org.jboss.messaging.core
Class ChannelSupport

java.lang.Object
  org.jboss.messaging.core.ChannelSupport

All Implemented Interfaces:

Channel, DeliveryObserver, Distributor, Receiver

Direct Known Subclasses:

Pipe, Queue

public abstract class ChannelSupport

extends java.lang.Object

implements Channel

A basic channel implementation. It supports atomicity, isolation and, if a non-null PersistenceManager is available, it supports recoverability of reliable messages.

Version:

$Revision: 1.65 $ $Id: ChannelSupport.java,v 1.65 2006/06/27 19:44:39 timfox Exp $

Author:

Ovidiu Feodorov, Tim Fox

Field Summary

protected long	channelID
protected MemoryManager	mm
protected MessageStore	ms
protected PersistenceManager	pm
protected Router	router
protected State	state

Constructor Summary

protected

ChannelSupport(long channelID, MessageStore ms, PersistenceManager pm, MemoryManager mm, boolean acceptReliableMessages, boolean recoverable, int fullSize, int pageSize, int downCacheSize)

Method Summary

boolean	acceptReliableMessages() A non-recoverable channel cannot guarantee recoverability for reliable messages so by default it won't accept reliable messages.
void	acknowledge(Delivery d, Transaction tx)
boolean	add(Receiver r) Add a local receiver to this distributor.
java.util.List	browse()
java.util.List	browse(Filter f)
void	cancel(Delivery d)
void	clear() Remove all receivers.
void	close()
boolean	contains(Receiver r)
boolean	deliver()
protected boolean	deliver(DeliveryObserver sender, Receiver receiver) Delivery for the channel must be synchronized.
boolean	deliver(Receiver r) Synchronously pushes the "oldest" message stored by the channel to the receiver.
long	getChannelID()
MessageStore	getMessageStore()
Delivery	handle(DeliveryObserver sender, Routable r, Transaction tx) A receiver can return an active, "done" or null delivery.
boolean	isRecoverable()
java.util.Iterator	iterator()
protected MessageReference	obtainReference(Routable r)
protected void	processMessageBeforeStorage(MessageReference reference) Give subclass a chance to process the message before storing it internally.
boolean	remove(Receiver r) Remove a local receiver from this distributor.
void	removeAllMessages()

Methods inherited from class java.lang.Object

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

Field Detail

channelID

protected long channelID

router

protected Router router

state

protected State state

ms

protected MessageStore ms

pm

protected PersistenceManager pm

mm

protected MemoryManager mm

Constructor Detail

ChannelSupport

protected ChannelSupport(long channelID,
                         MessageStore ms,
                         PersistenceManager pm,
                         MemoryManager mm,
                         boolean acceptReliableMessages,
                         boolean recoverable,
                         int fullSize,
                         int pageSize,
                         int downCacheSize)

Parameters:

acceptReliableMessages - - it only makes sense if tl is null. Otherwise ignored (a recoverable channel always accepts reliable messages)

Method Detail

handle

public Delivery handle(DeliveryObserver sender,
                       Routable r,
                       Transaction tx)

Description copied from interface: Receiver

A receiver can return an active, "done" or null delivery. The method returns null in case the receiver doesn't accept the message. The return value is unspecified when the message is submitted in the context of a transaction (tx not null).

Specified by:

handle in interface Receiver

Parameters:

sender - - the component the delivery should be acknowledged to.

See Also:

Delivery, DeliveryObserver

acknowledge

public void acknowledge(Delivery d,
                        Transaction tx)

Specified by:

acknowledge in interface DeliveryObserver

cancel

public void cancel(Delivery d)
            throws java.lang.Throwable

Specified by:

cancel in interface DeliveryObserver

Throws:

java.lang.Throwable

add

public boolean add(Receiver r)

Description copied from interface: Distributor

Add a local receiver to this distributor.

Specified by:

add in interface Distributor

Returns:

true if the distributor did not already contain the specified receiver and the receiver was added to the distributor, false otherwise.

remove

public boolean remove(Receiver r)

Description copied from interface: Distributor

Remove a local receiver from this distributor.

Specified by:

remove in interface Distributor

Returns:

true if this distributor contained the specified receiver.

clear

public void clear()

Description copied from interface: Distributor

Remove all receivers.

Specified by:

clear in interface Distributor

contains

public boolean contains(Receiver r)

Specified by:

contains in interface Distributor

iterator

public java.util.Iterator iterator()

Specified by:

iterator in interface Distributor

Returns:

an iterator of local receivers

getChannelID

public long getChannelID()

Specified by:

getChannelID in interface Channel

isRecoverable

public boolean isRecoverable()

Specified by:

isRecoverable in interface Channel

Returns:

true if the channel can guarantee recoverability for reliable messages. Recoverability is not guaranteed for non-reliable messages (and should not be provided by default, for performance reasons), even if the channel is recoverable.

acceptReliableMessages

public boolean acceptReliableMessages()

Description copied from interface: Channel

A non-recoverable channel cannot guarantee recoverability for reliable messages so by default it won't accept reliable messages. However, there are situations when discarding a reliable message is acceptable for a specific instance of a channel, so it should be a way to configure the channel to do so. A channel indicates unequivocally whether it accepts reliable messages or not returning true or false as result of this method. A recoverable channel must always accept reliable messages, so this method must always return true for a recoverable channel.

Specified by:

acceptReliableMessages in interface Channel

Returns:

false if the channel doesn't accept reliable messages.

See Also:

State.acceptReliableMessages()

browse

public java.util.List browse()

Specified by:

browse in interface Channel

Returns:

a List containing messages being held by the channel. The list includes messages in process of being delivered and messages for which delivery hasn't been attempted yet.

browse

public java.util.List browse(Filter f)

Specified by:

browse in interface Channel

See Also:

Channel.browse()

getMessageStore

public MessageStore getMessageStore()

Specified by:

getMessageStore in interface Channel

deliver

public boolean deliver()

Specified by:

deliver in interface Channel

deliver

public boolean deliver(Receiver r)

Description copied from interface: Channel

Synchronously pushes the "oldest" message stored by the channel to the receiver. If receiver is null, it delivers the message to the first available receiver.

Specified by:

deliver in interface Channel

Returns:

true if a message was handed over to the receiver and the channel got a delivery in exchange, or false otherwise.

close

public void close()

Specified by:

close in interface Channel

removeAllMessages

public void removeAllMessages()

obtainReference

protected MessageReference obtainReference(Routable r)

processMessageBeforeStorage

protected void processMessageBeforeStorage(MessageReference reference)

Give subclass a chance to process the message before storing it internally. Useful to get rid of the REMOTE_ROUTABLE header in a distributed case, for example.

deliver

protected boolean deliver(DeliveryObserver sender,
                          Receiver receiver)
                   throws java.lang.Throwable

Delivery for the channel must be synchronized. Otherwise we can end up with the same message being delivered more than once to the same consumer (if deliver() is called concurrently) or messages being delivered in the wrong order.

Throws:

java.lang.Throwable