Exception handling
in EJB.
An APPLICATION EXCEPTION is an exception defined in the throws
clause of a method of the enterprise Bean's home and component interfaces, other
than the java.rmi.RemoteException.
Enterprise bean business methods use APPLICATION exceptions to inform the client
of abnormal application-level conditions, such as unacceptable values of the
input arguments to a business method. A client can typically recover from an
application exception. Application exceptions are not intended for reporting
system-level problems.
For example, the Account enterprise bean may
throw an application exception to report that a debit operation cannot be
performed because of an insufficient balance. The Account
bean should NOT use an application exception to report, for example, the failure
to obtain a database connection.
The javax.ejb.CreateException,
javax.ejb.RemoveException,
javax.ejb.FinderException,
and subclasses thereof are considered to be application exceptions. These exceptions
are used as standard application exceptions to report errors to the client from
the create, remove, and
finder methods.
An application exception class MUST be a subclass (direct or indirect) of
java.lang.Exception. An application exception class MUST NOT be
defined as a subclass of the java.lang.RuntimeException
OR of the java.rmi.RemoteException.
An APPLICATION exception thrown by an enterprise bean instance should be
reported to the client PRECISELY (i.e., the client gets THE SAME exception).
An application exception thrown by an enterprise bean instance should NOT automatically
rollback a client's transaction. The client should typically be given a chance
to recover a transaction from an application exception.
An unexpected exception that may have left the instance's state variables and/or
underlying persistent data in an inconsistent state can be handled safely.
SCJP 5.0 Simulator 642+ Questions With Explanations 