(No version information available, might only be in SVN)
Plugins allow for easy extensibility and customization of the framework.
Plugins are classes. The actual class definition will vary based on the component -- you may need to implement this interface, but the fact remains that the plugin is itself a class.
A plugin could be loaded into Yaf by using Yaf_Dispatcher::registerPlugin(), after registerd, All the methods which the plugin implemented according to this interface, will be called at the proper time.
$request
, Yaf_Response_Abstract $response
)