edu.mit.sketch.system
Class Scheduler

java.lang.Object
  |
  +--java.util.Observable
        |
        +--edu.mit.sketch.system.Scheduler

Direct Known Subclasses:

StageBasedScheduler

public abstract class Scheduler

extends Observable

The scheduler is in charge of choosing the next action from the queue to execute. This is the base level class that must be subclassed to choose a specific shceduling algorithm. A scheduler has three types of object on the queue to choose from: a item, a KS's conditions, or a KS's action.

Created: Wed Nov 21 15:25:02 2001
Copyright: Copyright (C) 2001 by MIT. All Rights Reserved.

Field Summary

protected Blackboard	m_blackboard The blackboard that holds all the knowledge in the system.
protected BBItemHandler	m_items A collection of the new blackboard items that have appeared as a result of the user's last input stroke or strokes.
protected KnowledgeSourceManager	m_ksManager The ksIndex is responsible for figuring out which KS's are relevent to which triggers.
protected BlackboardSystem	m_system The whole information system including the knowledge sources and the blackboard.
protected LinkedList	m_triggeredKSs

Constructor Summary

Scheduler(BlackboardSystem bbs)

Method Summary

void	addNewBBItem(BBItem bbItem)
protected abstract SchedulerItem	chooseNextItem() Get the next item to be processed.
protected abstract boolean	doneProcessing() Answer the question: are we done processing the input we have and ready for more new user input?
Collection	getRecentItems()
protected boolean	hasUnprocessed()
protected boolean	isStackEmpty()
protected SchedulerItem	popStack()
protected abstract SchedulerItem	postProcessingStep() Ask if this particular scheduler has a post processing process to run.
protected abstract boolean	readyToProcess() Look at the new user inputs to the blackboard (in the BBItemHandler) and decide whether they are worth processing at this stage.
protected void	triggerKSs(Collection kss)

Methods inherited from class java.util.Observable

addObserver, clearChanged, countObservers, deleteObserver, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

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

Field Detail

m_items

protected BBItemHandler m_items

A collection of the new blackboard items that have appeared as a result of the user's last input stroke or strokes.

m_system

protected BlackboardSystem m_system

The whole information system including the knowledge sources and the blackboard. This system does simple operations on the data flow, like add new user inputs to the system and as the UI to display stuff (Although this might be a job for the scheduler.)

m_blackboard

protected Blackboard m_blackboard

The blackboard that holds all the knowledge in the system. This is a convenience pointer since the blackboard can be accessed through the blackboard system.

m_ksManager

protected KnowledgeSourceManager m_ksManager

The ksIndex is responsible for figuring out which KS's are relevent to which triggers. This is a part of the blackboard system so we could just get it from there, but this is a conveneince pointer.

m_triggeredKSs

protected LinkedList m_triggeredKSs

Constructor Detail

Scheduler

public Scheduler(BlackboardSystem bbs)

Method Detail

readyToProcess

protected abstract boolean readyToProcess()

Look at the new user inputs to the blackboard (in the BBItemHandler) and decide whether they are worth processing at this stage.

doneProcessing

protected abstract boolean doneProcessing()

Answer the question: are we done processing the input we have and ready for more new user input?

chooseNextItem

protected abstract SchedulerItem chooseNextItem()

Get the next item to be processed. This procedure may also talk to the KS manager to see if there are more KSs that should be run.

postProcessingStep

protected abstract SchedulerItem postProcessingStep()

Ask if this particular scheduler has a post processing process to run.

addNewBBItem

public void addNewBBItem(BBItem bbItem)

getRecentItems

public Collection getRecentItems()

isStackEmpty

protected boolean isStackEmpty()

popStack

protected SchedulerItem popStack()

triggerKSs

protected void triggerKSs(Collection kss)

hasUnprocessed

protected boolean hasUnprocessed()