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This is a high-level overview of MediaWiki development, including links to the key documents, resources and tools available to MediaWiki developers. It is written for skilled LAMP developers who have experience using MediaWiki.

For an introductory guide to developing MediaWiki, read how to become a MediaWiki hacker. If you want to understand how to use a part of MediaWiki (e.g. the Job Queue) see the developer's FAQ

For help installing or customizing MediaWiki, visit the Sysadmin hub. For help using MediaWiki, visit the User hub.

Developer news

• 2011-08-29 MediaWiki core, extension, gadget, template, and tools developers invited to New Orleans hackathon to take place 14-16 October 2011.
• 2011-06-22 MediaWiki 1.17.0 has been released.
• 2011-04-25 2011 Google Summer of Code student projects announced.
• 2011-01-07 Extension developers whose extensions use JavaScript should implement ResourceLoader support in their extensions. Read the ResourceLoader crash course to get started.
• 2010-12-07 MediaWiki 1.17 branched

Read older news

Overview

MediaWiki is developed in an open source style using the PHP programming language primarily for the LAMP platform. Core development is largely coordinated online:

• development discussion happens on various mailing lists and IRC channels. The main developer list is wikitech-l. The main developer IRC channel is #mediawiki. Read the Developers article to get a sense for who the people on the mailing lists and IRC channels are.
• The MediaWiki roadmap shows rough information about when major development work is scheduled.
• bugs are managed using Bugzilla at bugzilla.wikimedia.org. The Bugs article has an overview of how the MediaWiki developers manage bugs.
• security issues are reported to [email protected]. Read article Security for more information.
• code review is facilitated using the CodeReview MediaWiki extension at Special:Code/MediaWiki and follows the code review guidelines.
• source code is managed using the Subversion revision control system. Read the Subversion article for an overview of how the MediaWiki developers use Subversion. Read the Commit access article if you'd like commit access.
• documentation for developers is maintained in the Manual namespace on this wiki. A file and class reference (which is generated from the MediaWiki source code using doxygen) can be found at http://svn.wikimedia.org/doc.
• developers extending or interfacing with MediaWiki (instead working on the core code) have several convenient extension points, including the API, the Hooks system and Skins – see the #Extending MediaWiki section of this page for an overview.

Key documents

Code, development and style Development policy – an overview of key development policies. Coding conventions – learn how to write PHP code in the MediaWiki style. Security for developers – learn how to help keep MediaWiki secure. Pre-commit checklist – review this checklist before committing code. Code review guide – a guide reviewing commits to the MediaWiki source code. Commit access – instructions on requesting commit access and committing code.

Debugging and testing Bugs – an overview of bug tracking in the MediaWiki project. How to debug – a guide to debugging MediaWiki. Manual:Errors and Symptoms – an overview of common MediaWiki errors and their correlating symptoms. Selenium Framework – learn to write UI tests for MediaWiki using Selenium. Unit testing – learn to write unit tests for MediaWiki using PHPUnit.

Architecture Manual:Code – an overview of the key parts of MediaWiki's source code. Database layout – an overview of MediaWiki's database schemas. Global object variables – a partial list of key global variables. Localisation – learn about MediaWiki's internationalization system. MediaWiki Class Reference – technical documentation generated from the MediaWiki source code. (Note: The class reference is a large, slow-to-load page.)

Sub-systems API – MediaWiki's API provides direct, high-level access to the data contained in the MediaWiki databases. Database access – an overview of using databases in MediaWiki, including a brief guide to the database abstraction layer. Documentation MediaWiki Virtual Library (MVL) - manuals, guides, collections of selected articles

Extending MediaWiki

MediaWiki has been designed to allow for modification without changing the "core code". This makes it easy to update to a new version of MediaWiki without having to manually merge in old extension code changes. There are five main extension points that allow developers to change or extend what MediaWiki can do. The extension points are:

• API – access the data and metadata of MediaWiki instances through a powerful web API.
• Hooks – every time a given event happens do something.
• Parser Functions – create a new command like: {{#if:...|...|...}}
• Skins – change the look and feel of MediaWiki.
• Special Pages – add a new special page.
• Tag Extensions – create a new tag like: <newtag>...</newtag>

Help for extension developers

• Manual:Developing extensions – a guide to developing extensions.
• Extensions FAQ
• Extension Matrix – an auto-generated list of extensions. See also Category:Extensions, a less complete list of extensions.
• Manual:$wgExtensionFunctions – use to defer setup (or run other callbacks) for extensions until after the MediaWiki core is setup.

Help for skin developers

• Manual:Skinning – instructions on how to create a skin for MediaWiki.
• Manual:Skin configuration – a guide to configuring skins for a wiki.