lime
Class Reaction

java.lang.Object
  lime.Reaction

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

LimeSystemReaction, LocalizedReaction, RegisteredReaction, UbiquitousReaction

public abstract class Reaction

extends java.lang.Object

implements java.io.Serializable

The superclass of all reactions. A reaction is specified by:

• a template, which is used to match tuples in the shared tuple space;
• a reaction listener, which contains the code that must be executed when the a tuple matching the template appears in the tuple space and thus the reaction must be actually fired;
• and a reaction mode that is specified by one of the following constants:
  • ONCE: When a tuple satisfying the reaction template appears in the tuple space, the reaction is fired once and then the reaction is removed automatically from the reactive program.
  • ONCEPERTUPLE: When a tuple satisfying the reaction template appears in the tuple space, the reaction is fired, and will never fire again for that tuple. However, the reaction remains installed. So, if multiple tuples enable the reaction, the reaction is fired once for each of them.
  Reactions are registered with a Lime tuple space by passing a Reaction object to either the addStrongReaction or the addWeakReaction methods. However, since the class Reaction is abstract, only instances of its subclasses can exist. In particular, addStrongReaction accepts only instances of LocalizedReaction while addWeakReaction can also accept instances of UbiquitousReaction. In both cases, when the reaction is fired, the reactsTo method of the ReactionListener object associated with the reaction is automatically invoked by the system.

  The aforementioned methods addStrongReaction and addWeakReaction return a RegisteredReaction object to the user, that can be used to later deregister the reaction from the shared tuple space. A RegisteredReaction object is identical to the original Reaction object used for registration, but provides additional information, part of which is available to the user for bookkeeping purposes (e.g., the name of the tuple space the reaction has been registered with) and part of which is managed by the system.

  Version:

  1.0 alpha

  Author:

  Amy L. Murphy, Gian Pietro Picco

  See Also:

  LocalizedReaction, UbiquitousReaction, LimeSystemReaction, ReactionListener, RegisteredReaction, LimeTupleSpace, Serialized Form

  Field Summary

  private LimeTemplate	limeTmpl
  private ReactionListener	listener
  private short	mode
  static short	ONCE The reaction is fired once and then it is removed automatically from the reactive program.
  static short	ONCEPERTUPLE The reaction is fired, and will never fire again for a given tuple, but remains registered.
  (package private) PendingUponListener	pendUponListener
  private lights.interfaces.ITuple	template

  Constructor Summary

  (package private)	Reaction()
  (package private)	Reaction(lights.interfaces.ITuple template, ReactionListener listener, short mode)
  (package private)	Reaction(LimeTemplate lt, ReactionListener listener, short mode)

  Method Summary

  Location	getCurrentLocation() Get the current location associated with the reaction.
  AgentLocation	getDestinationLocation() Get the destination location associated with the reaction.
  (package private) lights.interfaces.ITuple	getLimifiedTemplate() Get the template associated with the reaction...without delimifying it.
  ReactionListener	getListener() Get the reaction listener associated with the reaction.
  short	getMode() Get the reaction mode.
  LimeTemplate	getTemplate() Get the template associated with the reaction.
  java.lang.String	toString()

  Methods inherited from class java.lang.Object

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

  Field Detail

  ONCE

  public static final short ONCE

  The reaction is fired once and then it is removed automatically from the reactive program.

  See Also:

  Constant Field Values

  ONCEPERTUPLE

  public static final short ONCEPERTUPLE

  The reaction is fired, and will never fire again for a given tuple, but remains registered. So, if multiple tuples enable the reaction, the reaction is fired for each of them.

  See Also:

  Constant Field Values

  limeTmpl

  private LimeTemplate limeTmpl

  template

  private lights.interfaces.ITuple template

  listener

  private ReactionListener listener

  pendUponListener

  PendingUponListener pendUponListener

  mode

  private short mode

  Constructor Detail

  Reaction

  Reaction()

  Reaction

  Reaction(LimeTemplate lt,
           ReactionListener listener,
           short mode)

  Reaction

  Reaction(lights.interfaces.ITuple template,
           ReactionListener listener,
           short mode)
     throws lights.interfaces.TupleSpaceException

  Method Detail

  getTemplate

  public final LimeTemplate getTemplate()

  Get the template associated with the reaction.

  getLimifiedTemplate

  final lights.interfaces.ITuple getLimifiedTemplate()

  Get the template associated with the reaction...without delimifying it. (used in PendingUponListener to reinstall the reaction) NOTE: may not have to do this once the reinstallation of the reaction is changed. (20Jan99)(alm)

  getListener

  public final ReactionListener getListener()

  Get the reaction listener associated with the reaction.

  getMode

  public final short getMode()

  Get the reaction mode.

  getCurrentLocation

  public final Location getCurrentLocation()

  Get the current location associated with the reaction.

  getDestinationLocation

  public final AgentLocation getDestinationLocation()

  Get the destination location associated with the reaction.

  toString

  public java.lang.String toString()