Basically, these are resource plugins located in library/Zend/Application/Resource/
. You may create also your custom ones.
See My detailed answer to very similar question which should fit also to this one.
Also, see BootstrapAbstract.php
:
/**
* Get class resources (as resource/method pairs)
*
* Uses get_class_methods() by default, reflection on prior to 5.2.6,
* as a bug prevents the usage of get_class_methods() there.
*
* @return array
*/
public function getClassResources()
{
if (null === $this->_classResources) {
if (version_compare(PHP_VERSION, '5.2.6') === -1) {
$class = new ReflectionObject($this);
$classMethods = $class->getMethods();
$methodNames = array();
foreach ($classMethods as $method) {
$methodNames[] = $method->getName();
}
} else {
$methodNames = get_class_methods($this);
}
$this->_classResources = array();
foreach ($methodNames as $method) {
if (5 < strlen($method) && '_init' === substr($method, 0, 5)) {
$this->_classResources[strtolower(substr($method, 5))] = $method;
}
}
}
return $this->_classResources;
}