Language and System Ergonomics

http://www.slideshare.net/MarkProctor/property-reactive-ruleml-2013Saturday, 13 July 13

Extending an Object-Oriented RETE Network with fine-grained

Reactivity to Property ModificationsMark Proctor, Mario Fusco and David Sottara

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AgendaThe ProblemProperty Reactive

The techniqueRelated WorkThe ImplementationBenchmarking

Conclusion

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The ProblemLoop Control

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The problemReactive rule based systems are hard to write

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Too Much!!!!Reactive rule based systems are hard to write

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Reactive Rulerule <rule_name> <attribute><value> when <conditions> then <actions>end

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Patterns

Person(age >= 18)field name restriction

constraintobject type

pattern

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CashFlow Ruleselect * from AccountPeriod ap, Account acc, Cashflow cfwhere cf.type == CREDIT and acc.accountNo == cf.accountNo cf.date >= ap.start and cf.date <= ap.end

rule “increase balance for AccountPeriod Credits” when ap : AccountPeriod() acc : Account() cf : CashFlow( type == CREDIT, accountNo == acc.accountNo, date >= ap.start && <= ap.end ) then acc.balance += cf.amount; end

acc.balance += cf.amount

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Loop Problemrule “Salary award for min 2 years service” when e : Employee( lengthOfService > 2 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

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Loop Problemrule “Salary award for min 2 years service” no-loop when e : Employee( lengthOfService > 2 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

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Loop Problemrule “Salary award for min 2 years service” no-loop when e : Employee( lengthOfService > 2 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

rule “Salary award for min 8 years service” no-loop when e : Employee( lengthOfService > 8 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

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Loop Problemrule “Salary award for min 2 years service” when e : Employee( lengthOfService > 2 ) not SalaryMin2Years( employee == e )then modify( e ) { setSalary( e.getSalary() * 1.05 ) }; insert ( new SalaryMin2Years(e) );end

rule “Salary award for min 8 years service” when e : Employee( lengthOfService > 8 ) not SalaryMin8Years( employee == e )then modify( e ) { setSalary( e.getSalary() * 1.05 ) }; insert ( new SalaryMin8Years(e) );end

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Loop Problemrule “Year End” when d : ChangeDate( ) e : Employee( )then modify( e ) { lengthOfService( d.getYear() - e.getStartYear() ) };end

rule “Salary award for min 8 years service” when e : Employee( lengthOfService > 8 ) not SalaryMin8Years( employee == e )then modify( e ) { setSalary( e.getSalary() * 1.05 ) }; insert ( new SalaryMin8Years(e) );end

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RefractionThis term comes from the neurobiological observation of a refractory period for a neuron, which means that the neuron is not able to fire immediately without first going through a relaxation process. In a similar way, OPS5 will not allow the same instantiation in the conflict set from firing twice in a row. This prevents the inference engine from entering into an infinite loop.

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W3C RIF RefractionRefraction

When a rule instance is fired, it is removed from the conflict set (and thus will not be created again even its condition part remains true), unless one of the objects in its condition part is modified again. In the later case, the repeatability concept determines how the rule instance is treated

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W3C RIF RefractionRepeatability

After the execution of a rule instance, the rule instance is removed from the conflict set by the refraction. Later on, if one of the objects in the condition part is modified and if the rule evaluates to true, the repeatability controls whether if the rule instance can be created again.

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Loop Problem (Refraction)rule “Salary award for min 2 years service” repeatable false when e : Employee( lengthOfService > 2 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

rule “Salary award for min 8 years service” repeatable false when e : Employee( lengthOfService > 8 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

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AAAAAAhhhhhhhhhh

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Property ReactiveThe Technique

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Annotate Class@PropertyReactivepublic class Employee { int salary; int lengthOfService

// getters and setters below}

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Loop Problem Fixedrule “Salary award for min 2 years service” when e : Employee( lengthOfService > 2 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

rule “Salary award for min 8 years service” when e : Employee( lengthOfService > 8 )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

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@Watchrule “Salary award for min 2 years service” when e : Employee( salary < 1000, lengthOfService > 2 ) @Watch( !salary )then modify( e ) { setSalary( e.getSalary() * 1.05 ) };end

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@Watchrule “Record Salary Changes” when e : Employee( ) @Watch( salary )then insert( new SalaryChange( e, e.getSalary() );end

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@Watch@Watch( salary, lengthOfService, age )

@Watch( * )

@Watch( !* )

@Watch( *, !salary )

@Watch( !*, salary )

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Good FormGood Function

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Property ReactiveRelated Work

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Related WorkCLIPS COOL

Uses Triples for propertiesProperty Reactivity is just a useful side effect, not an intention.No @Watch like capability

JessSlot Specific no literature on implementationNo @Watch like capability

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Related WorkYES/OPS

“New Trigger Conditions”Simple @Watches with “!” symbolNo literature on implementation

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Property ReactiveThe Implementation

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Class@PropertyReactivepublic class Bar { int a; // 1 int b; // 2 int c; // 4 int d; // 8 int e; // 16 int f; // 32

// getters and setters below}

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Propagation Masks@PropertyReactivepublic class Bar { int a; // 1 int b; // 2 int c; // 4 int d; // 8 int e; // 16 int f; // 32

}

modify ( bar ) { a = 1 }// 000001

modify ( bar ) { a = 1, c = 1 }// 000101

modify ( bar ) { a = 1, c = 1, f = 1 }// 100101

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Network Masksrule R1 when Foo( $v : v ) bar : Bar( c >= 1, a >= 1, e >= $v ) then ... end

Bar

a => 1

c => 1

e => V

b1

a1

a2

Foo

declared : 000100inferred : 010101

declared : 000001inferred : 010101

declared : 010000inferred : 010101

modify ( bar ) { a = 1, c = 1 }// 000101

modify ( bar ) { b = 1, d = 1 }// 010010

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Network Masksrule R1 when Foo( $v : v ) Bar( c >= 1, a >= 1, e >= $v )

rule R2 when Foo( $v : v ) Bar( c >= 1, d >= 1, b >= $v )

Bar

a => 1

c => 1

d => 1

e => V b => V

a1

a2 a3

Network ShareHere

declared : 001000inferred : 011111

declared : 000001inferred : 010101

declared : 010000inferred : 010101

declared : 001000inferred : 001110

declared : 000010inferred : 001110

b1 b2Saturday, 13 July 13

Network Masksrule R1 when Foo( $v : v ) Bar( c >= 1, a >= 1, e >= $v )

rule R2 when Foo( $v : v ) Bar( c >= 1, d >= 1, b >= $v )

rule R3 when Dummy( ) Bar( c >= 1 ) @Watch( f, d, !c )

Bar

a => 1

c => 1

d => 1

e => V b => V

@watch(f, d, !c)

b1 b2 b3

a1

a2 a3

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Network MasksBar

a => 1

c => 1

d => 1

e => V b => V

a1

a2 a3

Network ShareHere

declared : 001000inferred : 111111

declared : 000001inferred : 010101

declared : 010000inferred : 010101

declared : 001000inferred : 001110

declared : 000010inferred : 001110

b1 b2

@watch(f, d, !c)

b3

declared : 101000inferred : 101000

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Network MasksBar

a => 1

c => 1

d => 1

e => V b => V

a1

a2 a3

Network ShareHere

declared : 001000inferred : 111111

declared : 000001inferred : 010101

declared : 010000inferred : 010101

declared : 001000inferred : 001110

declared : 000010inferred : 001110

b1 b2

@watch(f, d, !c)

b3

declared : 101000inferred : 101000

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Property ReactiveBenchmark

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Hardware i7-2820QM@2.30GHz Quad core CPU with HyperThreading8Gb of RAM, OpenJDK 1.7 Ubuntu Quetzal 64bit operating system

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Classes A

int a1, int b1B

int b2, int b2

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Benchmark #1

rule R0 when $a: A( $a1 : a1 < 10 ) then modify( $a ) { setA2( $a1 + 1 ) }; end

rule R0 no-loop when $a: A( $a1 : a1 < 10 ) then modify( $a ) { setA2( $a1 + 1 ) }; end

insert 1mill AInitial a1, a2 set to 1No-loop

2.275±0.080sProperty Reactive

2.265 ± 0.047sGain

0.44%Saturday, 13 July 13

Benchmark #4rule R3 whena: A( a1 < 10 )b: B( b1 < a.a1 )... x: X( x1 < w.w1, x2 > a.a2 )then modify( a ) { setA2( c.getC2() + 1 ) };end

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Benchmark #4 Results

rule R3 whena: A( a1 < 10 )b: B( b1 < a.a1 )... x: X( x1 < w.w1, x2 > a.a2 )then modify( a ) { setA2( c.getC2() + 1 ) };end

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Conclusion

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Conclusion - AchievedEnabled and Disabled at a Class level for flexibilityComplimentary and additional to RIF Refraction and Repeatable, adding finer grained control.@Watch provides even further declarative control.Keeps rules clean.

Not Polluted with control logic.Not any slower, and can give increased gains, by avoiding wasted join evaluations.Cost pushed to compile time, works with dynamic rules addition and removal.Good Form, Good Function

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Conclusion - Future Work@Watch

Can we push all or part of the @Watch higher up the alpha networkDiscriminates earlier, better performance

Further flexibility to control propagations based on rising and falling edges

onMatch, onReMatch, onUnmatch

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Zen-like Calmness

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