ABLE 2.0.0 07/02/2003 10:25:01

com.ibm.able.rules
Class AblePatternMatchLiteEngine

java.lang.Object
  |
  +--com.ibm.able.rules.AbleInferenceEngine
        |
        +--com.ibm.able.rules.AblePatternMatchLiteEngine
All Implemented Interfaces:
java.io.Serializable

public class AblePatternMatchLiteEngine
extends AbleInferenceEngine
implements java.io.Serializable

This class provides the inferencing algorithm for processing a set of pattern match rules in a ruleblock using data-driven or forward chaining. This is a simplified version of the Rete' AblePatternMatchEngine. It will produce identical results but uses a lighter-weight algorithm which may be less efficient than the Rete' engine but will less overhead. It may be appropriate for problems with small numbers of rules and/or working memory objects. In this engine, each pattern match rule is evaluated in each cycle.

The AblePatternMatchLiteEngine processes AbleAssertionRules and AblePatternMatchRules and ignores all others.

The major processing method is infer() which is called by the AbleRuleSet bean as part of the normal bean process() method.

Instances of this class are not directly constructed by the user but are dynamically created by the AbleRuleBlock init() method.

See Also:
AbleRuleSet, AbleRuleBlock, AbleAssertionRule, AblePatternMatchRule, AblePatternMatchEngine, Serialized Form

Field Summary
protected  java.util.Hashtable firedRuleBindingPairs
           
 
Fields inherited from class com.ibm.able.rules.AbleInferenceEngine
myDebugLevel, myRuleBlock, myRuleSet, myRulesFiredCount, myTracer, myWorkingMemory
 
Constructor Summary
AblePatternMatchLiteEngine(AbleRuleSet theRuleSet, AbleLogger theTracer, AbleRuleBlock theRuleBlock)
          Create a new inference engine.
 
Method Summary
protected  void addRuleToConflictSet(java.util.Vector theConflictSet, AblePatternMatchRule theRule)
          Inserts the Rule into the conflict set based on priority.
static java.lang.String Copyright()
          Determine the copyright of this class.
 java.lang.Object getControlParameter(java.lang.String theControlParameter)
          Returns the specified control parameter on the associated inference engine.
 void infer(AbleRuleBlock theRuleBlock)
          Fire the rules in the ruleset using boolean rules of forward chaining inferencing.
protected  boolean isDuplicateFiring(AbleRule theRule, java.util.Vector theBindings)
           
 boolean isRuleBlockValid(AbleRuleBlock theRuleBlock)
          Make sure the current ruleblock is "executable" by this inference engine.
protected  void logConflictSet(java.util.Vector conflictSet)
          Write the contents of the conflict set (triggered rules) to the Inference trace log
protected  void logWorkingMemory()
          Write the contents of working memory out to the Inference trace log
protected  void recordRuleFiring(AbleRule theRule, java.util.Vector theBindings)
           
 void setControlParameter(java.lang.String theControlParameter, java.lang.Object theValue)
          Set the specified control parameter on the associated inference engine.
protected  void setPatternMatchRuleBindings(AblePatternMatchRule theRule)
          Set the bindings on a pattern-match (when-do) rule.
 
Methods inherited from class com.ibm.able.rules.AbleInferenceEngine
askUser, conditionalRulesValid, evalAntecedentClause, evalAntecedentExpression, evalAssertionClause, evalAssertionRule, evalConditionalRule, evalConsequentClause, evalDoUntilRule, evalDoWhileRule, evalForLoopRule, evalIfThenElseRule, evalPatternMatchRule, evaluateDoActions, evalWhileDoRule, fireEngineBreakpoint, firePropertyChange, getRuleSet, getRulesFiredCount, getWorkingMemory, init, processAssertions, processConsequent, processRuleBlock, resetRuleSet, setControlParameters, setDebugLevel, setRuleSet, setWorkingMemory, startDebugConsole, stopDebugConsole, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

firedRuleBindingPairs

protected java.util.Hashtable firedRuleBindingPairs
Constructor Detail

AblePatternMatchLiteEngine

public AblePatternMatchLiteEngine(AbleRuleSet theRuleSet,
                                  AbleLogger theTracer,
                                  AbleRuleBlock theRuleBlock)
Create a new inference engine.
Parameters:
theRuleSet - A ruleset whose context is used for inferencing by this inference engine.

theTracer - A tracer object to which this inference engine can log information. This may be null, in which case no information is logged.

theRuleBlock - A ruleblock whose rules are to be used for inferencing by this inference engine.

Method Detail

isRuleBlockValid

public boolean isRuleBlockValid(AbleRuleBlock theRuleBlock)
Make sure the current ruleblock is "executable" by this inference engine. Only assertion rules and pattern match rules are processed.

The ruleblock is invalid if any of the following are present in the ruleblock:

  • Conditional rule
  • If-then-else rule
  • Predicate rule
  • Iteration rule

    All reasons for validation failures are appended to the AbleRuleSet's myIsExReason variable. If validation fails, the inference engine must call myRuleSet.addIsExReason(java.lang.String) to append the reason.

    Overrides:
    isRuleBlockValid in class AbleInferenceEngine
    Returns:
    true, if the ruleset is OK; false, if the ruleset is not executable.

  • infer

    public void infer(AbleRuleBlock theRuleBlock)
               throws AbleDataException
    Fire the rules in the ruleset using boolean rules of forward chaining inferencing.

    The order of processing is as follows:

    1. Sequentially process all assertion rules in the ruleblock.
    2. Evaluate all pattern match rules using forward chaining and a working memory.
    Overrides:
    infer in class AbleInferenceEngine
    Parameters:
    theRuleBlock - The ruleblock to be processed.

    Throws:
    AbleDataException - When any error occurs.

    setPatternMatchRuleBindings

    protected void setPatternMatchRuleBindings(AblePatternMatchRule theRule)
                                        throws AbleDataException
    Set the bindings on a pattern-match (when-do) rule.

    Procesing is as follows:

    Throws:
    AbleDataException - when the data types are incompatible, or when the relational operator is invalid for the current situation or unrecognized.

    logWorkingMemory

    protected void logWorkingMemory()
    Write the contents of working memory out to the Inference trace log

    logConflictSet

    protected void logConflictSet(java.util.Vector conflictSet)
    Write the contents of the conflict set (triggered rules) to the Inference trace log

    addRuleToConflictSet

    protected void addRuleToConflictSet(java.util.Vector theConflictSet,
                                        AblePatternMatchRule theRule)
                                 throws AbleDataException
    Inserts the Rule into the conflict set based on priority.
    Parameters:
    conflictSet - the Vector to which the rule is added
    theRule - the Rule that needs to be added

    setControlParameter

    public void setControlParameter(java.lang.String theControlParameter,
                                    java.lang.Object theValue)
                             throws AbleDataException
    Set the specified control parameter on the associated inference engine.
    Overrides:
    setControlParameter in class AbleInferenceEngine

    getControlParameter

    public java.lang.Object getControlParameter(java.lang.String theControlParameter)
                                         throws AbleDataException
    Returns the specified control parameter on the associated inference engine.
    Overrides:
    getControlParameter in class AbleInferenceEngine

    recordRuleFiring

    protected void recordRuleFiring(AbleRule theRule,
                                    java.util.Vector theBindings)

    isDuplicateFiring

    protected boolean isDuplicateFiring(AbleRule theRule,
                                        java.util.Vector theBindings)

    Copyright

    public static java.lang.String Copyright()
    Determine the copyright of this class.
    Returns:
    A String containing this class's copyright statement.

    ABLE 2.0.0 07/02/2003 10:25:01

    (C) Copyright IBM Corporation 1999, 2003