Zend Framework - EventManager component

 The `Zend\EventManager` is a component designed for the following use cases:
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  * Implementing simple subject/observer patterns.
  * Implementing Aspect-Oriented designs.
  * Implementing event-driven architectures.
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 The basic architecture allows you to attach and detach listeners to named
 events, both on a per-instance basis as well as via shared collections;
 trigger events; and interrupt execution of listeners.
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 Zend is a PHP framework for developing web applications and services.