Parsoid

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Wikimedia Foundation projects Parsoid

A bidirectional runtime wikitext parser. Converts back and forth between wikitext and HTML/XML DOM with RDFa.

Group: Content Transform Team

Start: 2011-10

Team members: Arlo Breault, C.Scott Ananian, Isabelle Hurbain-Palatin, Mateus Santos, Otto Šleger, Subramanya Sastry, Yiannis Giannelos

Backlog: #parsoid

Lead: C.Scott Ananian

Management: Sérgio Lopes

Updates: Parsoid/Releases

Progress: Parsoid/Deployments

A diagram of the Parsoid HTML5 + RDFa wiki runtime For the historic version of Parsoid written in JavaScript (Node.js) until 2020, see Parsoid/JS. Parsoid is a PHP library that is used for converting back and forth between wikitext and HTML. It has been under development since 2012, originally written in JavaScript and built to support the VisualEditor. It has been bundled with MediaWiki since version 1.35. In MediaWiki 1.47, Parsoid is planned to become MediaWiki's default parser, replacing the current native parser, in a project known as parser unification.

Technical details Parsoid is an application which can translate back and forth between MediaWiki's wikitext syntax and an equivalent HTML/RDFa document model with enhanced support for automated processing and rich editing. It has been under development by a team at the Wikimedia Foundation since 2012.

It is currently used extensively by VisualEditor, Content translation and other applications. Parsoid is intended to provide flawless back-and-forth conversion, i.e. to avoid information loss and also prevent "dirty diffs". On Wikimedia wikis, for several applications, Parsoid is currently proxied behind RESTBase, which stores the HTML translated by Parsoid. It is expected that RESTBase will eventually be replaced with a cache more tightly integrated with MediaWiki. For more on the overall project, see this blog post from March 2013. To read about the HTML model being used, see MediaWiki DOM spec. Parsoid was originally structured as a web service and written in JavaScript, making use of Node.js. A tech talk from February 2019 (slides) and blog post describes the process of porting it to PHP. The Parsoid extension API is currently under active development; a tech talk from August 2020 describes this work. GitHub Repository: https://github.com/wikimedia/parsoid

Usage Parsoid/Releases – List of releases made for Parsoid Parsoid/API – for the web API MediaWiki DOM spec – to make sense of the HTML that you get from the API, designed to be useful as a future storage format Parsoid/LanguageConverter – notes on Parsoid's implementation of LanguageConverter Parsoid/Known differences with Core Parser output Installation This extension comes with MediaWiki 1.35 and later, so you do not need to download it. The remaining configuration instructions must still be followed. Parsoid has been included in MediaWiki since version 1.35. No configuration is necessary to enable it. Parsoid exports an internal REST API which was historically used by RESTBase and not accessible outside the WMF internal cluster. This is no longer required for Visual Editor or core read views, and the internal API is being deprecated and is planned for removal in MW 1.43. Parsoid is nominally a composer library used by mediawiki core.

If you still require the internal API for some reason, you can explicitly load Parsoid "as an extension" by adding the following to LocalSettings.php:

wfLoadExtension( 'Parsoid', "$IP/vendor/wikimedia/parsoid/extension.json" );

Any remaining third-party users of the internal Parsoid API are strongly encouraged to migrate to the core REST HTML page endpoint which provides equivalent functionality.

Development Development happens in the Parsoid Git repository. Code review happens in Gerrit. See Gerrit/Getting started to set up an account for yourself. If you use the MediaWiki-Vagrant development environment using a virtual machine, you can simply add the role visualeditor to it and it will set up a working Parsoid along with Extension:VisualEditor. The instructions below are for MediaWiki 1.35 or later. Check Parsoid/JS if you are running the old version of Parsoid written in JavaScript, and used for MW 1.34 and earlier.

Linking a developer checkout of Parsoid In a standard MediaWiki installation, Parsoid is included from MediaWiki as a composer library, wikimedia/parsoid. For development purposes you usually want to use a git checkout of Parsoid, and not the version bundled in MediaWiki core as a composer library. The following lines added to LocalSettings.php allow use of a git checkout of Parsoid (optionally), load the Parsoid REST API with wfLoadExtension (rather than using the version bundled in VisualEditor) and manually do the Parsoid configuration which is usually done by VisualEditor:

$parsoidInstallDir = 'vendor/wikimedia/parsoid'; # bundled copy #$parsoidInstallDir = '/my/path/to/git/checkout/of/Parsoid';

// For developers: ensure Parsoid is executed from $parsoidInstallDir, // (not the version included in mediawiki-core by default) // Must occur *before* wfLoadExtension() if ( $parsoidInstallDir !

== 'vendor/wikimedia/parsoid' ) { function wfInterceptParsoidLoading( $className ) { // Only intercept Parsoid namespace classes if ( preg_match( '/(MW|Wikimedia\\\\)Parsoid\\\\/', $className ) ) { $fileName = Autoloader::find( $className ); if ( $fileName !== null ) { require $fileName; } } } spl_autoload_register( 'wfInterceptParsoidLoading', true, true ); // AutoLoader::registerNamespaces was added in MW 1.39 AutoLoader::registerNamespaces( [ // Keep this in sync with the "autoload" clause in // $parsoidInstallDir/composer.json 'Wikimedia\\Parsoid\\' => "$parsoidInstallDir/src/", ] ); }

wfLoadExtension( 'Parsoid', "$parsoidInstallDir/extension.json" ); unset( $parsoidInstallDir );

These lines are not necessary for most users of VisualEditor, who can use VisualEditor's auto-configuration and the bundled Parsoid code included in MediaWiki, but they will be required for most developers. If you're serving MediaWiki with Nginx, you'll need to also add something like this in your server block (Assuming your MediaWiki setup has its files residing in /w/):

location /w/rest.php/ { try_files $uri $uri/ /w/rest.php?$query_string; }

If you are running Mediawiki using Docker, and linking your local Parsoid repository to Mediawiki, you need to map additional volume to the docker container in docker-compose.override.yml file in media wiki project. To do so, the simplest way is to create docker-compose.override.yml in mediawiki project and put code bellow inside (with path modification). If you already have docker-compose.override.yml file, modify it accordingly.

services: mediawiki: volumes: - ./:/var/www/html/w:cached - /my/path/to/git/checkout/of/Parsoid:/my/path/to/git/checkout/of/Parsoid

To test proper configuration, visit {$wgScriptPath}/rest.php/{$domain}/v3/page/html/Main%20Page where $domain is the hostname in your $wgCanonicalServer. (Note that production WMF servers do not expose the Parsoid REST API to the external network.)

Running the tests To run all parser tests and mocha tests:

$ composer test

The parser tests have quite a few options now which can be listed using php bin/parserTests.php --help. If you have the environment variable MW_INSTALL_DIR pointing to a configured MediaWiki installation, you can run some additional tests with:

$ composer phan-integrated

Converting simple wikitext You can convert simple wikitext snippets from the command line using the parse.php script in the bin/ directory:

$ echo '[[Foo]]' | php bin/parse.php

The parse script has a lot of options. php bin/parse.php --help gives you information about this.

Debugging Parsoid (for developers) See Parsoid/Debugging for debugging tips.

Continuous Integration Parsoid is always available as a library since it is a composer dependency of MediaWiki core. But two pieces are not enabled:

Parsoid ServiceWiring Parsoid's external REST api The test runner Quibble would enable it if it detects mediawiki/services/parsoid.git has been cloned as part of the build. In which case it:

points the autoloader for Wikimedia\Parsoid to the cloned code (effectively replacing the version installed by composer) Load the extension wfLoadExtension( 'Parsoid', '/path/to/cloned/repo' ); The ServiceWiring should be enabled in MediaWiki starting with 1.38. The REST API would theorically never get merged in MediaWiki: a) it has never been exposed to the public in production, it is an internal API used by RESTBase which is going away; b) it never has been security audited and c) it is redundant with the enterprise MediaWiki API.

The solution will be for VisualEditor to invoke Parsoid directly via the VisualEditor Action API which would save a round trip through the REST API. Loading the extension is thus a hack which enables using interfaces subject to change and which we don't really want people to use yet. For most purposes, parsoid should thus not be added as a CI dependency, the only exception as of October 2021 is the Disambiguator MediaWiki extension. Loading parsoid as an extension let us run MediaWiki integration test jobs against mediawiki/services/parsoid.git (such as Quibble, apitesting) and ensure Parsoid and MediaWiki work together. An extension may be able to write tests with Parsoid even when the repository has not been cloned. Since it is a composer dependency of MediaWiki core the MediaWiki\Parsoid namespace is available, but the service wiring part is not (it is extension/src in the Parsoid repository and exposed as the \MWParsoid namespace). The ParsoidTestFileSuite.php code would only run the parser tests if Parsoid has been loaded (which should be the default with MediaWiki 1.38). For CI, Parsoid is tested against the tip of MediaWiki, whereas MediaWiki is tested with the Composer dependency. In case of a breaking change, the Parsoid change get merged first (which breaks its CI but not MediaWiki one) and MediaWiki get adjusted when Parsoid is updated. It is thus a one way change.

Release build For MediaWiki release builds, we have an integration of Parsoid ServiceWiring into VisualEditor in order to have VisualEditor work without further configuration (beside a wfLoadExtension( 'VisualEditor' )). The release build also enables the REST API and hook everything us so that parsoid works out of the box. This is done by copying a bit of Parsoid code into VisualEditor which is not in the master branch of VisualEditor since that would be obsolete as soon as Parsoid is updated. Instead the code is maintained in two places.

Technical documents Parsoid/Internals – documentation about Parsoid internals with links to other details.