public function getUsers( core_kernel_classes_Resource $role)
    {
        $returnValue = array();

        $filters = array(GenerisRdf::PROPERTY_USER_ROLES => $role->getUri());
        $options = array('like' => false, 'recursive' => true);

        $userClass = new core_kernel_classes_Class(GenerisRdf::CLASS_GENERIS_USER);
        $results = $userClass->searchInstances($filters, $options);

        $returnValue = array_keys($results);

        return (array) $returnValue;
    }