EODelayedObserver

Inherits from: Object

Implements: EOObserving

Package: com.webobjects.eocontrol

Class Description

The EODelayedObserver class is a part of EOControl's change tracking mechanism. It is an abstract superclass that defines the basic functionality for coalescing change notifications for multiple objects and postponing notification according to a prioritized queue. For an overview of the general change tracking mechanism, see "Tracking Enterprise Objects Changes" (page 22) in the introduction to the EOControl Framework.

EODelayedObserver is primarily used to implement the interface layer's associations and wouldn't ordinarily be used outside the scope of a Java Client or Application Kit application (not in a command line tool or WebObjects application, for example). See the EODelayedObserverQueue class specification for general information.

You would never create an instance of EODelayedObserver. Instead, you use subclasses-typically EOAssociations (EOInterface). For information on creating your own EODelayedObserver subclass, see "Creating a Subclass of EODelayedObserver" (page 67).

Constants

EODelayedObserver defines the following int constants to represent the priority of a notification in the queue:

ObserverPriorityImmediate ObserverPriorityFourth

ObserverPriorityFirst ObserverPriorityFifth

ObserverPrioritySecond ObserverPrioritySixth

ObserverPriorityThird ObserverPriorityLater

EODelayedObserver also defines the following int constant to identify the number of defined priorities (8 by default).

ObserverNumberOfPriorities

Interfaces Implemented

EOObserving
objectWillChange

Method Types

Change notification
subjectChanged
objectWillChange
Canceling change notification
discardPendingNotification

Getting the queue and priority
observerQueue priority

Constructors

EODelayedObserver

public EODelayedObserver()

Description forthcoming.

Instance Methods

discardPendingNotification

public void discardPendingNotification()

Sends a dequeueObserver message to the receiver's EODelayedObserverQueue to clear it from receiving a change notification. A subclass of EODelayedObserver should invoke this method when its done observing changes.

See Also: observerQueue

objectWillChange

public void objectWillChange(Object anObject)

Implemented by EODelayedObserver to enqueue the receiver on its EODelayedObserverQueue. Subclasses shouldn't need to override this method; if they do, they must be sure to invoke super's implementation.

See Also: observerQueue, enqueueObserver (EODelayedObserverQueue), objectWillChange (EOObserving)

observerQueue

public EODelayedObserverQueue observerQueue()

Overridden by subclasses to return the receiver's designated EODelayedObserverQueue. EODelayedObserver's implementation returns the default EODelayedObserverQueue.

See Also: defaultObserverQueue (EODelayedObserverQueue)

priority

public int priority()

Overridden by subclasses to return the receiver's change notification priority, one of:

ObserverPriorityImmediate
ObserverPriorityFirst
ObserverPrioritySecond
ObserverPriorityThird
ObserverPriorityFourth
ObserverPriorityFifth
ObserverPrioritySixth
ObserverPriorityLater

EODelayedObserver's implementation returns ObserverPriorityThird. See the EODelayedObserverQueue class specification for more information on priorities.

subjectChanged

public abstract void subjectChanged()

Implemented by subclasses to examine the receiver's observed objects and take whatever action is necessary. EODelayedObserver's implementation does nothing.

`ObserverPriorityImmediate`	`ObserverPriorityFourth`
`ObserverPriorityFirst`	`ObserverPriorityFifth`
`ObserverPrioritySecond`	`ObserverPrioritySixth`
`ObserverPriorityThird`	`ObserverPriorityLater`