Creating language packs for extensions in Joomla 1.6/1.7

Although Joomla 1.6 supports installing language files for the front end (site) or back end (admin), it has no dedicated way to install language files for extensions (components, plugins, modules) unless they are installed with the extension itself.

Fortunately, Joomla 1.6 supports a powerful way to install an arbitrary set of files called a 'files' installation unit. (See Installation unit for an arbitrary set of files named 'files_test1').

Example Plugin Language Pack

Suppose you have a content plugin named 'alpha' that you want to create a new language pack for language zz-ZZ. Here is what your language pack files in the folder 'alpha_zz_zz_language_pack' might look like:

── alpha_zz_zz_language_pack
   ├── index.html
   ├── alpha.xml
   ├── zz-ZZ.plg_content_alpha.ini
   └── zz-ZZ.plg_content_alpha.sys.ini

where the file 'alpha.xml' is the installation manifest file. it would look something like this:

   <?xml version="1.0" encoding="utf-8"?>
   <extension version="1.7" type="file" method="upgrade">
     <name>alpha_zz_zz_language_pack</name>
     <version>1.6</version>
     <creationDate></creationDate>
     <author></author>
     <authorEmail></authorEmail>
     <authorUrl></authorUrl>
     <copyright>Copyright (C) 2011 ???. All rights reserved.</copyright>
     <license>http://www.gnu.org/licenses/gpl-2.0.html GNU/GPL</license>
     <description>ALPHA_ZZ_ZZ_LANGUAGE_PACK</description>
     <fileset>
       <files target="plugins/content/alpha/language/zz-ZZ">
         <filename>index.html</filename>
         <filename>zz-ZZ.plg_content_alpha.ini</filename>
         <filename>zz-ZZ.plg_content_alpha.sys.ini</filename>
       </files>
       <files folder="language/en-GB" target="language/en-GB">
         <filename>en-GB.files_alpha_zz_zz_language_pack.sys.ini</filename>
       </files>
       <files folder="language/zz-ZZ" target="language/zz-ZZ">
         <filename>zz-ZZ.files_alpha_zz_zz_language_pack.sys.ini</filename>
       </files>
     </fileset>
   </extension>