Help:Extension:Translate/Components

Translate extension is extensible in many ways. The most likely ways to extend Translate is to add support for new file formats (link to section) or new message groups (link to section). Sometimes it is also useful to write a new message checks (link to section) or to extend Translate via hooks (link to section). Sometimes you might get along only by using the existing web API.

In addition to the concepts already mentioned, there are many more important concepts and classes in Translate that are useful to understand when hacking Translate. This pages aims to comprehensively detail all components of Translate.

WebAPI

 * In-depth documentation at API

In addition to hooks and interfaces that can only be used from PHP code, the WebAPI provides access to many message group and translating related information and actions. It is based on the MediaWiki API framework, supporting many output formats like json and xml.

File format support (FFS)

 * In-depth documentation at X
 * List of supported file formats at X
 * Tutorial for writing FFS classes at X

The Translate extension supports translating of non-wiki content like software interface messages via File format support (FFS) classes. These classes implement the FFS interface and abstract away parsing and generating of file contents. The FFS classes are used by FileBasedMessageGroup class via the YAML configuration files.

Message groups
Message groups bring together a collection of messages. They come with a description and dictate the namespace where messages are stored, how can they be exported (usually via FFS) how are the definitions loaded (like from wiki pages, or via FFS) and other things.

Message group hierarchy
MessageGroupBase ! MessageGroupOld !
 * AggregateMessageGroup
 * FileBasedMessageGroup
 * SingleFileBasedMessageGroup
 * CoreMessageGroup
 * CoreMostUsedMessageGroup
 * ExtensionMessageGroup
 * AliasMessageGroup
 * WikiMessageGroup
 * RecentMessageGroup
 * SvgMessageGroup !!
 * WikiPageMessageGroup !!!
 * WorkflowStatesMessageGroup

! MessageGroupBase is the more recent base class. These groups are usually defined via the Yaml configuration, while the ones extending MessageGroupOld are defined in other ways. Core and extension message groups are for MediaWiki and are waiting to be migrated to FileBasedMessageGroup.

!! In TranslateSvg extension.

!!! Provides the page translation feature.

Main functions
Basic info. Each message group has an unique id (within a wiki), a label (short name) and a short description, than includes important information like licensing and link to page which has more information.

Namespace. All the definitions of messages and translations are placed in a namespace given by the message group. The file based message groups allow users to set the namespace, while other are hard coded to NS_TRANSLATIONS (page translation) or NS_MEDIAWIKI.

Checkers. Message groups can give a list of message checkers, that can warn the user. Common checks are for missing or unknown variables and invalid html.

Mangler. Each group has a message key mangler. It is mostly relevant only to file based message groups where the format of message keys cannot be enforced. See mangler section below.

Message loading. There are many methods for loading message definitions. The load method usually reads the messages from files via FFS class or from a database table. getDefinitions is a shortcut for loading the messages in the source language (see below).

Source language. All of the message definitions are expected to be in a single language. Only dynamic message groups like RecentMessageGroup can work around this limitation.

Tags. Messages can have tags. Tags ignored and optional are often used. In addition message collection provides its own additional tags.

Workflow states. Message groups can override the global workflow states.

Languages. By default all known languages can be translated into. The message groups can provide a subset of languages to disable translation in other languages.

Font finder
When rendering bitmap graphics, a suitable font is needed for a language. To solve this problem FCFontFinder class was written. It class the  command from fontconfig package (so this doesn't work on Windows) to find a suitable font. Many additional fonts should be installed on the server to make this useful. It can either return path to font file or the name of the font, whichever is more suitable.

Ttmserver (translation memory)

 * In-depth documentation at Translation memories.
 * Blog post of history of this feature at Niklas' blog.

Ttmserver is the name of translation memory interface. It supports multiple backends for inserting and querying translation suggestions. The code is located under  directory.