Interface messages on MediaWiki and its many extensions are translated into more than 350 languages on Thousands of translations are created or updated each day. Usually, users of a wiki would have to wait until a new version of MediaWiki or of an extension is released to see these updated translations. However, webmasters can use the LocalisationUpdate extension to fetch and apply these translations daily without having to update the source code.

LocalisationUpdate provides a command line script to fetch updated translations. It can be run manually, but usually it is configured to run automatically using cron jobs. The sequence of events that the script follows is:

  1. Gather a list of all localisation files that are in use on the wiki.
  2. Fetch the latest localisation files from either:
    • an online source code repository, using https, or
    • clones of the repositories in the local file system.
  3. Check whether English strings have changed to skip incompatible updates.
  4. Compare all translations in all languages to find updated and new translations.
  5. Store the translations in separate localisation files.

MediaWiki’s localisation cache will automatically find the new translations via a hook subscribed by the LocalisationUpdate extension.

Until very recently the localisation files existed in PHP format. These are now converted to JSON format. This update required changes to be made in LocalisationUpdate to handle JSON files. Extending the code piecemeal over the years had made the code base tough to maintain. The code has been rewritten with extensibility to support future development as well as to retain adequate support for older MediaWiki versions that use this extension.

The rewrite did not add any new features except support for JSON format. The code for the existing functionality was refactored using modern development patterns such as separation of concerns and dependency injection. Unit tests were added as well.

The configuration format for the update scripts changed, but most webmasters won’t need to change anything, and will be able to use the default settings. Changes will be needed only on sites that for some reason don’t use the default repositories.

New features are being planned for future versions that would optimise LocalisationUpdate to run faster and without any manual configuration. Currently, the client downloads the latest translations for all extensions in all languages and then compares which translations can be updated. By moving some of the complex processing to a separate web service, the client can save bandwidth by downloading only updated messages for specific updated languages used by the reader.

There are still more things to improve in LocalisationUpdate. If you are a developer or a webmaster of a MediaWiki site, please join us in shaping the future of this tool.

Niklas Laxström and Runa Bhattacharjee, Language Engineering, Wikimedia Foundation