com.ibm.able.rules
Class AblePolicyEngine

java.lang.Object
  com.ibm.able.rules.AbleInferenceEngine
      com.ibm.able.rules.AblePolicyEngine

All Implemented Interfaces:

java.io.Serializable

public class AblePolicyEngine

extends AbleInferenceEngine

implements java.io.Serializable

This class provides the inferencing algorithm for processing a set of rules in a ruleblock using policy evaluation.

The AblePolicyEngine processes AbleAssertionRules and AblePolicyRules 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, AblePolicyRule, Serialized Form

Nested Class Summary

class

AblePolicyEngine.EligibleRuleListEntry_ This class is used to cache a rule with its current business value (priority) and an instance of this class becomes an element in a list of rules that are eligible to fire.

Field Summary

Fields inherited from class com.ibm.able.rules.AbleInferenceEngine

myDebugLevel, myRuleBlock, myRuleSet, myRulesFiredCount, myTracer, myWorkingMemory

Constructor Summary

AblePolicyEngine(AbleRuleSet theRuleSet, AbleLogger theTracer)
Create a new policy inference engine.

AblePolicyEngine(AbleRuleSet theRuleSet, AbleLogger theTracer, AbleRuleBlock theRuleBlock)
Create a new policy inference engine.

Method Summary

java.lang.Object	getControlParameter(java.lang.String theControlParameter) Gets the value of the specified control parameter.
void	infer(AbleRuleBlock theRuleBlock) Fires one rule in the specified ruleblock using policy rule inferencing.
boolean	isRuleBlockValid(AbleRuleBlock theRuleBlock) Determines whether the specified ruleblock is "executable" by examining the rule types and rule object configurations.
protected void	logEligibleRuleList(java.util.Vector theEligibleRuleList) Writes the contents of the eligible rule list (triggered rules) to the Inference trace log.
void	setControlParameter(java.lang.String theControlParameter, java.lang.Object theValue) Sets the value of the specified control parameter.

Methods inherited from class com.ibm.able.rules.AbleInferenceEngine

allocateWorkingMemory, askUser, conditionalRulesValid, evalAntecedentClause, evalAntecedentExpression, evalAssertionClause, evalAssertionRule, evalConditionalRule, evalConsequentClause, evalDoUntilRule, evalDoWhileRule, evalForLoopRule, evalIfThenElseRule, evalPatternMatchRule, evalSwitchRule, evaluateDoActions, evalWhileDoRule, fireEngineBreakpoint, firePropertyChange, getRuleSet, getRulesFiredCount, getWorkingMemory, init, processAssertions, processConsequent, processConsequent, processConsequentClauses, processRuleBlock, reset, resetRuleSet, setControlParameters, setDebugLevel, setInferenceContext, setInferenceContext, setInferenceContext, setRuleSet, setWorkingMemory, startDebugConsole, stopDebugConsole, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

AblePolicyEngine

public AblePolicyEngine(AbleRuleSet theRuleSet,
                        AbleLogger theTracer)

Create a new policy inference engine.

Parameters:

theRuleSet - A ruleset whose rules are to be 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.

AblePolicyEngine

public AblePolicyEngine(AbleRuleSet theRuleSet,
                        AbleLogger theTracer,
                        AbleRuleBlock theRuleBlock)

Create a new policy 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

setControlParameter

public void setControlParameter(java.lang.String theControlParameter,
                                java.lang.Object theValue)
                         throws AbleDataException

Sets the value of the specified control parameter. This engine accepts no control parameters.

Specified by:

setControlParameter in class AbleInferenceEngine

Parameters:

theControlParameter - The name of the control parameter to set. This engine accepts no control parameters.

theValue - The value to be assigned to the specified control parameter.

Throws:

AbleDataException - If the specified control parameter is not supported by this engine.

getControlParameter

public java.lang.Object getControlParameter(java.lang.String theControlParameter)
                                     throws AbleDataException

Gets the value of the specified control parameter. This engine contains no control parameters.

Specified by:

getControlParameter in class AbleInferenceEngine

Parameters:

theControlParameter - The name of the control parameter to get. This engine accepts no names.

Returns:

the current value of the specified control parameter.

Throws:

AbleDataException - If the specified control parameter is not supported by this engine.

isRuleBlockValid

public boolean isRuleBlockValid(AbleRuleBlock theRuleBlock)

Determines whether the specified ruleblock is "executable" by examining the rule types and rule object configurations.

This engine can process only "policy" rules; therefore, the specified ruleblock is invalid if any of the following are present:

• IfThenElse rules
• Predicate rules
• Iteration rules
• Pattern match rules

Specified by:

isRuleBlockValid in class AbleInferenceEngine

Parameters:

theRuleBlock - The rule block to be validated for use with this engine.

Returns:

true, if the ruleset is OK; false, if the ruleset is not executable. Furthermore, all reasons for validation failures are appended to the AbleRuleSet's myIsExReason variable.

infer

public void infer(AbleRuleBlock theRuleBlock)
           throws AbleDataException

Fires one rule in the specified ruleblock using policy rule inferencing.

The infer() method is called by the AbleRuleSet process() method as part of the overall ruleset bean processing sequence.

The order of processing is as follows:

1. Sequentially evaluate all assertion rules in declaration order.
2. Evaluate all enabled policy rules, selecting those whose preconditions are true. Then fire the rule with the most important business value. If several eligible rules have the same "most important" business value, the first rule defined is fired.

Specified by:

infer in class AbleInferenceEngine

Parameters:

theRuleBlock - The ruleblock to be processed.

Throws:

AbleDataException - When any error occurs.

logEligibleRuleList

protected void logEligibleRuleList(java.util.Vector theEligibleRuleList)

Writes the contents of the eligible rule list (triggered rules) to the Inference trace log. Assumes trace is active.