| Developer(s) | various |
|---|---|
| Stable release | 1.7.0 / January 1, 2012 |
| Written in | PHP |
| Operating system | Cross-platform |
| Type | MediaWiki extension |
| License | GPL |
| Website | http://www.semantic-mediawiki.org/ |
Semantic MediaWiki (SMW) is an extension to MediaWiki that allows for annotating semantic data within wiki pages, thus turning a wiki that incorporates the extension into a semantic wiki. Data that has been encoded can be used in semantic searches, used for aggregation of pages, displayed in formats like maps, calendars and graphs, and exported to the outside world via formats like RDF and CSV.
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Semantic MediaWiki was initially created by Markus Krötzsch, Denny Vrandečić and Max Völkel, and was first released in 2005. Its development was initially funded by the EU-funded FP6 project SEKT, and was later supported in part by Institute AIFB of the University of Karlsruhe (later renamed the Karlsruhe Institute of Technology). Krötzsch remains the lead developer as of 2011, while other core developers are Jeroen De Dauw and Yaron Koren.[1]
Every semantic annotation within SMW is a "property" connecting the page on which it resides to some other piece of data, either another page or a data value of some type, using triples of the form "subject, predicate, object".
As an example, a page about Germany could have, encoded within it, the fact its capital city is Berlin. On the page "Germany", the syntax would be:
... the capital city is [[Has capital::Berlin]] ...
which is semantically equivalent to the statement "Germany" "Has capital" "Berlin". In this example the "Germany" page is the subject, "Has capital" is the predicate, and "Berlin" is the object that the semantic link is pointing to.
However, the much more common way of storing data within Semantic MediaWiki is via MediaWiki templates which themselves contain the necessary SMW markup. For this example, the "Germany" page could contain a call to a template called "Country", that looked like this:
{{Country
...
|Capital=Berlin
...
}}
The "Country" template would handle storing whatever the value of the parameter "Capital" is, using the property "Has capital". The template would also handle the display of the data. Semantic MediaWiki developers have estimated that 99% of SMW data is stored in this way.[2]
Semantic MediaWiki also has its own inline querying tools. For instance, if pages about countries stored additional information like population data, a query could be added to a page that displays a list of all countries with a population greater than 50 million, along with their capital city; and Germany would appear in such a list, with Berlin alongside it.[3]
Semantic MediaWiki is in use on over 250 public active wikis around the world, in addition to an unknown number of private wikis.[4][5] Notable public wikis that use SMW include the Metacafe wiki, SNPedia, SKYbrary, Metavid, Familypedia, OpenEI,[6] the Free Software Directory and Break.com's Chickipedia.[7][8] Organizations that use SMW internally include Pfizer,[9] Harvard Pilgrim Health Care,[10] Johnson & Johnson Pharmaceutical Research and Development,[11] the Pacific Northwest National Laboratory,[12] the Metropolitan Museum of Art[13] and the U.S. Department of Defense.[14]
SMW has notably gained traction in the health care domain for collaboratively creating bio-medical terminologies and ontologies.[15] Examples are LexWiki,[16] which is jointly run by the Mayo Clinic, National Cancer Institute, World Health Organization and Stanford University; Neuroscience Information Framework's NeuroLex; and the Concept Hub wiki,[17] operated by 3M Health Information Systems.
Semantic MediaWiki is also supported on at least two wiki farm websites: Referata[18] by default,[19] as well as Wikia on user request.
Some members of the academic community have been urging the use of SMW on Wikipedia since SMW was first proposed.[20] In a 2006 paper, Max Völkel et al. wrote that in spite of Wikipedia's utility, "its contents are barely machine-interpretable. Structural knowledge, e.g. about how concepts are interrelated, can neither be formally stated nor automatically processed. Also the wealth of numerical data is only available as plain text and thus can not be processed by its actual meaning."[21]
In a 2010 Technology Review online article, Wikimedia Foundation Deputy Director Erik Möller was quoted as saying that Wikimedia was interested in adding semantic capabilities to Wikipedia, but that they were unsure whether Semantic MediaWiki was the right solution, since it was unclear whether it could be used without negatively affecting Wikipedia's performance.[22]
A variety of open-source MediaWiki extensions exist that use the data structure provided by Semantic MediaWiki.[23] Among the most notable are:
The official gathering for Semantic MediaWiki developers and users is SMWCon, which has been held twice a year since 2010, in Cambridge, Massachusetts, Amsterdam, Arlington, Virginia and Berlin.[24] Each event has drawn around 30-40 attendees.
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