com.ibm.agletx.patterns
Class Slave

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

All Implemented Interfaces:

java.io.Serializable

public abstract class Slave

extends Aglet

Create a slave by calling the static method create. The slave will get dispatched automatically.
Given an itinerary, the slave is travelled from one destination to another while repeating a local computation in every destination. Then, a final result is delivered to the slave's Master (the creator of the slave). During its tour the slave aglet skips destinations which are not available.
When a slave:
1) completes its tour.
2) encounters an error during a local computation.
3) cannot be further dispatched to yet unvisited destinations.
it immediately returns to its origin host and submits the intermediate result.

Version:

1.0 96/08/18

Author:

Danny B. Lange, Yariv Aridor

See Also:

Serialized Form

Field Summary

protected java.lang.Object	ARGUMENT The protected variable that carries an argument for the local task performed in every destination.
private SlaveAgletItinerary	itin
private AgletID	master
protected java.lang.Object	RESULT The protected variable that accumulates the results of the local task performed in every destination.

Fields inherited from class com.ibm.aglet.Aglet

ACTIVE, INACTIVE, MAJOR_VERSION, MINOR_VERSION

Constructor Summary

Slave()

Method Summary

static AgletProxy	create(java.net.URL url, java.lang.String name, AgletContext context, Aglet master, java.util.Vector itinerary, java.lang.Object argument) Create a slave.
protected abstract void	doJob() This method should be overridden to specify the local task of the slave.
AgletID	getMaster()
private AgletProxy	getMasterProxy(AgletID master, Aglet aglet)
java.lang.String	getOrigin() Return the address of origin of the Slave (i.e.
boolean	handleMessage(Message msg) Handles the message form outside.
protected abstract void	initializeJob() This method should be overridden to specify initialization part for the job of the slave.
void	onCreation(java.lang.Object object) Initialize the slave.
private void	onError(SlaveError error)
private void	onReturn()
private void	print(java.lang.String text)

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

master

private AgletID master

itin

private SlaveAgletItinerary itin

RESULT

protected java.lang.Object RESULT

The protected variable that accumulates the results of the local task performed in every destination.

ARGUMENT

protected java.lang.Object ARGUMENT

The protected variable that carries an argument for the local task performed in every destination.

Constructor Detail

Slave

public Slave()

Method Detail

create

public static AgletProxy create(java.net.URL url,
                                java.lang.String name,
                                AgletContext context,
                                Aglet master,
                                java.util.Vector itinerary,
                                java.lang.Object argument)
                         throws java.io.IOException,
                                AgletException

Create a slave.

Parameters:

url - the url of the aglet class.

name - the name of the aglet class.

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

master - the master aglet.

itinerary - A vector of addresses of destinations

argument - the

 argument 

object.

Returns:

an aglet proxy for the slave.

Throws:

AgletException - if initialization fails.

java.io.IOException

doJob

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

This method should be overridden to specify the local task of the slave.

Throws:

AgletException - if fails to complete.

java.lang.Exception

getMaster

public AgletID getMaster()

getMasterProxy

private AgletProxy getMasterProxy(AgletID master,
                                  Aglet aglet)
                           throws AgletException

Throws:

AgletException

getOrigin

public java.lang.String getOrigin()

Return the address of origin of the Slave (i.e. the host from which it started its tour).

Returns:

the address of the origin.

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)

initializeJob

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

This method should be overridden to specify initialization part for the job of the slave.

Throws:

AgletException - if fails to complete.

java.lang.Exception

onCreation

public void onCreation(java.lang.Object object)

Initialize the slave. It is called only the first time the slave is created. The initialization argument includes three elements: (1) the master aglet and (2) the Slave's itinerary, and (3) an argument for the local task.

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)

onError

private void onError(SlaveError error)

onReturn

private void onReturn()

print

private void print(java.lang.String text)