org.xmlBlaster.engine.distributor.plugins
Class ConsumableQueuePlugin

java.lang.Object
  org.xmlBlaster.engine.distributor.plugins.ConsumableQueuePlugin

All Implemented Interfaces:

java.util.EventListener, I_MsgDistributor, I_SubscriptionListener, I_ConnectionStatusListener, I_Plugin

public class ConsumableQueuePlugin
extends java.lang.Object
implements I_MsgDistributor, I_ConnectionStatusListener

ConsumableQueuePlugin

Author:

Michele Laghi

Field Summary

private Global	global
(package private) boolean	isReady
(package private) boolean	isRunning
private static java.util.logging.Logger	log
private static java.lang.String	ME
private java.lang.Object	mutex
private PluginInfo	pluginInfo
private ServerScope	serverScope
private java.lang.String	topicId

Fields inherited from interface org.xmlBlaster.engine.I_SubscriptionListener

PRIO_01, PRIO_05, PRIO_10

Constructor Summary

ConsumableQueuePlugin()
The default constructor.

Method Summary

void	distribute(MsgUnitWrapper msgUnitWrapper) This method should not throw any exception so it is responsability of the plugin developer to catch Throwable and make the necessary error handling.
private boolean	distributeOneEntry(MsgUnitWrapper msgUnitWrapper, MsgQueueHistoryEntry entry, java.util.List subInfoList) Distributes one single entry taken from the history queue.
private UpdateReturnQosServer	doDistribute(SubscriptionInfo sub, MsgQueueUpdateEntry entry) Enforced by the I_DistributionInterceptor interface.
private I_DispatchManager	getDispatchManager(SubscriptionInfo subscriptionInfo)
java.lang.Integer	getPriority() The priority by which it will be invoked.
java.lang.String	getType()
java.lang.String	getVersion()
private void	givingUpDistribution(SubscriptionInfo sub, MsgUnitWrapper msgUnitWrapper, MsgQueueEntry entry, java.lang.Throwable e)
void	init(Global global, PluginInfo pluginInfo) Initializes the plugin
(package private) void	processHistoryQueue() Takes entries from the history queue and distributes it to the dispatcher framework until there are entries available or until the dispatcher framework is alive.
void	shutdown() It removes all subscriptions done on this topic
void	subscriptionAdd(SubscriptionEvent e) Invoked when a subscriber is added to the TopicHandler
void	subscriptionRemove(SubscriptionEvent e) Invoked when a subscriber is removed from the TopicHandler
void	toAlive(I_DispatchManager dispatchManager, ConnectionStateEnum oldState) Event arriving from one DispatchManager telling this plugin it can start distribute again.
void	toAliveSync(I_DispatchManager dispatchManager, ConnectionStateEnum oldState)
void	toDead(I_DispatchManager dispatchManager, ConnectionStateEnum oldState, XmlBlasterException xmlBlasterException)
void	toPolling(I_DispatchManager dispatchManager, ConnectionStateEnum oldState)
private void	toRunning() Invoked on status changes when it shall start to distribute entries.

Methods inherited from class java.lang.Object

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

Field Detail

ME

private static final java.lang.String ME

See Also:

Constant Field Values

isReady

boolean isReady

isRunning

boolean isRunning

global

private Global global

log

private static java.util.logging.Logger log

pluginInfo

private PluginInfo pluginInfo

serverScope

private ServerScope serverScope

topicId

private java.lang.String topicId

mutex

private java.lang.Object mutex

Constructor Detail

ConsumableQueuePlugin

public ConsumableQueuePlugin()

The default constructor. Currently does nothing.

Method Detail

toRunning

private void toRunning()

Invoked on status changes when it shall start to distribute entries. This can either happen on publish, on subscribe or when a dispatcher becomes alive again. This method is synchronized to avoid more threads running concurrently (see processHistoryQueue).

distribute

public void distribute(MsgUnitWrapper msgUnitWrapper)

Description copied from interface: I_MsgDistributor

This method should not throw any exception so it is responsability of the plugin developer to catch Throwable and make the necessary error handling.

Specified by:

distribute in interface I_MsgDistributor

Parameters:

msgUnitWrapper - the entry to distribute

See Also:

Invoked by the TopicHandler on publish or subscribe. Starts the distributor thread and returnes immeditately. From here distribution is handled by another thread.

init

public void init(Global global,
                 PluginInfo pluginInfo)
          throws XmlBlasterException

Initializes the plugin

Specified by:

init in interface I_Plugin

Throws:

XmlBlasterException

getType

public java.lang.String getType()

Specified by:

getType in interface I_Plugin

getVersion

public java.lang.String getVersion()

Specified by:

getVersion in interface I_Plugin

shutdown

public void shutdown()
              throws XmlBlasterException

It removes all subscriptions done on this topic

Specified by:

shutdown in interface I_Plugin

Throws:

XmlBlasterException - if an exception occurs. The exception is handled by the RunLevelManager depending on how the plugin has been configured with the action:

<action do='STOP' onShutdownRunlevel='2' sequence='5' onFail='resource.configuration.pluginFailed'> If onFail is defined to something, the RunLevelManager will stop.

getDispatchManager

private final I_DispatchManager getDispatchManager(SubscriptionInfo subscriptionInfo)

subscriptionAdd

public void subscriptionAdd(SubscriptionEvent e)
                     throws XmlBlasterException

Invoked when a subscriber is added to the TopicHandler

Specified by:

subscriptionAdd in interface I_SubscriptionListener

Parameters:

subscriptionInfo -

Throws:

XmlBlasterException

subscriptionRemove

public void subscriptionRemove(SubscriptionEvent e)
                        throws XmlBlasterException

Invoked when a subscriber is removed from the TopicHandler

Specified by:

subscriptionRemove in interface I_SubscriptionListener

Parameters:

subscriptionInfo -

Throws:

XmlBlasterException

toAlive

public void toAlive(I_DispatchManager dispatchManager,
                    ConnectionStateEnum oldState)

Event arriving from one DispatchManager telling this plugin it can start distribute again.

Specified by:

toAlive in interface I_ConnectionStatusListener

toPolling

public void toPolling(I_DispatchManager dispatchManager,
                      ConnectionStateEnum oldState)

Specified by:

toPolling in interface I_ConnectionStatusListener

toDead

public void toDead(I_DispatchManager dispatchManager,
                   ConnectionStateEnum oldState,
                   XmlBlasterException xmlBlasterException)

Specified by:

toDead in interface I_ConnectionStatusListener

xmlBlasterException - Can be null

toAliveSync

public void toAliveSync(I_DispatchManager dispatchManager,
                        ConnectionStateEnum oldState)

Specified by:

toAliveSync in interface I_ConnectionStatusListener

processHistoryQueue

void processHistoryQueue()

Takes entries from the history queue and distributes it to the dispatcher framework until there are entries available or until the dispatcher framework is alive.

distributeOneEntry

private boolean distributeOneEntry(MsgUnitWrapper msgUnitWrapper,
                                   MsgQueueHistoryEntry entry,
                                   java.util.List subInfoList)

Distributes one single entry taken from the history queue. This method is strict, it does not throw any exceptions. If one exception occurs inside this method, the distribution is interrupted, a dead letter is generated and the entry is removed from the history queue.

Parameters:

subInfoList - contains the SubscriptionInfo objects to scan. Once the message is processed by one of the dispatchers, the associated SessionInfo is put at the end of the list to allow some simple load balancing mechanism.

Returns:

true if the entry has been removed from the history queue. This happens if the entry could be sent successfully, or if distribution was given up due to an exception. It returns false if none of the subscribers were able to receive the message (to tell the invoker not to continue with distribution until the next event.

givingUpDistribution

private void givingUpDistribution(SubscriptionInfo sub,
                                  MsgUnitWrapper msgUnitWrapper,
                                  MsgQueueEntry entry,
                                  java.lang.Throwable e)

doDistribute

private UpdateReturnQosServer doDistribute(SubscriptionInfo sub,
                                           MsgQueueUpdateEntry entry)
                                    throws XmlBlasterException

Enforced by the I_DistributionInterceptor interface. It sends sychronously to the DispatchWorker this entry.

Throws:

XmlBlasterException

getPriority

public java.lang.Integer getPriority()

Description copied from interface: I_SubscriptionListener

The priority by which it will be invoked. Lower numbers are invoked first on subscribe and last on unsubscribe.

Specified by:

getPriority in interface I_SubscriptionListener

Returns:

See Also:

I_SubscriptionListener.getPriority()