Rule evaluation in Stream Mode (CEP)

[ianEve]

Hello Drools Community,

I'm just trying my first steps with Complex Event Processing (CEP) with Drools Fusion. As a first step I want to implement "stream" as event processing option. For a fist experience, I implemented the rule taken form example 9.4 of Drools 6.4 documentation:

rule "Sound the alarm"
when
    $h: Heartbeat( ) from entry-point "MonitoringStream"
    not( Heartbeat( this != $h, this after[0s,10s] $h ) from entry-point "MonitoringStream" )
then
   System.out.println("Sound the alarm");
end

Within a plain java main-method, I call the fireAllRules-method and wait for 12 seconds. Because of not inserting any Heartbeat-object, after 10 seconds there should be the output "sound the alarm".  But running this small application, leads to nothing: there's no output, no exception, ... Can anybody tell me what I am doing wrong?

This is my implementation of my main-method

public static void main(String[] arguments) {

        KieServices ks = KieServices.Factory.get();
        KieBaseConfiguration config = ks.newKieBaseConfiguration();
        config.setOption(EventProcessingOption.STREAM);

        KieContainer kContainer = ks.getKieClasspathContainer();
        KieBase kBase = kContainer.getKieBase("rules");

        KieSession kSession = kBase.newKieSession();

        kSession.fireAllRules();
        long startTime = System.currentTimeMillis();                
        try {
            Thread.sleep(12000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        long endTime = System.currentTimeMillis();

        System.out.println("Thread slept for: " + (endTime - startTime) / 1000 + " seconds");
    }

Regards, ian

[Mauricio Salatino]

Hi yes,

Your rule is probably activated, but you need to call fireAllRules() again.. or use fireUntilHalt :)

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[ianEve]

Hi, thanks for your answer - but yout advice didn't work either :(

[Mauricio Salatino]

Your rule is not being activated because you didn't insert any Heartbeat Fact 

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[ianEve]

Of course Id did not insert any heartbeat-Fact... because the rule should be executed if no heartbeat fact is inserted

[Michael Anstis]

Your rule says $h: Heartbeat( ) from entry-point "MonitoringStream"

Which means you need a Heartbeat for the rule to activate.

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[Salaboy Mauricio Salatino]

That's not what you rule is stating. 

You rule says: 

If there is a heartbeat and

Not a heartbeat after 10 secs

So there must be at least one heartbeat

Sent from my iPhone

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[ianEve]

You're all right - Sorry!

But adding a Headtbeat - still nothing happens :(

[Salaboy Mauricio Salatino]

Share your class and rules again

Sent from my iPhone

To view this discussion on the web visit https://groups.google.com/d/msgid/drools-usage/7451c422-29e0-4415-9d52-938748facc5d%40googlegroups.com.

[ianEve]

Rule:

rule "Sound the alarm"
when
    $h: Heartbeat( ) from entry-point "MonitoringStream"
    not( Heartbeat( this != $h, this after[0s,10s] $h ) from entry-point "MonitoringStream" )
then
   System.out.println("Sound the alarm");
end

Java-Main:

public static void main(String[] arguments) {

        KieServices ks = KieServices.Factory.get();
        KieBaseConfiguration config = ks.newKieBaseConfiguration();
        config.setOption(EventProcessingOption.STREAM);

        KieContainer kContainer = ks.getKieClasspathContainer();
        KieBase kBase = kContainer.getKieBase("rules");

        KieSession kSession = kBase.newKieSession();

        kSession.insert(new Heartbeat());
        kSession.fireUntilHalt();

[Mauricio Salatino]

Your rule is expecting the hearbeat in a specific Entry-point

you need to do something like 

kSession.getEntryPoint("MonitoringStream").insert(new Heartbeat());

for that to work

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[ianEve]

Thx,

now something happens: but the result is not the desired result. I get the following exception:

Exception in thread "main" java.lang.ClassCastException: org.drools.core.common.DefaultFactHandle cannot be cast to org.drools.core.common.EventFactHandle

Any idea how to solve?

[Mauricio Salatino]

Can you share the whole stacktrace? 

Usually when you deal with events (in this case Heartbeat) you need to mark the class as event by using the declare + type keywords.

Check in the drools doc on how to do that for your Heartbeat class. 

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[ianEve]

This is my Stacktrace:

Exception in thread "main" java.lang.ClassCastException: org.drools.core.common.DefaultFactHandle cannot be cast to org.drools.core.common.EventFactHandle

    at org.drools.core.rule.VariableRestriction$LeftEndRightStartContextEntry.getTimestampFromTuple(VariableRestriction.java:589)
    at org.drools.core.rule.VariableRestriction$TimestampedContextEntry.updateFromTuple(VariableRestriction.java:512)
    at org.drools.core.common.DoubleBetaConstraints.updateFromTuple(DoubleBetaConstraints.java:80)
    at org.drools.core.phreak.PhreakNotNode.doLeftInserts(PhreakNotNode.java:109)
    at org.drools.core.phreak.PhreakNotNode.doNode(PhreakNotNode.java:86)
    at org.drools.core.phreak.RuleNetworkEvaluator.switchOnDoBetaNode(RuleNetworkEvaluator.java:524)
    at org.drools.core.phreak.RuleNetworkEvaluator.evalBetaNode(RuleNetworkEvaluator.java:505)
    at org.drools.core.phreak.RuleNetworkEvaluator.evalNode(RuleNetworkEvaluator.java:341)
    at org.drools.core.phreak.RuleNetworkEvaluator.innerEval(RuleNetworkEvaluator.java:301)
    at org.drools.core.phreak.RuleNetworkEvaluator.outerEval(RuleNetworkEvaluator.java:136)
    at org.drools.core.phreak.RuleNetworkEvaluator.evaluateNetwork(RuleNetworkEvaluator.java:94)
    at org.drools.core.phreak.RuleExecutor.reEvaluateNetwork(RuleExecutor.java:194)
    at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:73)
    at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1007)
    at org.drools.core.common.DefaultAgenda.fireLoop(DefaultAgenda.java:1350)
    at org.drools.core.common.DefaultAgenda.fireUntilHalt(DefaultAgenda.java:1269)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireUntilHalt(StatefulKnowledgeSessionImpl.java:1345)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireUntilHalt(StatefulKnowledgeSessionImpl.java:1324)
    at de.myProject.cep.run.CepHeartbeatExample.main(CepHeartbeatExample.java:25)

[Mauricio Salatino]

Did you tried marking Hearbeat as event? 

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[Mauricio Salatino]

Something like this: 

declare Heartbeat 
    @role( event )

   
end

[ianEve]

Not yet... Gonna continue the next days...

thx a lot for your help :)

[Salaboy Mauricio Salatino]

Check also that you are creating the config but you are not using it as argument when you create the kiebase

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[ianEve]

All right, everything works now :)

Thanks a lot, Salaboy