Exception Flow from DAO -> EJB
==============================

- NamingEx thrown up as InventoryDAOSysException
- SQL exceptions thrownup as InventoryDAOSysException
- user errors (empty field et al) passed up as InventoryDAOAppException
- errors while database update caused by user error passed up as InventoryDAODBUpdateException
- Absence of a row with given primary key passed up as InventoryDAOFinderException


Exception Flow from EJB up
==========================

- InventoryDAOSysExceptions thrown up as EJBException
- InventoryDAOFinderEx thrown up as FinderEx
- InventoryDAODBUpdate thrown up as RemoveEx / as the case may be (depending
  in calling context)
- ejbLoad and ejbStore methods convert App exceptions from DAO into EJBException because these methods cannot have any other signature