protected void notifyVolumeDelete(String volId) {
   for (VolumeChangeListener listener : vcListeners) listener.volumeDeleted(volId);
 }
 protected void notifyAttributeSet(String volId, String key, String value) {
   for (VolumeChangeListener listener : vcListeners) listener.attributeSet(volId, key, value);
 }
 protected void notifyVolumeChange(VolumeInfo vol) {
   for (VolumeChangeListener listener : vcListeners) listener.volumeChanged(vol);
 }