@Override
 public long getNumberOfChildInstancesOfProcessInstance(final long processInstanceId)
     throws SProcessInstanceReadException {
   try {
     return persistenceRead.selectOne(
         SelectDescriptorBuilder.getNumberOfChildInstancesOfProcessInstance(processInstanceId));
   } catch (final SBonitaReadException e) {
     throw new SProcessInstanceReadException(e);
   }
 }