Difference between revisions of "SemanticMediaWiki"

Revision as of 15:59, 24 December 2013

SemanticMediaWiki is a MediaWiki extension.

• Main purpose: Associate semantic properties with wiki pages, and various features based on it.
• Repository: https://github.com/mediawiki4intranet/SemanticMediaWiki
• Homepage: http://semantic-mediawiki.org, SemanticMediaWiki on mediawiki.org
• License: GPLv2.0+ 
• Created: 2006-08-22 
• Our rating: May be useful (3)

Status for Mediawiki4Intranet distribution:

• Inclusion date: 2012-12-12
• Included version: 2.3.x
• Improvement status: Forked in MediaWiki4Intranet with major improvements

Quality note

• SemanticMediaWiki is definitely a piece of bloated software, and it seems it becomes more bloated in new versions — 1.9 will contain a lot of refactoring, adding composer, multiple library dependencies, DI framework, unit tests (a religion which leads to refucking all the code)… and almost no new features.
• It seems almost nobody uses SMW for its original ideas (semantic web, rdf, ontologies and etc) — everyone just uses it to be able to add properties to pages, create something like «object model» using Wiki-programming and get something like «sql» using ask queries, which are ugly and inconvenient to use. And the properties are global, so you’ll also end up modeling «object classes».
• Summary: avoid massive usage of SMW if you can. Usually it leads to very ugly efforts of «wiki-programming». If you still have to use SMW, check out our improvements to it (see below).

Our improvements

• Query optimizer: identical subqueries are executed only once (for example, in <q>a OR b</q> <q>c OR d <q>a OR b</q></q> the «a OR b» part will be executed only once), identical terms are removed from conjunctions/disjunctions («a AND a», «a OR a» == just a)
• Conjunction-of-disjunctions execution bug fixed: in the original SMW, «(a OR b) AND (c OR d)» query was not executed at all! (test case: {{#ask: <q>[[A::B]] OR [[C::D]]</q> <q>[[E::F]] OR [[G::H]]</q> | format=debug }}). Patch sent to github: https://github.com/SemanticMediaWiki/SemanticMediaWiki/pull/19
• Negation operator support: syntax is {{#ask: [[prop::val]] !<q>...subquery...</q> }} or just {{#ask: [[prop::val]] ![[prop2::val2]] }}. Patch sent to github: https://github.com/SemanticMediaWiki/SemanticMediaWiki/pull/20
• Disable forced type-named properties: in the original SMW, data type aliases also have an unpleasant side-effect: if a property name matches the alias of some data type (for example «Telephone number») — the property will have that data type forced and you cannot override it. Patch sent to github: https://github.com/SemanticMediaWiki/SemanticMediaWiki/pull/21
• Automatic refresh of all pages with semantic queries on any property update — in the original SMW you have to manually refresh it every time. Of course this can lead to frequent cache flushes — even the queries that don’t use the updated property are flushed — but at least the user always gets correct query results.

Rough estimate for getting all this in trunk: never, or not any time soon. You have to push authors very hard to be able to submit something in SMW. I don’t want to do that.