Hi Enda,

Thanks for the quick response, those are great suggestions and they work as expected. I will dig in and see if I can simplify these rules.

Thanks

 Glenn

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Enda J Diggins
Sent: 10 March 2010 12:55
To: Rules Users List
Subject: Re: [rules-users] Rule looping question

Hi Glenn,

I'm going to start with the looping issue. The quick answer is use lock-on-active instead of no-loop.
This is the important bit of code as far as I'm concerned:

            $tholdBreach : Parameter.Threshold(windowSize == 15,

                  threshold >= $averageUpdateValue) from $param.thresholds

            $firedAlert : AlertInformation(name == $param.name,

                  severity != $tholdBreach.severity)

So, the first time you run through this code you have data like the following:

Thresholds [ Threshold1{severity = MINOR, ...}, Threshold2{severity = CRITICAL, ...} ]

AlertInformation{severity = null, ...}

Execution 1)
 Iteration 1 - AlertInformation.severity != Threshold1.severity
  Result: Set AlertInformation.severity to MINOR

Execution 2)
Iteration 1 - AlertInformation.severity == Threshold1.severity // do nothing
Iteration 2 - AlertInformation.severity != Threshold2.severity
  Result: Set AlertInformation.severity to CRITICAL

This pattern repeats giving you your infinite loop. Does that make sense? You have a list of items you are using for your comparison. The rule will only stop firing when the severity value in AlertInformation matches the severity values on every item in the list. Which can never happen. Lock-on-active will stop the rule from being reactivated as a result of its own execution. This should help but is probably not the best solution. You should look at tightening up your rules some more.

Your other issue, if I understand you correctly, is that you are having trouble with the order the of the list and don't want to have to sort it before adjudication, right?

If so, maybe you could use the 'not' keyword as follows:

            $tholdBreach : Parameter.Threshold(windowSize == 15,

                  threshold >= $averageUpdateValue) from $param.thresholds

            $firedAlert : AlertInformation(name == $param.name,

                  severity != $tholdBreach.severity)

                         not Parameter.Threshold(windowSize == 15, threshold < $tholdBReach, threshold >= $averageUpdateValue) from
                                 $param.thresholds

Here, I am checking to ensure there is not another Threshold with a lower threshold than the one in $tholdBreach that still satisfies our other criteria.

There's probably an easier way, but hopefully that will give you some ideas!

Hope it helps,
Enda

2010/3/10 Glenn Macgregor <gmacgregor@pocketkings.ie>

Hi All,

I am in the process of creating some rules for a POC I am doing using drools, having some issues understanding why I have an infinite loop in a rule.

Rule in question:

rule "Check Parameter Threshold Update Breach"

no-loop true

when

            ParameterUpdateEvent($name : name)

from entry-point "ParamUpdateStream"

            $param : Parameter(name == $name)

            Number($averageUpdateValue : doubleValue)

from accumulate(ParameterUpdateEvent(name == $param.name, $value : value)

                  over window:time(15m)

from entry-point "ParamUpdateStream", average($value))

            $tholdBreach : Parameter.Threshold(windowSize == 15,

                  threshold >= $averageUpdateValue) from $param.thresholds

            $firedAlert : AlertInformation(name == $param.name,

                  severity != $tholdBreach.severity)

then

            System.out.println("Updating alert from '" + $firedAlert.getSeverity() +

"' to '" + $tholdBreach.getSeverity() +

"' alarm: Average update value for " +

                  $param.getName() + " = " + $averageUpdateValue);

            $firedAlert.setSeverity($tholdBreach.getSeverity());

update($firedAlert);

//insert(new AlertInformation($param.getName(), $tholdBreach.getSeverity()));

//modify($firedAlert);

end

I understand what is happening up to the $tholdBreach : Parameter.Threshold line. Each Parameter can have a list of thresholds and what I want this line to do is pick the correct threshold if any are breached. For instance Param1 has 2 thresholds: MINOR and CRITICAL, the MINOR threshold should fire if averageUpdateValue is >= 50, the CRITICAL threshold should fire if averageUpdateValue is >= 40. The first problem I need to solve (in a better way) is getting the correct threshold out of this, the way I do it now is but putting the MINOR threshold in the list before the CRITICAL one. This means that it will be checked first from the line in question. This, to me, is not a good solution. Is there a more deterministic way to do this, I was thinking of somehow using the difference between the threshold and the averageUpdateValue to get the right now but I don’t see how that can work from a rule stand point.

The other question I have is this rule loops infinitely when the averageUpdateValue is below 40 (CRITICAL threshold)  between a MINOR alarm and a CRITICAL alarm and I don’t see why or how because tholdBreach  should always be the CRITICAL alarm and the rule would stop on the next line, but it is alernatly  returning CRITICAL then MINOR which is confusing. To confuse this even more when I comment out the update($firedAlert) and replace that with a retract($firedAlert) and insert(new …) it does not loop.

Any ideas would be great.

Thanks

 Glenn

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Enda J Diggins