by Fabrizio Orlandi and Alexandre Passant. Presented @ 4th Semantic Wiki Workshop, ESWC 2009.

1. Enabling cross-wikis integration by
extending the SIOC ontology
SemWiki 2009 – ESWC Fabrizio Orlandi1
(June 1, 2009) Alexandre Passant2
1 Università di Modena e Reggio Emilia
2 Digital Enterprise Research Institute, Galway

2. Interlinking wikis
All wikis share a wide common knowledge, but they have
different structures and implementations, platform dependent.
TWiki DokuWiki
MoinMoin
There are lots of wikis and they are all disconnected...

3. Many isolated communities of users and their data
Wikis are also disconnected with other
social media websites
* Source: Pidgin Technologies, www.pidgintech.com

4. Interlinking wikis
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 (Max Völkel et al.)
)
But they are all specific to wikis and not open to other social websites

5. SIOC
Semantically-
Semantically-Interlinked Online Communities
• A project developed by DERI to semantically describe the content and
structure of community sites
• In particular the SIOC ontology is not specific to wikis and is widely used
on the Web
• It aims to create new connections between online discussion posts and
items, forums, blogs... and wikis.
• Adopted in a framework of more than 50 applications,
deployed on over 400 sites
http://sioc-
http://sioc-project.org

6. 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.
objects.
First we considered the typical and relevant features of wikis in terms of
structure and social interactions.
interactions.
Modeling these features using SIOC would have other advantages:
advantages:
• Integration with existing SIOC data, as well as interlinking with other
RDF data for advanced querying purposes;
purposes;
•Ability to run the same SPARQL query to find items on a particular wiki
site or on a weblog or a forum.
forum.

7. Relevant wiki features
• Multi-authoring: multiple users edit the same content simultaneously.
Multi- simultaneously.
Feature modeled using the class sioc:User (subclass of foaf:OnlineAccount as
foaf:OnlineAccount)
object of sioc:has_creator that describes a user account in an online community
site.
In this way a foaf:Person can be linked to several sioc:User belonging to different
wiki sites.

8. Relevant wiki features
• Categories:
Categories: sets of articles on related topics which are hierarchically
organized.
organized.
A solution is provided by the SKOS vocabulary, as it offers a way to model
hierarchical structures between various categories, as instances of skos:Concept.
skos:Concept.
Hence we defined the sioct:Category class as a subclass of skos:Concept.
sioct: skos:Concept.

9. Relevant wiki features
• Social Tagging: non-organized but dynamic organization process.
Tagging: non- process.
The properties sioc:topic (using URIs) and dc:subject (using keywords) can be
sioc: dc:
used to represent tags related to a particular wiki page.
page.
http://wiki.../The_Clash sioc:topic http://wiki.../punk_rock
dc:subject tag:hasTag
Punk rock

10. Relevant wiki features
• Discussions: pages where people can discuss about the article subject.
Discussions: subject.
We added a new sioc:has_discussion property, with domain sioc:Item and open
range (to make this property reusable).

11. Relevant wiki features
• Backlinks: (or “what links here”) wiki internal links pointing to the same
Backlinks: here”)
wiki article.
article.
We modeled this feature using the already existing sioc:links_to property
sioc:
(subproperty of dcterms:references).
dcterms:references)

12. Relevant wiki features
• Pages Versioning: each page has an associated page history.
In order to define an essential and lightweight model we:
• Added a sioc:latest_version property;
• Added 2 transitive properties: sioc:earlier_version & sioc:later_version;;
• Defined sioc:later_version as inverse property of sioc:earlier_version;;
• Defined sioc:next(previous)_version as subproperty of sioc:later(earlier)_version.
.

13. SIOC-
SIOC-MediaWiki Exporter
An exporter from a popular wiki platform to expose data in RDF using our
proposed model.
model.
A webservice, written in PHP, that exports a MediaWiki article in RDF, publicly
available at:
at:
http://ws.sioc-
http://ws.sioc-project.org/mediawiki/

14. SIOC-
SIOC-MediaWiki Exporter
An exporter from a popular wiki platform to expose data in RDF using our
proposed model.
model.
A webservice, written in PHP, that exports a MediaWiki article in RDF, publicly
available at:
at:
http://ws.sioc-
http://ws.sioc-project.org/mediawiki/

15. 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
instances,
rdfs:seeAlso links between wiki pages, following the Linked Data practices;
rdfs: pages, practices;
Link to the corresponding Dbpedia resource added automatically, if the
article is from the Wikipedia [English] (with foaf:primaryTopic)
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.

16. 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
instances,
rdfs:seeAlso links between wiki pages, following the Linked Data practices;
rdfs: pages, practices;
Link to the corresponding Dbpedia resource added automatically, if the
article is from the Wikipedia [English] (with foaf:primaryTopic)
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.

17. Advanced querying process
To evaluate our proposal, we exported and crawled different MediaWiki
proposal,
instances:
instances: 4 wikis have been crawled, collecting more than 1GB of RDF data.
crawled,
RDF data loaded in a triple-store: Sesame + OWLIM
triple-store:
SPARQL queries for a single wiki:
wiki:
”what are the collaborating users that worked alternatively on the same wiki
article?”
article?”
SELECT DISTINCT ?wikiArt ?Contrib_a ?Contrib_b
WHERE {
?x sioc:latest_version ?wikiArt .
?wikiArt sioc:earlier_version ?VersA .
?VersA sioc:earlier_version ?VersB ;
dc:contributor ?Contrib_a .
?VersB sioc:earlier_version ?VersC ;
dc:contributor ?Contrib_b .
?VersC dc:contributor ?Contrib_a .
FILTER (?Contrib_a != ?Contrib_b ) . }

18. Advanced querying process
SPARQL cross-wikis querying
cross-
”Identify pages created by the same user between different wikis”:
SELECT DISTINCT ?creator1 ?page1 ?page2 ?wiki1 ?wiki2
WHERE {
?page1 sioc:has_container ?wiki1 ;
dc:contributor ?creator1 .
?page2 sioc:has_container ?wiki2 ;
dc:contributor ?creator2 .
FILTER ( str ( ?creator1 ) == str ( ?creator2 ) ) .
FILTER ( str ( ?wiki1 ) != str ( ?wiki2 ) ) . }
”Cross-sites querying by combining FOAF and SIOC”:
Cross-
SELECT DISTINCT ?content
WHERE {
<http://example.org/js#me> foaf:holdsAccount ?account .
?account rdf:type sioc:User .
?content sioc:has_creator ?account .
}

19. Conclusion
Overview:
Presented how the SIOC ontology and lightweight semantics can be used
and extended to represent the structure of wikis in an unified way;
Described how we designed a webservice to translate any MediaWiki page
into SIOC data, following the Linked Data best principles;
Provided examples on how this data could be efficiently used for querying
purposes.
What's next?
Further developments may include exporters and plug-in for other
plug-
platforms to enable better cross-wikis integration;
cross-
To extend the pages versioning system defined in SIOC regarding wikis to
other user-generated content;
user-
The modeling of a wiki page might be improved adding more details about
the content of the article itself.

20. Thank you!
Any questions?