EventBus

EventBus is a MediaWiki extension that produces changes to a RESTful event service.

This extension is part of a larger effort to create a general purpose event system, to reliably propagate state changes from one part of the infrastructure, to another. Since this approach relies upon hooks, it is not atomic (delivery of an event could fail after MediaWiki has committed the corresponding change), and so does not provide the reliability we're aiming for. Therefore, this extension should be considered an interim solution, until the requisite changes can be made to MediaWiki core.

Configuration

EventBus supports configuration of multiple event service endpoints via the EventServices main config array. It expects entries keyed by event service name pointing at arrays of event service config. E.g.

$wgEventServices = [
    'eventbus-main' => [
        'url' => 'http://locahost:8085/v1/topics',
        'timeout' => 5,
    ],
    'eventgate-main' => [
        'url' => 'http://localhost:8192/v1/topics',
    ],
];

EventBus instances should be created via the static getInstance method. This method takes one of the configured event service names from the EventServices main config.

EnableEventBus config parameter specifies which types of events the extension will produce. Possible options are TYPE_NONE, TYPE_EVENT, TYPE_JOB, TYPE_PURGE or TYPE_ALL. Specifying multiple types using | as a delimiter is supported. Example: TYPE_JOB|TYPE_PURGE

EventBus also supports per stream event service configuration, meaning you can configure specifically which event service should be used for a particular stream name. This is handled via the EventStreamConfig extension. See docs there on how to configure $wgEventStreams. To use $wgEventStreams to specify an event service, add the 'destination_event_service' setting to your stream's config entry. E.g.

$wgEventStreams = [
    [
        'stream' => 'mediawiki.my-event',
        'destination_event_service' => 'eventgate-main'
    ]
];

Per stream configuration via EventStreamConfig is optional. The default behavior is to produce all streams to the service specified by $wgEventServiceDefault. You must set $wgEventServiceDefault to the an entry in $wgEventServices to be used in case a stream's destination_event_service setting is not provided.

$wgEventServiceDefault = 'eventgate-main';

EventBus RCFeed

This extension also provides an FormattedRCFeed and RCFeedFormatter implementation That will allow RCFeed configuration to post to the EventBus service in the mediawiki.recentchange topic. To use, add the following to your LocalSettings.php:

use MediaWiki\Extension\EventBus\Adapters\RCFeed\EventBusRCFeedEngine;
use MediaWiki\Extension\EventBus\Adapters\RCFeed\EventBusRCFeedFormatter;

$wgRCFeeds['eventgate-main'] = array(
    'class'            => EventBusRCFeedEngine::class,
    'formatter'        => EventBusRCFeedFormatter::class,
    // This should be the name of an event service entry
    // defined in $wgEventServices.
    'eventServiceName' => 'eventgate-main',
);

References

• Reliable publish / subscribe event bus
• Integrate event production into MediaWiki

License

EventBus is licensed under the GNU General Public License 2.0 or any later version. You may obtain a copy of this license at http://www.gnu.org/copyleft/gpl.html.