protected function _insertContentNode(Garp_Util_Configuration $contentNodeData) {
        $contentNodeModel = new Model_ContentNode();
        $contentNodeId = $contentNodeModel->insert(array(
            'columns'    => $contentNodeData['columns'],
            'classes'    => $contentNodeData['classes'],
            'type'       => $contentNodeData['type'],
            'chapter_id' => $contentNodeData['chapter_id'],
        ));
        return $contentNodeId;
    }