Re: [rules-users] CEP accumulate unclear behavior
Wolfgang, hi again. I've tried your suggestion of the computation separation.
But I tried to use global variable instead of additional fact-accumulator:
/ @Test
public void test1_FireAllRules() throws RuleGeneratorException {
ksession.setGlobal("globalAccum", new ArrayList(Arrays.asList(0)));
ksession.insert(new ServicePerformanceEvent("MyService", 100));
ksession.fireAllRules();
}/
....................................................................
/global java.util.ArrayList *globalAccum*;
rule "HELPER rule to calculate value and put into global variable"
dialect "mvel"
*salience 10*
when
Number( $avg: doubleValue )
from accumulate( $e: ServicePerformanceEvent( $name: serviceName,
$thisDuration: duration),
init( double sum = 0; double count = 0;)
action( if("MyService".equals($name)){sum +=
$thisDuration; count++;})
result( count != 0 ? sum/count : 0 ) );
then
globalAccum.set(0, *$avg + 100*);
System.out.println("--------------------- HELPER RULE salience
10--------------------------------" );
System.out.println("RHS: HELPER RULE: globalAccum = " +
globalAccum.get(0));
end
rule "MAIN rule"
dialect "mvel"
when
$event : ServicePerformanceEvent(*duration >
globalAccum.get(0)*);
then
System.out.println("---------------------- MAIN
RULE--------------------------------" );
System.out.println("RHS: MAIN RULE: $event.duration = " +
$event.duration);
System.out.println("RHS: MAIN RULE: globalAccum = " +
globalAccum.get(0));
end/
The output of invocation was unexpected for me:
--------------------- HELPER RULE salience
10--------------------------------
RHS: HELPER RULE: globalAccum = *200.0*
---------------------- MAIN RULE--------------------------------
RHS: MAIN RULE: $event.duration = *100*
RHS: MAIN RULE: globalAccum = *200.0*
I've found that the order of invocation is:
1 - HELPER rule LHS (calculating avg)
2 - MAIN rule LHS (comparison duration(100) > globalAccum(0))!
3 - HELPER rule RHS (assigning globalAccum with value 200)!
4 - MAIN rule RHS
It was surprise for me, I've expected invocation of Main rule LHS after
Helper rule RHS.
So, as I understand, the only way to achieve desired behavior is insert
helper Fact (insert(new Average($avg)))
in the HELPER rule RHS and then matching this fact into MAIN rule LHS, use
avg from it and further retract it.
--
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