protected function getExtensionManager()
    {
        if ($this->getServiceLocator()->has(common_ext_ExtensionsManager::SERVICE_ID)) {
            $service = $this->getServiceLocator()->get(common_ext_ExtensionsManager::SERVICE_ID);
        } else {
            $service = new common_ext_ExtensionsManager();
            $this->getServiceLocator()->propagate($service);
        }
        return $service;
    }