InterWiki

InterWiki is a way of facilitating the creation of links among the many WikiWiki sites on the Internet. Instead of requiring users to type or paste a complete URL to the wiki page on another wiki, they can use a shorthand notation. These notations vary, depending largely on what kind of link pattern a wiki uses. The two most common link patterns in wikis are CamelCase (words "SmashedTogether") and free links (words in [[double square brackets]]; see Wikipedia:Canonization).

Accordingly, InterWiki links on a CamelCase-based wiki frequently take the form of "Code:PageName", where Code is the defined name of another wiki. Thus, a link "WikiPedia:InterWiki" would be rendered in HTML as a link to this article. Linking to a page that contains spaces in it typically requires substitution of the spaces with underscores (e.g. WikiPedia:Main_Page).

InterWiki links on wikis based on free links typically follow the same principle, but the InterWiki code and page name are placed in double square brackets, which makes it simpler to link to pages with spaces in them. Example: [[Unreal:Map Design Concepts]].

Advantages

InterWiki makes it very easy to connect wikis on completely different subjects to each other, although the varying text formatting rules, layouts and link patterns complicate a seamless transition from one wiki to the next. Also, user accounts can typically not be re-used (most wikis do allow anonymous editing).

InterWiki has facilitated some initiatives to bring the different wikis closer together, such as wiki "bus tours" which a reader can take to learn about the purposes and highlights of different wikis (see Wikipedia:TourBusStop).

Implementation

From a technical perspective, a wiki that uses InterWiki needs to have an InterWikiMap that maps the wiki-code to the URL syntax, e.g.

[[WikiPedia:Main Page]]

needs to become

/wiki/Main_Page

While this looks like a simple search and replacement, it is complicated by the ways different URLs are structured and special characters are handled. These problems exist to a lesser degree in CamelCase-based wikis, where spaces cannot occur in titles.

The InterWiki map needs not be written anew for each wiki. The community wiki MeatballWiki has taken the initiative to publish an InterWiki map which can be used by other wikis with a similar syntax. Like all pages, the InterWiki map is openly editable, so that users can add their own wikis to the list. This ensures that the map is very up-to-date, but it may contain syntax errors that need to be fixed before use. To reduce this problem, UseModWiki (the wiki, not the software) also publishes an edited InterWiki map. That map is used by Wikipedia.

MeatballWiki uses a mechanism called "FileReplacement" to directly use the openly editable InterWiki map for its own pages. Changes to that map do not take effect immediately on MeatballWiki; instead, the configuration file that stores the InterWiki map is generated if the wiki page has been unedited for a defined period of time after the last edit. This delay is supposed to assure proper review of all changes to the map while not preventing open editing.

External links

• Publicly editable InterWiki map from MeatballWiki
• Editorially controlled InterWiki map from UseMod wiki (http://usemod.com/intermap.txt)
• Discussion of the InterWiki concept
• Discussion of the FileReplacement concept