Semantic Web in Action

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

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: 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

Semantic Web in Action

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