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

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.
static int	NOTIFICATION

Fields inherited from class com.ibm.aglet.Aglet

ACTIVE, INACTIVE, MAJOR_VERSION, MINOR_VERSION

Constructor Summary

Notifier()

Method Summary

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.
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.
void	onCreation(java.lang.Object object) Initializes the notifier.

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

EXPIRY

public static final int EXPIRY

EXCEPTION

public static final int EXCEPTION

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

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.

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.

handleMessage

public boolean handleMessage(Message msg)

Description copied from class: Aglet

Handles the message form outside.

Overrides:

handleMessage in class Aglet

Following copied from class: com.ibm.aglet.Aglet

Parameters:

msg - the message sent to the 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.

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:

obj - the initialization argument.

Throws:

AgletException - if the initialization fails.