semantic web in action

Copyright 2007 Digital Enterprise Research Institute. All rights reserved. www.deri.org

Digital Enterprise Research Institute www.deri.ie

Semantic Web in Action

Stefan Decker, Eyal Oren, Sebastian R. Kruk

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Outline

Introduction about DERI Interlinking online communities: SIOC Application development: ActiveRDF &

BrowseRDF Sharing and interconnecting knowledge:

JeromeDL Summary

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DERI Galway – Mission

DERI Galway’s mission is “to exploit semantics for helping

– people– organisations– systems

to better collaborate and interoperate”.

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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

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“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)

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The Semantic Web (so far)

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Social semantic information spaces: SW 2.0

Web 2.0and socialsoftware



SIOC: Semantically Interlinked Community Sites

Stefan Decker

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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

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How can SIOC data be used?

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Browsing SIOC with TimeLine (1)

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Browsing SIOC with TimeLine (2)

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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?

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Next steps: Add Onion Rings of Vocabularies

RDF CalendarRDF Calendar

MicroformatsMicroformats



Semantic Web application development:

ActiveRDF and BrowseRDF

Eyal Oren

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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 systems Open systems

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Motivation

database

object-relational mapping

web application framework

relational web

applications:

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Motivation

database



relational web

applications:

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Motivation

database



relational web

applications:

semantic web applications:

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Motivation

database



data source

relational web

applications:


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Motivation

database



data sourceRDF store

relational web

applications:


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Motivation

database



???


???

relational web

applications:


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Motivation

database



???


???

relational web

applications:


ActiveRDF

Ruby on Rails

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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”.

Personname:string john: Person

name: “John Breslin”

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ActiveRDF examples

print names of john’s friends

find all 30-year olds named John

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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

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ActiveRDF object manager

Represents RDF resources (including RDFS classes) through 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

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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

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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

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Faceted browsing example: iTunes

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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

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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”.

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Selection operators

all thirty-year-olds all single people

all people who know somebody with a friend called Stefan

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Intersection operator

all single thirty-year-olds that know somebody who has a friend called Stefan

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Inverse operators

all DERI employees all working people

all people working for an Irish company

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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 ...

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Facet browsing: decision tree

faceted browsing: constructing & traversing decision tree

...

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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)

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SIOC explorer

Aggregate online community sources Dynamic faceted navigation Built on ActiveRDF and Ruby on Rails



JeromeDLthe Semantic Digital Library

Sharing and Interconnecting Knowledge

Sebastian R. Kruk

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Motivation

How to integrate and search information from different bibliographic sources?

How to share and interconnect knowledge among people?

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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

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Tomorrow 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

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Metadata and Services in JeromeDL

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Semantic Metadata and Services

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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

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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

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Browsing the data graph

JeromeDL exploits interconnected data

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Browsing the data graph

… to allow browsing

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Semantic Metadata and Services

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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)

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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

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foaf:knows

xfoaf:include

xfoaf:bookmark


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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

semantic web in action

Technology

web infrastructure

current web

sioc data

sioc application development

john foaf

sioc ontology

activerdf object manager

intuitive mapping