org.exolab.jms.messagemgr
Class MessageLeaseHelper

java.lang.Object
  |
  +--org.exolab.jms.messagemgr.MessageLeaseHelper

All Implemented Interfaces:

LeaseEventListenerIfc

public class MessageLeaseHelper

extends java.lang.Object

implements LeaseEventListenerIfc

This is a helper class for registering leases for messages with LeaseManager. The lease is based on the JMSExpiration property of the message.
When the lease expires, the listener's onLeaseExpired() method is invoked with a MessageHandle object passed as the argument.
If JMSExpiration is 0, the message never expires.

Version:

$Revision: 1.16 $ $Date: 2003/08/17 01:32:24 $

Author:

Tim Anderson

See Also:

MessageHandle, LeaseManager, LeaseEventListenerIfc

Constructor Summary

MessageLeaseHelper(java.sql.Connection connection, DestinationCache listener)
Construct a helper for the specified destination cache.

MessageLeaseHelper(DestinationCache listener)
Construct a helper for the specified destination cache.

Method Summary

void	addLease(MessageHandle handle) Add a lease for the handle to notify listener when message expires.
void	addLease(MessageImpl message) Add a lease for message to notify listener when message expires.
void	clear() Clears all leases
protected void	init(DestinationCache listener, java.sql.Connection connection) This method is used for all common initialization code.
void	onLeaseExpired(java.lang.Object handle) Invoked when a lease has expired.
void	removeLease(MessageImpl message) Remove a lease for a message

Methods inherited from class java.lang.Object

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

Constructor Detail

MessageLeaseHelper

public MessageLeaseHelper(DestinationCache listener)
                   throws PersistenceException

Construct a helper for the specified destination cache.

Parameters:

listener - the object to notify when a lease expires

Throws:

PersistenceException - if the destination is administered and the set of non-expired messages cannot be determined

MessageLeaseHelper

public MessageLeaseHelper(java.sql.Connection connection,
                          DestinationCache listener)
                   throws PersistenceException

Construct a helper for the specified destination cache.

This method is only called during cache init time and is used to retrieve persistent messages with leases.

Parameters:

connection - the connection to use to retrieve persistent messages with leases

listener - the object to notify when a lease expires

Throws:

PersistenceException - if the destination is administered and the set of non-expired messages cannot be determined

Method Detail

addLease

public void addLease(MessageImpl message)

Add a lease for message to notify listener when message expires. The lease uses JMSExpiration property of the message. If this is unset or 0, then no lease is registered. If non-zero, a MessageHandle object is registered with LeaseManager, and the listener will be notified with this object when the lease expires.

Parameters:

message - the message to add a lease for

addLease

public void addLease(MessageHandle handle)

Add a lease for the handle to notify listener when message expires. The lease uses JMSExpiration property of the message. If this is unset or 0, then no lease is registered. If non-zero, a MessageHandle object is registered with LeaseManager, and the listener will be notified with this object when the lease expires.

Parameters:

handle - message handle to add

removeLease

public void removeLease(MessageImpl message)

Remove a lease for a message

Parameters:

message - the message to remove the lease for

clear

public void clear()

Clears all leases

onLeaseExpired

public void onLeaseExpired(java.lang.Object handle)

Invoked when a lease has expired.
It removes the local lease, and notifies the listener.

Specified by:

onLeaseExpired in interface LeaseEventListenerIfc

Parameters:

handle - An instance of MessageHandle

init

protected void init(DestinationCache listener,
                    java.sql.Connection connection)
             throws PersistenceException

This method is used for all common initialization code. It basically retrieves all non-expired messages and places them in the memory

Parameters:

listener - the cache listening for expired leases.

connection - the persistent connection to use

Throws:

PersistenceException - if the destination is administered and the set of non-expired messages cannot be determined