In his latest post, Alexander Netkachev digs a little deeper into the Zend Framework and looks at the Zend_Controller class and its plugin support.

Zend_Controller_Plugin is not covered yet in the documentation but it is a powerful way of extending a controller. Briefly, Zend_Controller_Plugin is used for extending controller functionality by attaching listeners to events, which are fired (or trigged) by the controller classes.

He talks about the plugin interface, how it hooks into the controller and defines the relationship with some pseudo-code (showing implements versus extends). There's talk of the Zend_Controller_Plugin_Broker class and the Zend_Controller_Front. He looks in detail at this last class, showing how it helps to handle incoming requests for the plugin functionality and veen includes working code you demonstrate how.