/**
  * @param edge
  * @param target
  * @param validate
  * @throws Exception
  */
 public void fireTargetChanged(Object edge, Object target, boolean validate) throws Exception {
   if (backend != null) backend.targetChanged(this, edge, target, validate);
 }
 /**
  * @param cell
  * @param change
  * @param validate
  * @throws Exception
  */
 public void fireAttributesChanged(Object cell, Map change, boolean validate) throws Exception {
   if (backend != null) backend.attributesChanged(this, cell, change, validate);
 }
 /**
  * @param child
  * @param parent
  * @param validate
  * @throws Exception
  */
 public void fireParentChanged(Object child, Object parent, boolean validate) throws Exception {
   if (backend != null) backend.parentChanged(this, child, parent, validate);
 }
 /**
  * @param edge
  * @param source
  * @param validate
  * @throws Exception
  */
 public void fireSourceChanged(Object edge, Object source, boolean validate) throws Exception {
   if (backend != null) backend.sourceChanged(this, edge, source, validate);
 }
 /**
  * @param object
  * @param validate
  * @throws Exception
  */
 public void fireCellRemoved(Object object, boolean validate) throws Exception {
   if (backend != null) backend.cellRemoved(this, object, validate);
 }
 /**
  * @param edge
  * @param source
  * @param target
  * @param validate
  * @throws Exception
  */
 public void fireEdgeAdded(Object edge, Object source, Object target, boolean validate)
     throws Exception {
   if (backend != null) backend.edgeAdded(this, edge, source, target, validate);
 }
 /**
  * @param vertex
  * @param validate
  * @throws Exception
  */
 public void fireVertexAdded(Object vertex, boolean validate) throws Exception {
   if (backend != null) backend.vertexAdded(this, vertex, validate);
 }
 /** @throws Exception */
 public void fireRollback() throws Exception {
   if (backend != null) backend.rollback();
 }
 /** @throws Exception */
 public void fireCommit() throws Exception {
   if (backend != null) backend.commit();
 }