com.ibm.agletx.patterns
Class Notifier

java.lang.Object
  com.ibm.aglet.Aglet
      com.ibm.agletx.patterns.Notifier

All Implemented Interfaces:

java.io.Serializable

public abstract class Notifier

extends Aglet

Create a notifier by calling the static method create. The notifier will get dispatched automatically. The notifier performs successive checks (at its destination) within a specified time duration. Upon every successfull check (one the encounters a change in a local state), it notifies its master. The notifier can be defined (see

 create 

) to complete its job after the first successive check (although its time duration has not been reached yet). If a notifier cannot be dispatched or it encounters an error during a check, it notifies its master and disposed itself.

Version:

1.01 97/10/1

Author:

Danny B. Lange, Yariv Aridor

See Also:

Serialized Form

Field Summary

private java.lang.String	_destination
private double	_duration
private double	_interval
private AgletID	_master
private long	_startingTime
private boolean	_stay
protected java.lang.Object	ARGUMENT The protected variable that carries any arguments for the checks that this notifier performs.
static int	EXCEPTION
static int	EXPIRY
protected java.lang.Object	MESSAGE The protected variable that carries any messages that should go along with the notification back to the subscriber.
private static double	MIN_TIME_OF_DEACTIVATION
static int	NOTIFICATION
private java.lang.String	origin

Fields inherited from class com.ibm.aglet.Aglet

ACTIVE, INACTIVE, MAJOR_VERSION, MINOR_VERSION

Constructor Summary

Notifier()

Method Summary

private boolean	checkTimeout()
static AgletProxy	create(java.net.URL url, java.lang.String source, AgletContext context, Aglet master, java.net.URL destination, double interval, double duration, boolean stay, java.lang.Object argument) Creates a notifier.
protected abstract boolean	doCheck() This method should be overridden to specify the check method for this notifier.
private void	gotoSleep(double hours)
boolean	handleMessage(Message msg) Handles the message form outside.
protected abstract void	initializeCheck() This method should be overridden to specify any intialization before the checks performed by this notifier.
private java.lang.String	makeExceptionMessage(java.lang.String phase, java.lang.Throwable ex)
private void	observeInit()
private void	observeRun()
void	onCreation(java.lang.Object object) Initializes the notifier.
private void	sendRemoteMessage(int type, java.lang.Object data)
private void	start()
private void	startTimer()
private void	waitInHours(double h)

Methods inherited from class com.ibm.aglet.Aglet

addCloneListener, addMobilityListener, addPersistencyListener, clone, deactivate, dispatch, dispatch, dispatchEvent, dispose, exitMonitor, getAgletContext, getAgletID, getAgletInfo, getAudioData, getCodeBase, getImage, getImage, getMessageManager, getProtections, getProxy, getText, notifyAllMessages, notifyMessage, onDisposing, processCloneEvent, processMobilityEvent, processPersistencyEvent, removeCloneListener, removeMobilityListener, removePersistencyListener, run, setProtections, setStub, setText, snapshot, subscribeMessage, suspend, unsubscribeAllMessages, unsubscribeMessage, waitMessage, waitMessage

Methods inherited from class java.lang.Object

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

Field Detail

NOTIFICATION

public static final int NOTIFICATION

See Also:

Constant Field Values

EXPIRY

public static final int EXPIRY

See Also:

Constant Field Values

EXCEPTION

public static final int EXCEPTION

See Also:

Constant Field Values

MIN_TIME_OF_DEACTIVATION

private static final double MIN_TIME_OF_DEACTIVATION

See Also:

Constant Field Values

origin

private java.lang.String origin

_master

private AgletID _master

_destination

private java.lang.String _destination

_interval

private double _interval

_duration

private double _duration

_startingTime

private long _startingTime

_stay

private boolean _stay

MESSAGE

protected java.lang.Object MESSAGE

The protected variable that carries any messages that should go along with the notification back to the subscriber.

ARGUMENT

protected java.lang.Object ARGUMENT

The protected variable that carries any arguments for the checks that this notifier performs.

Constructor Detail

Notifier

public Notifier()

Method Detail

checkTimeout

private boolean checkTimeout()

create

public static AgletProxy create(java.net.URL url,
                                java.lang.String source,
                                AgletContext context,
                                Aglet master,
                                java.net.URL destination,
                                double interval,
                                double duration,
                                boolean stay,
                                java.lang.Object argument)
                         throws java.io.IOException,
                                AgletException

Creates a notifier.

Parameters:

url - the URL of the aglet class.

source - the name of the aglet class.

context - the aglet context in which the notifier should be created.

master - the master aglet.

destination - the URL of the destination.

interval - the time in hours between to checks.

duration - the life time of the notifier.

stay - whether the notifier should remain after a notification.

argument - the

 argument 

object.

Returns:

an aglet proxy for the notifier.

Throws:

AgletException - if the creation fails.

java.io.IOException

doCheck

protected abstract boolean doCheck()
                            throws java.lang.Exception

This method should be overridden to specify the check method for this notifier.

Returns:

boolean result of the check.

Throws:

AgletException - if fails to complete.

java.lang.Exception

gotoSleep

private void gotoSleep(double hours)
                throws AgletException

Throws:

AgletException

handleMessage

public boolean handleMessage(Message msg)

Description copied from class: Aglet

Handles the message form outside.

Overrides:

handleMessage in class Aglet

Returns:

true if the message was handled. Returns false if the message was not handled. If false is returned, the MessageNotHandled exception is thrown in the FutureReply.getReply and AgletProxy.sendMessage methods.

See Also:

FutureReply.getReply(), Message.sendReply(), AgletProxy.sendMessage(com.ibm.aglet.Message)

initializeCheck

protected abstract void initializeCheck()
                                 throws java.lang.Exception

This method should be overridden to specify any intialization before the checks performed by this notifier.

Throws:

AgletException - if fails to complete.

java.lang.Exception

makeExceptionMessage

private java.lang.String makeExceptionMessage(java.lang.String phase,
                                              java.lang.Throwable ex)

observeInit

private void observeInit()
                  throws java.lang.Exception

Throws:

java.lang.Exception

observeRun

private void observeRun()
                 throws java.lang.Exception

Throws:

java.lang.Exception

onCreation

public void onCreation(java.lang.Object object)

Initializes the notifier. Called only the first time this notifier is created. The initialization argument includes the needed parameters for the checks as defined in

 create 

.

Overrides:

onCreation in class Aglet

Parameters:

object - the argument with which the aglet is initialized.

Throws:

AgletException - if the initialization fails.

See Also:

AgletContext.createAglet(java.net.URL, java.lang.String, java.lang.Object)

sendRemoteMessage

private void sendRemoteMessage(int type,
                               java.lang.Object data)
                        throws java.io.IOException,
                               AgletException

Throws:

java.io.IOException

AgletException

start

private void start()

startTimer

private void startTimer()

waitInHours

private void waitInHours(double h)