Semantic Web in Action
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This is the presentation we (Stefan, Eyal, and I) gave to Google on May, 25th 2007

This is the presentation we (Stefan, Eyal, and I) gave to Google on May, 25th 2007

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Semantic Web in Action Semantic Web in Action Presentation Transcript

  • Semantic Web in Action Stefan Decker, Eyal Oren, Sebastian R. Kruk
  • Outline
    • Introduction about DERI
    • Interlinking online communities: SIOC
    • Application development: ActiveRDF & BrowseRDF
    • Sharing and interconnecting knowledge: JeromeDL
    • Summary
  • DERI Galway – Mission
    • DERI Galway’s m ission is “to exploit semantics for helping
        • p eople
        • o rganisations
        • s ystems
    • to better collaborate and interoperate”.
  • Some statistics
    • Founded June 2003 with 1 fulltime member
    • Status May 2007: 98 members
    • Core fulltime research active members:
      • 2 Professors
      • 6 additional senior scientific researchers
      • 9 PostDocs
      • 5 Research Staff
      • 58 PhD, Master Students & Interns
    • 18 members are administration & management, industry and community outreach, university liaison, subcontractors
    • Still hiring aggressively
      • “ An extension of the current Web in which information is given well-defined meaning, better enabling computers and people to work in cooperation.”
        • Sir Tim Berners-Lee et al., Scientific American, 2001: tinyurl.com/i59p
      • “… allowing the Web to reach its full potential…” with far-reaching consequences
      • “ The next generation of the Web”
    What is the Semantic Web? (beware the hype)
  • The Semantic Web (so far)
  • Social semantic information spaces: SW 2.0 Web 2.0 and social software
  • SIOC: Semantically Interlinked Community Sites Stefan Decker
  • What is SIOC?
    • Semantically-Interlinked Online Communities (SIOC)
    • Connecting many types of online communities (blogs, forums, mailing lists, etc.)
    • Interesting possibilities:
      • Distributed linked conversations
      • Decentralised discussion channels and communities
    • “ I […] think the concept is HOT” – Robert Douglass, Drupal Developer
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  • SIOC Ontology
  • How can SIOC data be used?
  • Browsing SIOC with TimeLine (1)
  • Browsing SIOC with TimeLine (2)
    • Create SIOC export modules for popular open-source discussion systems
    • Infecting the Web Infrastructure:
      • During next upgrade cycle gigabytes of community data become available
    • SIOC metadata exporters created for:
      • Content management system (Drupal)
      • Bulletin board system (phpBB)
      • Blogging system (WordPress)
      • French blogging system (DotClear)
    How can SIOC disseminated?
  •  
  • Next steps : Add Onion Rings of Vocabularies RDF Calendar Microformats
  • Semantic Web application development: ActiveRDF and BrowseRDF Eyal Oren
  • Semantic Web applications: Database-driven web applications Semantic Web applications Centralised Decentralised One fixed schema Semi-structured One fixed vocabulary Arbitrary vocabulary Centralised publishing Publish anywhere One datasource Many distributed datasources Closed system s Open systems
  • Motivation relational web applications: database object-relational mapping web application framework
  • Motivation relational web applications: database object-relational mapping web application framework
  • Motivation relational web applications: semantic web applications: database object-relational mapping web application framework
  • Motivation relational web applications: semantic web applications: database object-relational mapping web application framework data source
  • Motivation relational web applications: semantic web applications: database object-relational mapping web application framework data source RDF store
  • Motivation relational web applications: semantic web applications: database object-relational mapping web application framework ??? data source RDF store ???
  • Motivation relational web applications: semantic web applications: database object-relational mapping web application framework ??? data source RDF store ??? ActiveRDF Ruby on Rails
  • ActiveRDF: RDF(S) to OO mapping
    • Intuitive mapping:
      • RDF(S) classes to OO classes
      • RDF resources to OO objects
      • RDF triples to OO attribute values
    foaf:Person a rdfs:Class. john a foaf:Person. john foaf:name “John Breslin”. Person name:string john: Person name: “John Breslin”
  • ActiveRDF examples
    • print names of john’s friends
    • find all 30-year olds named John
  • ActiveRDF architecture proxy objects represent RDF resource, convert methods into queries abstract query API manages collection of data sources wraps RDF store with its own API
  • ActiveRDF object manager
    • Represents RDF resources (including RDFS classes) t hrough proxy objects
    • Intercepts each method call, converts method call into read/write query
    • Intercepts all dynamic finders calls, converts into query
    • print john.foaf::name
    • john.foaf::knows << jack
    • FOAF::Person.find_all
  • ActiveRDF adapters
    • Abstract RDF (or other) data into homogeneous API
    • SPARQL endpoints, Sesame, Jena, YARS, Redland, ...
    • Application data (e.g. Evolution emails)
    • Desktop metadata (e.g. Apple Spotlight metadata)
    • Reuse ActiveRDF framework with arbitrary data sources
  • Problems with intuitive mapping
    • RDF Schema ≠ OO class definition
      • OO: class membership determines instance behaviour
      • RDF(S): instance behaviour determines class membership
      • several consequences, e.g. RDF(S) properties propagate upwards
    • See (Oren et al., WWW2007) for details and solutions
  • Faceted Navigation for RDF Data
  • Faceted browsing example: iTunes
  • Faceted browsing: limitations
    • facets manually configured for a fixed domain
      • music: genre, artist, album, title
      • books: title, author, publisher
      • recipes: ingredients, cuisine, calories, preparation time
    • facets do not (fully) exploit interconnected data
      • assume data homogeneity
      • focus on one resource type (e.g. songs )
      • only facets of songs , not of singers, albums, publishers
  • Faceted browsing on the Semantic Web
    • faceted browsing is query construction
    • facets in semantic web data:
      • information space: set of triples
      • elements of interest: set of subjects
      • facets: set of properties
    • now identify operators ...
    SELECT ?x WHERE ?x author ?a and ?a age “30”.
  • Selection operators all thirty-year-olds all single people all people who know somebody with a friend called Stefan
  • Intersection operator all single thirty-year-olds that know somebody who has a friend called Stefan
  • Inverse operators all DERI employees all working people all people working for an Irish company
  • Interface construction algorithm select resources (constrain information space) select facets (arcs in constrained space) rank facets (identify most interesting facets) select ?s where ... select ?p where ...
  • Facet browsing: decision tree
    • faceted browsing: constructing & traversing decision tree
    ...
  • Facet ranking: optimise decision tree
    • decision tree affects navigation efficiency
    • cardinality
      • author: 300 values (all names unique)
      • publisher: 5 values (only few topics)
    • balance
      • publisher: Springer (82%), rest (18%)
      • topic: logic (30%), p2p (30%), web (40%)
    • frequency
      • location 5% (almost never given)
      • author 100% (no anonymous publications)
  • SIOC explorer
    • Aggregate online community sources
    • Dynamic faceted navigation
    • Built on ActiveRDF and Ruby on Rails
  • JeromeDL the Semantic Digital Library Sharing and Interconnecting Knowledge Sebastian R. Kruk
  • Motivation
    • How to integrate and search information from different bibliographic sources?
    • How to share and interconnect knowledge among people?
  • Yesterday ’s world of digital content
    • Digital library
      • Database and archive (storage)
      • Digital bibliographic descriptions (metadata)
      • Full-text search (interface)
    • Pros:
      • Content accessible online
      • Federations of libraries – visit less places
    • Cons:
      • Lonely user
      • No one to talk to, we need to find the right keywords, what if we do not know them (“man without an ear” paintings example)
      • Still many problems with interconnecting (different) libraries
  • To morrow of interconnected , social media
    • Social Semantic Information Spaces
      • Semantic description (interconnected metadata)
      • Annotations provided by users (social metadata)
      • Collaborative search and browsing (interface)
    • Features
      • Search and browsing based on semantics empowers users
      • Users contribute to the classification process
      • Users can understand community driven annotations
      • Users enhance digital content using blogs, wikis on the side
      • RDF provides bases for interconnection of digital libraries
  • JeromeDL - Properties
    • Support for different kinds of metadata (DublinCore, BibTeX, MARC21)
    • Supporting users and communities :
      • users have control over their profile information;
      • community-aware profiles integrated with bibliographic descriptions
      • support for community-generated knowledge
  • Metadata and Services in JeromeDL
  • Semantic Metadata and Services
  • Browsing the data graph – why?
    • The search does not end on a (long) list of results
    • The results are not a list (!) but a graph
    • „ Lost in hyperspace”
    • A need for unified UI and services for filter/narrow and browse/expand services
    • Share browsing experience – navigate collaboratively
  • Browsing the data graph – how?
    • Defines REST access to services and their composition
    • Basic services: access, search, filter, similar, browse, combine
    • Meta services : RDF serialization, subscription channels, service ID generation ,
    • Context services : manage contexts, manage service calls/compositions in the context, lists contexts
    • Statistics services : properties, values, tokens
  • Browsing the data graph
    • JeromeDL exploits interconnected data
  • Browsing the data graph
    • … to allow browsing
  • Semantic Metadata and Services
  • Social Semantic Collaborative Filtering
    • Why?
      • The bottom-line of acquiring knowledge: informal communication (“word of mouth”)
    • How?
      • Everyone classifies (filters) the information in bookmark folders (user-oriented taxonomy)
      • Peers share (collaborate over) the information (community-driven taxonomy)
    • Result?
      • Knowledge “flows“ from the expert through the social network to the user
      • System amass a lot of information on user/community profile (context)
  • Social Semantic Collaborative Filtering
    • Problems?
      • The horizon of a social network (2-3 degrees of separation)
      • How to handle fine-grained information (blogs, wikis, etc.)
    • Solutions?
      • Inference engine to suggest knowledge from the outskirts of the social network
      • Support for SIOC metadata :
        • SIOC browser in SSCF
        • Annotations and evaluations of “local” resources
  • Social Semantic Collaborative Filtering foaf:knows xfoaf:include xfoaf:bookmark
  • Summary
    • Some of DERI’s open-source SemWeb technology:
      • Online communities metadata: SIOC http://sioc-project.org
      • Data mapping: ActiveRDF http://activerdf.org
      • Semantic Content Repository: JeromeDL http://jeromedl.org
      • Faceted navigation: BrowseRDF, MultiBeeBrowse http://browserdf.org
      • Social knowledge sharing: SSCF http://s3b.corrib.org
    • Much more: http://deri.ie