[jboss-jira] [JBoss JIRA] (DROOLS-1227) Drools cannot be configured to expire Events properly

[Mario Fusco (JIRA)]

     [ https://issues.jboss.org/browse/DROOLS-1227?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mario Fusco closed DROOLS-1227.
-------------------------------
    Resolution: Rejected


The engine is working as expected: an event can either have an explicit expiration configured on the event's class or an implicit one calculated on the length of the longest window used on that event. When both these criteria are missing the event has no automatic expiration at all and remains in the engine indefinitely unless it is programmatically retracted. 

> Drools cannot be configured to expire Events properly
> -----------------------------------------------------
>
>                 Key: DROOLS-1227
>                 URL: https://issues.jboss.org/browse/DROOLS-1227
>             Project: Drools
>          Issue Type: Bug
>    Affects Versions: 6.2.0.Final
>         Environment: Windows, Java SE 1.8
>            Reporter: Cristobal Arellano
>            Assignee: Mario Fusco
>            Priority: Critical
>         Attachments: expire_without_temporal_constraint.drl
>
>
> Hello,
> I want to configure Drools (CEP) to expire events when no longer needed. There are two scenarios:
> ==SCENARIO A==
> I configured Event with no explicit expires. In this scenario, if there is a rule with temporal constraints, the expiration is automatically calculated based on the constrains.  If there is a rule with no temporal constraints, the expiration is INFINITE. The following example shows the scenario:
> dialect "mvel"
> declare Event
> @role(event)
> end
> rule "ExampleRule1"
> when
> ( $a : Event(name == "event a") 
> then
> System.out.println("ExampleRule1Triggered");
> end
> rule "ExampleRule2"
> when
> ( $a : Event(name == "event a") ) and
> ( $b : Event((name == "event b") && (this after [1ms, 15s] $a)) )
> then
> System.out.println("ExampleRule2Triggered");
> end
> With the previous Event definition:
> * If only ExampleRule1 loaded, expires INFINITE. Expected expires 0. ERROR?
> * If ExampleRule1 loaded and ExampleRule2 loaded, expires 15s. Expected expires 15. OK!
> To solve this situation a tried the following scenario:
> == SCENARIO B==
> I configured Event with explicit expires. In this scenario, if there is a rule with temporal constraints, the expiration is not taken into account because it is overriden by the explicit expires. The following example shows the scenario:
> dialect "mvel"
> declare Event
> @role(event)
> @expires(0s)
> end
> rule "ExampleRule1"
> when
> ( $a : Event(name == "event a") 
> then
> System.out.println("ExampleRule1Triggered");
> end
> rule "ExampleRule2"
> when
> ( $a : Event(name == "event a") ) and
> ( $b : Event((name == "event b") && (this after [1ms, 15s] $a)) )
> then
> System.out.println("ExampleRule2Triggered");
> end
> With the previous Event definition:
> * ExampleRule1 is triggered and event removed. OK!
> * ExampleRule2 is not triggered inserting two events because the first one expires. ERROR?
> I suppose that SCENARIO B is not factible because explicit expires overrides implicit expires (according to issue DROOLS-586).
> Could you please help me to solve this situation? Should Drools set inferred expiration time to 1ms when there are rules with no temporal constraints?



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