storage stuff

gistfile1.php

class DatabaseStorageController implements EntityStorageControllerInterface, ExtensibleStorageInterface {

   protected $class = 'ExtensibleDBStorageHelper';

   protected function getExtensibleStorageHelper() {
      ...
   }


   function save() {
     // save base fields.
     $this->getExtensibleStorageHelper()->write(...);
   }

}

class MongoStorageController implements EntityStorageControllerInterface, ExtensibleStorageInterface {


   function save() {
     // Store the document in mongo.
   }

}