Editing API:EPrints/Plugin/Event (section)

==DESCRIPTION==
Event plugins are called by the indexer to actually do work. [[API:EPrints/DataObj/EventQueue|EPrints::DataObj::EventQueue]] objects are stored in the database and executed once their start_time is due. The object contains the plugin ID, action and optionally parameters.

Action is the sub called on the plugin. This sub must return undef or a valid response constant recognised by [[API:EPrints/DataObj/EventQueue#execute|EPrints::DataObj::EventQueue/execute]].

Parameters can contain any Perl data structure that can be serialised by {{API:PodLink|file=Storable|package_name=Storable|section=|text=Storable}}. As a special case parameters that look like an internal id are re-instantiated as the referenced object before the plugin action is called.

Events also support scheduled (or repeating) events by calling [[API:EPrints/Plugin/Event#cron|cron]] on this class with the actual plugin id/action/parameters to call. The scheduled event isn't called directly but is triggered via a new event object with a start_time of now.

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