MediaWiki Introduction 2023

MediaWiki Introduction 2023 is a 3-part video series by Timo Tijhof, recorded in December 2023 for the MediaWiki Code Jam.

Part 1: MediaWiki core concepts

Watch on Wikimedia Commons. • Watch on YouTube

Timestamps:

00:00 Outline
00:50 Database schema
01:37 Users
02:55 Preferences
04:12 Localisation
05:02 Permissions
08:50 Bot passwords
10:10 Logging
11:58 Comments
12:35 Recent changes
15:39 Pages
16:00 Namespaces
18:14 Revisions
18:20 Example: Save an edit
19:59 Example: View a page
20:52 Link tables
21:02 Categories
24:20 Templates
25:05 Image links
25:59 GLAM
26:43 External links
27:40 Statistics
28:02 Search
29:14 JobQueue
31:58 Multimedia

High-level product and architecture perspective. Component walk-through.

• Database layout
• Who writes Wikipedia
• Why create an account
• CSSJanus docs
• CSSJanus demo
• Permissions
• Change user rights
• Bot passwords
• Logging
• No original research
• Recent changes
• RCFeed
• Listen to Wikipedia
• CodePen
• ClueBot
• Namespaces
• Special pages
• Page table
• Revision table
• Text table
• External storage
• Example category
• Everything is a wiki page
• GLAM
• Glamorous tool
• Example photo
• Statistics
• JobQueue
• MediaWiki Engineering - Performance practices
• Multimedia

Part 2: Wikipedia's extensions

Watch on Wikimedia Commons. • Watch on YouTube

Timestamps:

00:00 Outline
00:25 What is an extension?
01:52 How to install an extension?
02:01 Install WikiEditor
02:54 Install VisualEditor
03:58 Wikipedia's extensions
04:10 CentralAuth
04:38 Echo
04:56 OAuth for MediaWiki
05:40 Editor extensions
05:48 Parser extensions
06:37 Cite extension
07:37 EasyTimeline
07:56 InputBox extension
08:38 Scribunto
09:38 Faster editing performance
11:24 Media handlers
11:31 TimedMediaHandler
11:42 3D extension for MediaWiki
11:57 Spam prevention extensions
12:35 Gadgets
13:05 Gadget demo
13:41 Gadget examples

What is an extension?

How to install an extension in two easy steps.

Walk-through the installed extensions via Wikipedia's Special:Version page.

• What is an extension
• WikiEditor extension
• VisualEditor extension
• Wikipedia's extensions
• CentralAuth
• Echo
• Cite
• EasyTimeline
• EasyTimeline example: Version lifecycle
• InputBox
• InputBox example: Incident status
• Scribunto
• Lua example: SchemaDiagram
• What Lua scripting means for Wikimedia (2013)
• How we made editing Wikipedia twice as fast (2014)
• Save Timing in Grafana
• TimedMediaHandler
• 3D extension
• AbuseFilter
• Gadgets
• Gadget example: RTRC
• Gadget example: Stockphoto
• Half-timbered mansion, by Radomianin

Part 3: Write an example patch

• Homework preparation:
  • Quickstart.
  • Run PHPUnit, e.g. composer phpunit -- tests/phpunit/includes/ResourceLoader/
  • Run QUnit, e.g. view http://localhost:4000/index.php/Special:JavaScriptTest
  • Clone the "examples" repo in your extensions/ directory, and enable it.
• How does an extension actually work?
  • Manual:Extension registration (wfLoadExtension loads extension.json)
  • Manual:Extension.json/Schema ("type", "SpecialPages" is a registry, "AutoloadNamespaces" is a registry).
  • Best practices for extensions (keep it simple, reduce decisions/choices, fewer things to verify, "includes/").
  • Manual:Coding conventions/PHP (quick open, file name = class name)
• How do special pages work?
  • MediaWiki takes care of URL routing.
  • File:MediaWiki_infrastructure_2022.png
  • MediaWiki at WMF
  • MediaWiki loves registries that do things for you automatically. MediaWiki constructs your SpecialPage class, and skins the output.
  • Special:SpecialPages.
  • Special:HelloWorld -> execute, now it's our turn.
  • OutputPage
  • RequestContext->msg
• Localisation
  • uselang=qqx (debugging, contributions, Translatewiki.net)
  • Help:System message
  • i18n/en.json (git-grep, "MessageDirs")
• Excercise 1: Edit a localisation message. Change the "example-helloworld" message and notice the change on Special:HelloWorld.
• Excercise 2: Create a new localisation message, and output it on Special:HelloWorld.
• Hooks
  • extension.json ("Hooks" is a registry, "HookHandlers" is a registry)
  • MediaWiki will call Hooks.php#onSomething, now it's our turn.
  • Manual:Hooks
  • BeforePageDisplay
  • $wgExampleEnableWelcome (extension.json, "config" is another registry)
  • Namespaces (remember from Part 1)
• Excercise 3: Make a config change. Edit LocalSettings.php to disable $wgExampleEnableWelcome and notice the change on Main_Page. Comment your edit to re-enable it.
• Excercise 4: Edit a hook handler. Make it welcome you on special pages instead of articles. Notice the change on Special:HelloWorld and Main Page.
• ResourceLoader
  • extension.json ("ResourceModules" is another registry, "dependencies", "packageFiles")
  • ResourceLoader/Developing with ResourceLoader
  • onBeforePageDisplay, OutputPage::addModule.
  • welcome.js
  • styles.css
  • Special:JavaScriptTest?filter=welcome
  • ext.Example.welcome.test.js
• Excercise 5: Fix a bug and test it with QUnit. The welcome message greets you with the wrong day.
• Save your change and upload it to Gerrit:
  • git add -p
  • git commit
  • git-review.
  • Gerrit.
  • WMF CI: Jenkins build output.