org.exolab.jms.messagemgr
Class TopicDestinationCache

java.lang.Object
  |
  +--org.exolab.jms.messagemgr.DestinationCache
        |
        +--org.exolab.jms.messagemgr.TopicDestinationCache

All Implemented Interfaces:

GarbageCollectable, Identifiable, LeaseEventListenerIfc, MessageManagerEventListener, java.io.Serializable

public class TopicDestinationCache

extends DestinationCache

A DestinationCache for Topics. This cache extends DestinationCache but does not actually hold a reference to the messages. Instead it forwards them on to registered consumers.

We may need to build the cache for clients that fail over to the new server so we should maintain a cache of at least persistent messages handles. This is something that needs to be considered. As for non-persistent messages well that is the penalty for using them. If you want to ensure that you get every message, even during failover then you best publsih them using persistent delivery mode.

Version:

$Revision: 1.22 $ $Date: 2003/10/21 14:41:24 $

Author:

Jim Alateras

See Also:

Serialized Form

Fields inherited from class org.exolab.jms.messagemgr.DestinationCache

_consumers, _leaseHelper

Method Summary

boolean	canDestroy() Determines if this cache can be destroyed.
JmsDestination	getDestination() Return a reference to the underlying destination
int	getMessageCount() Return the number of messages currently active for this destination
int	hashCode()
boolean	messageAdded(JmsDestination destination, MessageImpl message) This method is called when the MessageMgr adds a message for this destination to the cache
void	messageRemoved(JmsDestination destination, MessageImpl message) This method is called when the MessageMgr removes a message from the cache.
boolean	persistentMessageAdded(java.sql.Connection connection, JmsDestination destination, MessageImpl message) This event is called when the MessageMgr adds a persistent message to the cache.
void	persistentMessageRemoved(java.sql.Connection connection, JmsDestination destination, MessageImpl message) This event is called when the MessageMgr removes a persistent message from the cache.
boolean	registerConsumer(ConsumerEndpoint consumer) Register a consumer with this cache.
protected MessageImpl	resolveExpiredMessage(MessageHandle handle) Resolve an expired message through its handle
java.lang.String	toString()

Methods inherited from class org.exolab.jms.messagemgr.DestinationCache

collectGarbage, getConsumers, getDestinationByName, getId, getMaximumSize, onLeaseExpired, setCacheEvictionPolicy, setMaximumSize, shutdown, unregisterConsumer

Methods inherited from class java.lang.Object

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

Method Detail

getDestination

public JmsDestination getDestination()

Description copied from class: DestinationCache

Return a reference to the underlying destination

Overrides:

getDestination in class DestinationCache

Following copied from class: org.exolab.jms.messagemgr.DestinationCache

Returns:

JmsDestination

messageAdded

public boolean messageAdded(JmsDestination destination,
                            MessageImpl message)

Description copied from class: DestinationCache

This method is called when the MessageMgr adds a message for this destination to the cache

Overrides:

messageAdded in class DestinationCache

Following copied from class: org.exolab.jms.messagemgr.DestinationCache

Parameters:

message - - message added to cache

messageRemoved

public void messageRemoved(JmsDestination destination,
                           MessageImpl message)

Description copied from class: DestinationCache

This method is called when the MessageMgr removes a message from the cache.

Overrides:

messageRemoved in class DestinationCache

Following copied from class: org.exolab.jms.messagemgr.DestinationCache

Parameters:

message - - message removed from cache

persistentMessageAdded

public boolean persistentMessageAdded(java.sql.Connection connection,
                                      JmsDestination destination,
                                      MessageImpl message)
                               throws PersistenceException

Description copied from interface: MessageManagerEventListener

This event is called when the MessageMgr adds a persistent message to the cache.

Following copied from interface: org.exolab.jms.messagemgr.MessageManagerEventListener

Parameters:

connection - the database connection

destination - the message's destination

message - message added to cache

Returns:

trueThrows:

PersistenceException - if there is a persistence related problem

persistentMessageRemoved

public void persistentMessageRemoved(java.sql.Connection connection,
                                     JmsDestination destination,
                                     MessageImpl message)
                              throws PersistenceException

Description copied from interface: MessageManagerEventListener

This event is called when the MessageMgr removes a persistent message from the cache.

Following copied from interface: org.exolab.jms.messagemgr.MessageManagerEventListener

Parameters:

connection - the database connection

message - message to remove from cache

destination - the message's destination

Throws:

PersistenceException - - if there is a persistence related problem

registerConsumer

public boolean registerConsumer(ConsumerEndpoint consumer)

Description copied from class: DestinationCache

Register a consumer with this cache. Part of the registration process will be to seed the ConsumerEndpoint with an initial list of messages that it needs to consume and then feed messages to it through the specified listener object.

Messages are subsequently passed down to the consumer's through the listener, as they enter the DestinationCache.

Overrides:

registerConsumer in class DestinationCache

Following copied from class: org.exolab.jms.messagemgr.DestinationCache

Parameters:

consumer - - message consumer for this destination

Returns:

boolean - true if registered and false otherwise

getMessageCount

public int getMessageCount()

Description copied from class: DestinationCache

Return the number of messages currently active for this destination

Overrides:

getMessageCount in class DestinationCache

Following copied from class: org.exolab.jms.messagemgr.DestinationCache

Returns:

int - number of active messages

canDestroy

public boolean canDestroy()

Determines if this cache can be destroyed. A TopicDestinationCache can be destroyed if there are no active consumers.

Overrides:

canDestroy in class DestinationCache

Returns:

true if the cache can be destroyed, otherwise false

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

resolveExpiredMessage

protected MessageImpl resolveExpiredMessage(MessageHandle handle)

Resolve an expired message through its handle

Overrides:

resolveExpiredMessage in class DestinationCache

Parameters:

handle - the expired message's handle

Returns:

the expired message. May be null.