MediaWiki
MediaWiki is currently the most used open source wiki software. Developed and maintained by WikiMedia Foundation, it is a robust and highly scalable system that is efficient enough to be used as the engine that runs Wikipedia, one of the most frequently visited sites on the World Wide Web.
Wikipedia.org entry for MediaWiki
Installation Requirements
MediaWiki requires a web server running:
- PHP 5.2.3 or greater
- MySQL 5.0.2+, PostgreSQL, or SQLite
MediaWiki is also available pre-installed via many Wiki Farm hosting services.
Ease of installation/use
Provided you are relatively familiar with webserver backend administration, the MediaWiki install should present no great problems. Once the files are uploaded via FTP to the desired location on the webserver, a configuration PHP page is run, letting you set some very basic options. You will need to know your username and password for the SQL server you run. Once you have filled out these details, your site is now ready to go. Further configuration will require you to manually edit the LocalSettings.php file (to change the location of your logo image, for instance).
When it comes to creating and editing pages on your new site, you will need to be familiar with the Wikitext Syntax. While it is relatively easy to get a handle on, if you do plan on having other authors contribute to the site my own experience is that for a lot of people, Wiki Language is not as simple to learn as is often claimed, particularly when authors attempt more complicated markup like tables or lists. Your mileage may vary.
IA Considerations
MediaWiki scores very well when considering information architecture principles. The basic structure of the site uses a well known three column + header and footer design pattern, and the popularity of Wikipedia ensures that most visitors will probably understand 'how the site works' at first glance. The default installation provides a main menu in the left hand column which is easily editable in the same manner one would edit any MediaWiki page (though an administrator login is required).
The search engine used in the CMS is very effective out of the box and provides IA "niceties" such as search prediction and a "did you mean" feature for unsuccessful searches. Grouping of results is also possible though this is limited usefully to mostly "Content Pages" (the default), and "Multimedia". It would be interesting to see MediaWiki allow for Manual grouping based on Metadata (Morville & Rosenfeld, 2007, p. 175), such as topic or audience.
Categories are an interesting feature of the MediaWiki software that somewhat address the problems associated with folksonomy systems such as free-for-all tagging. Wiki code can be added (usually at the bottom, but this is not enforced) that denotes a page as belonging to a certain category, and tables of contents can then be automatically generated from these categories. Categories can also be placed inside categories, allowig for a heirarchy of subjects and more ability to control that heirarchy, somewhat more like a traditional classification system.