ejava.examples.txhotel.ejb

Class HotelReservationSessionEJB

java.lang.Object

ejava.examples.txhotel.ejb.HotelReservationSessionEJB

All Implemented Interfaces:

HotelReservationSession, HotelReservationSessionLocal, HotelReservationSessionRemote, SessionSynchronization

public class HotelReservationSessionEJB
extends Object
implements HotelReservationSessionLocal, HotelReservationSessionRemote, SessionSynchronization

This class provides an example of a stateful session bean wrapper around stateless server calls. In this example case, the user wishes to make several reservations. However, the stateless session bean will commit them to the database one at a time. This wrapper shows how someone could temporarily store them on the server while the entire set is being sanity checked. Once they are good to go, a single transaction is started by the commit() method to invoke the stateless session bean for each transaction. We can easily find tons of fault and areas for improvement with the actual business logic. However, the basic concept is that the stateful session bean can perform some of the actions of the stateless session bean outside of a transaction and then commit the changes as one unit when ready. The instance is thrown away no matter what happens. We could just as easily keep it around and add some edit functions to fix the erroneous information that caused the rollback.

This bean is deployed 3 times; default configuration, using a transaction Required stateless session bean, and using a tranaction RequiresNew stateless session bean. The test client will try all 3. You'll notice that the one with RequiresNew, will not be able to rollback successful reservations because it operates in a separate transaction. The one with tranaction Required allows all to be rolled back because it joins this tranaction.

This bean is also configured quite a bit from the ejb-jar.xml file; using less annotations then the other stateless session bean example.

It implements the javax.ejb.SessionSynchronization interface so that it can listen, impact, or react to the state of the active transaction.

Author:

jcstaff

Field Summary

Fields

Modifier and Type	Field and Description
private SessionContext	ctx
private HotelReservationSession	impl
private static org.apache.commons.logging.Log	log
private HotelRegistrationLocal	reservationist

Constructor Summary

Constructors

Constructor and Description
HotelReservationSessionEJB()

Method Summary

Modifier and Type	Method and Description
void	afterBegin() This is called to tell us the transaction has started because we implement SessionSynchronization interface.
void	afterCompletion(boolean status) This is called to tell us how the transaction did.
void	beforeCompletion() This is called to give us a chance to complain before the transaction really commits.
void	cancelReservations()
void	close() This method will destroy the stateful instance.
void	closing() This method is called just prior to the bean being destroyed.
List<Reservation>	commit()
void	createReservation(Person person, Date startDate, Date endDate)
void	init() This method is called when the bean is instantiated to perform manual initialization.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

private static final org.apache.commons.logging.Log log

impl

private HotelReservationSession impl

ctx

private SessionContext ctx

reservationist

private HotelRegistrationLocal reservationist

Constructor Detail

HotelReservationSessionEJB

public HotelReservationSessionEJB()

Method Detail

init

@PostConstruct
public void init()

This method is called when the bean is instantiated to perform manual initialization. It creates the business logic implementation class, instantiates and assigns a DAO, and assigns the EntityManager from the DAO(s) to use. This should map the the ejb-jar.xml post-construct element.

closing

@PreDestroy
public void closing()

This method is called just prior to the bean being destroyed. This should map to the ejb-jar.xml pre-destroy element.

close

public void close()

This method will destroy the stateful instance.

Specified by:

close in interface HotelReservationSession

createReservation

public void createReservation(Person person,
                              Date startDate,
                              Date endDate)
                       throws HotelReservationException

Specified by:

createReservation in interface HotelReservationSession

Throws:

HotelReservationException

cancelReservations

public void cancelReservations()
                        throws HotelReservationException

Specified by:

cancelReservations in interface HotelReservationSession

Throws:

HotelReservationException

commit

public List<Reservation> commit()
                         throws HotelReservationException

Specified by:

commit in interface HotelReservationSession

Throws:

HotelReservationException

afterBegin

public void afterBegin()

This is called to tell us the transaction has started because we implement SessionSynchronization interface.

Specified by:

afterBegin in interface SessionSynchronization

beforeCompletion

public void beforeCompletion()
                      throws EJBException,
                             RemoteException

This is called to give us a chance to complain before the transaction really commits.

Specified by:

beforeCompletion in interface SessionSynchronization

Throws:

EJBException

RemoteException

afterCompletion

public void afterCompletion(boolean status)

This is called to tell us how the transaction did.

Specified by:

afterCompletion in interface SessionSynchronization