net.jini.space

Class AvailabilityEvent

java.lang.Object

java.util.EventObject

net.jini.core.event.RemoteEvent

net.jini.space.AvailabilityEvent

All Implemented Interfaces:

Serializable

public abstract class AvailabilityEvent
extends RemoteEvent

A RemoteEvent marking the transition of an Entry from unavailable to available.

Note, by the time the event is delivered, the Entry whose transition triggered this event may have transitioned to a state where it is no longer visible and/or available.

Since:

2.1

See Also:

JavaSpace05, Serialized Form

Field Summary

Fields inherited from class net.jini.core.event.RemoteEvent

eventID, handback, seqNum, source

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AvailabilityEvent(JavaSpace source, long eventID, long seqNum, MarshalledObject handback, boolean visibilityTransition) Create a new AvailabilityEvent instance.

Method Summary

Methods

Modifier and Type	Method and Description
abstract Entry	getEntry() Returns a copy of the Entry whose transition triggered this event.
abstract Entry	getSnapshot() Returns a snapshot of the Entry whose transition triggered this event.
boolean	isVisibilityTransition() Returns true if the transition that triggered this event was a transition from invisible to visible as well as a transition from unavailable to available, and false otherwise.

Methods inherited from class net.jini.core.event.RemoteEvent

getID, getRegistrationObject, getSequenceNumber

Methods inherited from class java.util.EventObject

getSource, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

AvailabilityEvent

protected AvailabilityEvent(JavaSpace source,
                 long eventID,
                 long seqNum,
                 MarshalledObject handback,
                 boolean visibilityTransition)

Create a new AvailabilityEvent instance.

Parameters:

source - the event source

eventID - the event identifier

seqNum - the event sequence number

handback - the handback object

visibilityTransition - true if this event must also signal a transition from invisible to visible

Throws:

NullPointerException - if source is null

Method Detail

getEntry

public abstract Entry getEntry()
                        throws UnusableEntryException

Returns a copy of the Entry whose transition triggered this event. The returned Entry must be unmarshalled in accordance with the Jini Entry Specification.

Returns:

a copy of the Entry whose transition triggered this event

Throws:

UnusableEntryException - if the Entry can't be unmarshalled in the client. The next call must re-attempt unmarshalling the Entry

getSnapshot

public abstract Entry getSnapshot()

Returns a snapshot of the Entry whose transition triggered this event. Snapshots are defined in section JS.2.6 of the JavaSpaces Service Specification and are an alternative representation of a given Entry produced by a particular space for use with that same space. Passing a snapshot to a space is generally more efficient than passing the original Entry.

Any snapshot returned by this method will meet the same contract as the object returned by passing the result of getEntry to JavaSpace.snapshot.

Generally there is a cost associated with calling the JavaSpace.snapshot method and thus creating a snapshot using that method is usually only worthwhile if the resulting snapshot is used more than once. The cost of invoking this method should be low and should be worthwhile even if the resulting snapshot is used only once.

Returns:

a snapshot of the Entry whose transition triggered this event

isVisibilityTransition

public boolean isVisibilityTransition()

Returns true if the transition that triggered this event was a transition from invisible to visible as well as a transition from unavailable to available, and false otherwise.

Returns:

true if the transition that triggered this event was a transition from invisible to visible as well as a transition from unavailable to available, and false otherwise