featured_in_films rdf:resource="http://rdf.freebase.com/ns/en.the_dinner_game"/>
    32. 32. BBC Music - Linked Data
    33. 33. Data: In Summary... More every day. Increasingly cross-referenced. All use RDF’s data model and vocabularies. Some write RDF in RDF/XML, others XHTML/RDFa. Varying focus, detail, quality, linkage. Serious Library RDF data in Dublin Core and SKOS.
    34. 34. FOAF visualization by Tim O’Brien http://www.flickr.com/photos/timobrien/sets/794898/
    35. 35. Data ecosystem?
    36. 36. SEARCH
    37. 37. Yahoo’s BOSS (Build your Own Search Service): “By combining your unique assets and ideas with our search technology assets, BOSS is a platform for the next generation of search innovation, serving hundreds of millions of users across the Web.”
    38. 38. Google Rich Snippets: RDFa & Microformats
    39. 39. FILES & WORKFLOW Adobe XMP: Since 2001, RDF/XML inside TIFF, JPEG, PNG, GIF, PDF, ... OpenOffice.org & OASIS OpenDocument Format 1.2: Multi-file archives, with a manifest.rdf and inline RDFa (coming soon...) OpenOffice.org report 2.5 Million download / week, > 100 million users.
    40. 40. DRUPAL
    41. 41. RDF in Drupal
    42. 42. DC - Dublin Core Metadata Initiative
    43. 43. DC & Education
    44. 44. DC & Museums
    45. 45. DC & Libraries...
    46. 46. SKOS & the “cold start” taxonomy problem
    47. 47. SKOS in Drupal
    48. 48. “OrganiK extends the Taxonomy XML module by adding SKOS support. Load... This allows you to import/export taxonomies using SKOS.” "OrganiK is a partially EU-funded Research project for the benefit of SMEs." http://www.organik-project.eu/ see also: http://drupal.org/node/560326
    49. 49. Edit...
    50. 50. Update...
    51. 51. Publish...
    52. 52. Drupal Fields API • Attach arbitrary properties to anything in Drupal 7 • RDF does the same for the Web at large • Natural to bridge these two
    53. 53. Drupal & Taxonomies • Many existing add-ons, patches, applications • SKOS (a W3C standard since August :) will bring dozens of thesauri, glossaries etc. • News sites can be pre-populated with externally managed categories and topics • Using standard identifiers for topics aids aggregators
    54. 54. Drupal & Data APIs • SPARQL is to RDF as SQL is to RDBMs • SPARQL scripting looks very familiar to anyone working with SQL • Drupal code can call external SPARQL DBs • SPARQL queries can include “GRAPH” clauses which specify chosen data layers...
    55. 55. Drupal RDFa • the “lowest hanging fruit” • data need no longer be hidden in the db • SEO (Yahoo searchmonkey, Google Snippets), cross-linking and improved search • A foundation to build on
    56. 56. Acronym Recap • RDF is a data model for linked/layered data • “Links” are made with URIs • “Layers” represent independent data sources
    57. 57. Creating RDF • Types of thing (classes) and relationship (property) are defined using RDFS and OWL • So there is an RDFS or OWL definition for all the terms defined by Dublin Core, FOAF etc. • Basically a simple machine-readable dictionary
    58. 58. Sharing RDF • RDF/XML is the oldest RDF syntax • RDFa is new, integrates with XHTML • GRDDL lets you map from other XML or microformat notations • You can also map from SQL, JSON, CSV ...
    59. 59. Querying RDF: SPARQL • a language for asking questions • looks a lot like SQL, but simpler and webby • comes with xml and json Web service API • Working Group is working on an update
    60. 60. POWDER • let’s you say “everything on mp3.myserver.example.com/ is a CC-SA- licensed MP3 music file” • Or that “everything under w3.org/People/ is published by W3C” • Or that everything on images.playboy.com is an image that might not be child-suitable
    61. 61. SKOS • Simple Knowledge Organization Systems • An RDF-based way of encoding thesauri • Or other things that are thesaurus-like • Like site hierarchy, IMAP folders, tags • bringing lots of library data into the Web
    62. 62. Summary There’s a growing ecosystem around linked RDF data. Drupal can expect to manage files containing it, link to sites carrying it, and be populated with taxonomies expressed in it.
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