ejava.examples.txagent.ejb

Class AgentReservationSessionEJB

java.lang.Object

ejava.examples.txagent.ejb.AgentReservationSessionEJB

All Implemented Interfaces:

AgentReservationSession, AgentReservationSessionLocal, AgentReservationSessionRemote, SessionSynchronization

public class AgentReservationSessionEJB
extends Object
implements AgentReservationSessionLocal, AgentReservationSessionRemote, SessionSynchronization

This class provides an example of a Stateful session bean that will try to coordinate its local transaction with the tranaction of a remote session bean. The actual configuration may not really proove anything since the two applications will probably be deployed to the same server. We would need to break them apart into separate servers and separate server implementations to show anything really significant.

Note too that this session bean declares its transaction properties using class annotations. By default, this stateful session bean runs without a tranaction while caching reservations for the user. A transaction is required only for the commit() call, which also signals the removal of this bean instance.

The bean also implements the javax.ejb.SessionSynchronization interface. This allows it to be called at the start and end of a transaction so that it has a chance to update its cached values appropriately. This bean, however, just prints some debug.

Author:

jcstaff

Field Summary

Fields

Modifier and Type	Field and Description
private AgentReservationSession	agentSession
private SessionContext	ctx
private EntityManager	em
private static org.apache.commons.logging.Log	log
private HotelReservationSessionRemote	reservationSession

Constructor Summary

Constructors

Constructor and Description
AgentReservationSessionEJB()

Method Summary

Modifier and Type	Method and Description
void	addReservation(Person person, Date startDate, Date endDate)
void	afterBegin() This method is called at the beginning of a transaction because of the implements SessionSynchronization interface.
void	afterCompletion(boolean status) This method is called just after the transaction has committed to tell us what happened.
void	beforeCompletion() This method is called just before the transaction has committed to give the bean a chance to complain.
void	cancelBooking()
void	close()
void	closing() This method should be called when the bean is destroyed because of the @PreDestory annotation.
Booking	commit() This method implements the big-bang.
void	createBooking()
void	init() This method is called immediately after dependency injection and before any business method because of the @PostConstruct annotation.

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

ctx

private SessionContext ctx

em

private EntityManager em

reservationSession

private HotelReservationSessionRemote reservationSession

agentSession

private AgentReservationSession agentSession

Constructor Detail

AgentReservationSessionEJB

public AgentReservationSessionEJB()

Method Detail

init

@PostConstruct
public void init()

This method is called immediately after dependency injection and before any business method because of the @PostConstruct annotation. It provides a chance to do any manual construction of the overall bean. In this case, we need to instantiate out business logic implementation, provide it a DAO, and register the EntityManager for the DAO(s) to use.

closing

@PreDestroy
public void closing()

This method should be called when the bean is destroyed because of the @PreDestory annotation.

createBooking

public void createBooking()
                   throws AgentReservationException

Specified by:

createBooking in interface AgentReservationSession

Throws:

AgentReservationException

addReservation

public void addReservation(Person person,
                           Date startDate,
                           Date endDate)
                    throws AgentReservationException

Specified by:

addReservation in interface AgentReservationSession

Throws:

AgentReservationException

cancelBooking

public void cancelBooking()
                   throws AgentReservationException

Specified by:

cancelBooking in interface AgentReservationSession

Throws:

AgentReservationException

commit

public Booking commit()
               throws AgentReservationException

This method implements the big-bang. All information, up to this point is being cached in the business logic instance and remote hotel reservation session; all owned by this specific instance. This method causes a transaction to be started, the remote reservations to be commited by the hotel, and the booking to be stored locally with references to the reservations. If it all works; all should be stored. If something fails (e.g., an invalid reservation date), then nothing will be saved.

Specified by:

commit in interface AgentReservationSession

Throws:

AgentReservationException

close

public void close()

Specified by:

close in interface AgentReservationSession

afterBegin

public void afterBegin()

This method is called at the beginning of a transaction because of the implements SessionSynchronization interface.

Specified by:

afterBegin in interface SessionSynchronization

beforeCompletion

public void beforeCompletion()
                      throws EJBException,
                             RemoteException

This method is called just before the transaction has committed to give the bean a chance to complain.

Specified by:

beforeCompletion in interface SessionSynchronization

Throws:

EJBException

RemoteException

afterCompletion

public void afterCompletion(boolean status)

This method is called just after the transaction has committed to tell us what happened.

Specified by:

afterCompletion in interface SessionSynchronization