Semantic search on heterogeneous wiki systems - Wikimania 2010

Digital Enterprise Research Institute www.deri.ie

Semantic Search on
Heterogeneous Wiki Systems

Fabrizio Orlandi, Alexandre Passant
DERI – Galway

Wikimania 2010
Gdansk – 10th July 2010
© Copyright 2009 Digital Enterprise Research Institute. All rights reserved.

Interlinking wikis

All wikis share a wide common knowledge, within many different
wiki platforms:

TWiki DokuWiki

MoinMoin

Widely used even in the workplace...

Atlassian Trac
XWiki
Confluence Wiki

All with different structures, platform dependent, all disconnected...

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Many isolated communities of users and their data

Wikis are also disconnected with other
social media websites

* Source: Pidgin Technologies, www.pidgintech.com

Interlinking wikis

We propose a new approach based on Linked Data principles to solve such
issues and to enable semantic search across heterogeneous wiki systems

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Wiki Models

Several semantic models have been implemented and used within
specific semantic wiki platforms

e.g.:

Semantic MediaWiki

as well as efforts to create generic ontology models:
•WikiOnt ontology (DERI)
•WIF (Wiki Interchange Format) ontology
(Völkel, Oren - 1st Workshop on Semantic Wikis - 2006)

But they are all specific to wikis and not open to other social
websites

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SIOC
Semantically-Interlinked Online Communities

• A project developed by DERI to semantically describe the content
and structure of community sites

• It aims to create new connections between online discussion posts
and items, forums, blogs... and wikis.

• In particular the SIOC ontology is not specific to wikis and is widely
used on the Web

• Adopted in a framework of more than 50 applications, deployed on
over 400 sites
including Drupal 7 and Yahoo! SearchMonkey

http://sioc-project.org

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Extending the SIOC ontology

We decided to extend the SIOC ontology to make it compliant with wikis
and make wikis interoperable and linkable to other social objects.

Advantages:
• Integration with all the existing semantic data
• Ability to run the same queries to find items on:
– wikis, forums, blogs, social neworking sites, etc.

First we considered the typical and relevant features of wikis in terms of
structure and social interactions.

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Relevant wiki features


Multi-authoring: multiple users edit the same content collaboratively.

• Categories: hierarchical organization of articles.
A solution: SKOS vocabulary (W3C recommendation to model hierarchical structures between various
categories) and the sioct:Category class

• Social Tagging: non-organized but dynamic organization process.
The properties sioc:topic (using URIs) and dc:subject (using keywords) can be used to represent tags
related to a particular wiki page.

http://wiki.../The_Clash sioc:topic
http://wiki.../Punk_rock

dc:subject tag:hasTag

Punk rock

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Relevant wiki features

• Discussions: pages where people can discuss about the article subject.
We added a new sioc:has_discussion property, with domain sioc:Item and open range.

• Backlinks: (or “what links here”) wiki internal links pointing to the same wiki article.
We use the already existing sioc:links_to property.


Pages Versioning: each page has an associated page history.

We use sioc:next(previous)_version and sioc:latest_version properties.

Added 2 transitive (OWL) properties: sioc:earlier_version & sioc:later_version;

Defined sioc:next(previous)_version as subproperties of sioc:later(earlier)_version.

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SIOC-MediaWiki Exporter

An exporter from a popular wiki platform to expose data in RDF using our
proposed model.

A webservice, written in PHP, that exports a MediaWiki article in RDF publicly
available at:
http://ws.sioc-project.org/mediawiki/

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SIOC-MediaWiki Exporter

An exporter from a popular wiki platform to expose data in RDF using our
proposed model.

A webservice, written in PHP, that exports a MediaWiki article in RDF publicly
available at:
http://ws.sioc-project.org/mediawiki/

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Browsing the generated data

RDF data extracted from a wiki page is browsable with tools such as
The Tabulator

To offer a better browsing experience and ease the process of
crawling SIOC exports of MediaWiki instances, the webservice
automatically produces rdfs:seeAlso links between wiki pages,
following the Linked Data practices;

Link to the corresponding Dbpedia resource added automatically, if
the article is from the Wikipedia [English] (with foaf:primaryTopic)
A RDF crawler can easily follow all the seeAlso links found on every
document and continue to crawl, so it is possible to crawl an entire
wiki site starting from a single URI.

Browsing the generated data

RDF data extracted from a wiki page is browsable with tools such as
The Tabulator

The webservice automatically produces rdfs:seeAlso links between
wiki pages, following the Linked Data principles;

A RDF crawler can easily follow all the seeAlso links found on every
document and continue to crawl, so it is possible to crawl an entire
wiki site starting from a single URI.

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The DokuSIOC plugin


A plugin for DokuWiki that exports RDF data using popular lightweight ontologies
(originally developed by M. Haschke, a SIOC contributor).


We modified and extended this plug-in in order to be compliant with our proposed
model and to export all the needed wiki features.


It takes information from the metadata stored in the wiki system about pages,
users, links, etc. and provides it as raw RDF/XML serialized data
(instead of the usual HTML page).


Developed in PHP and easy to install in every DokuWiki system.


It uses the SIOC PHP API.

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The DokuSIOC plugin

Collecting Data

To evaluate our proposal, we exported and crawled 5 different
MediaWiki and DokuWiki instances
Collecting more than: 1GB of RDF data,
3000 wiki articles and 700 users
Data loaded in a triple-store (Sesame + OWLIM)
On the top of that it is possible to run cross-sites queries
by combining FOAF and SIOC
e.g.:

SELECT DISTINCT ?content
WHERE {
<http://example.org/js#me> foaf:account ?account .
?account rdf:type sioc:UserAccount .
?content sioc:has_creator ?account .
}

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Collecting Data

SELECT DISTINCT ?content
WHERE {
<http://example.org/js#me> foaf:account ?account .
?account rdf:type sioc:UserAccount .
?content sioc:has_creator ?account .
}

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Building the application


The data acquisition module is a PHP script that:

queries the triple-store

collects and parses the results

translates the data in the correct format (JSON) for the visualization
layer


The visualization layer has been built with the Exhibit framework by the
MIT SIMILE Project

It is a set of Javascript files directly configurable on the HTML code of
the page to display

It allows for faceted browsing capabilities

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Conclusions


Presented how the SIOC ontology and lightweight semantics can be
used and extended to represent the structure of wikis;


How to interlink wikis to other online communities;


Demonstrated an overall benefit on applying SemWeb technologies
to wikis:
– enabling end-users to access the information generated in a
simple and transparent way,
– showing potentialities that cannot be obtained using the traditional
Web 2.0 instruments;

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Thank you!

Any questions?

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Semantic search on heterogeneous wiki systems - Wikimania 2010

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