Callback before object deletation. This will return the 'GUID' of the object instead of whole instance like in annotation.

<?php
function my_component_init(){
		ossn_register_callback('object', 'before:delete', 'my_component_cb');
}
function my_component_cb($callback, $type, $params){
		 $guid = $params['guid'];
		 if($object = ossn_get_object($guid)){
				error_log(print_r($object, true)); 
		 }
}