Hi Diana,

   This happens because the order in which things happen. Up to Drools 5.3, Drools apply first filters (a.k.a., alpha constraints or literal constraints), then the sliding windows, then the joins.

   So in your case, 

Notif( specificProblem == "New ONT" ) over window:length(2)

   Drools is first filtering your Notif events with specificProblem == "New ONT", and on those it is applying the sliding window.

   To do what you want, you need to separate the definition of the window from the actual filter:

$last2: List() from collect( Notif() over window:length(2) ) 
$nNewONT : Number() from accumulate ( Notif( specificProblem == "New ONT" ) from $last2, count() )

   I know this is confusing in some cases and for Drools 5.4 we will add explicit window declarations, so that (among other advantages) we reduce surprises like that and completely separate window-scoped filters from rule-scoped filters.

   Edson

2011/10/20 diana-mendes <diana-mendes@hotmail.com>
Hello,


I'm having trouble using sliding length windows. Either I'm implementing
them wrong or I have misunderstood how they're supposed to work.


I have a class named Notif:

*public class Notif implements Serializable{
  ...
  private String specificProblem;
  ...
  public String getSpecificProblem() {
       return specificProblem;
  }

  public void setSpecificProblem(String specificProblem) {
       this.specificProblem = specificProblem;
  }
}*


These Notif's represent my events. I want to know how many Notifs with
specificProblem "New ONT" are there in the last 2 received events.

My .drl file looks like this:


*declare Notif
       @role( event )
end

rule "Rule1"
       when
               $event : Notif()
               $nNewONT : Number() from accumulate (
               Notif( specificProblem == "New ONT" ) over window:length(2), count() )
       then
               System.out.println("In the last 2 events there were "+$nNewONT+" events
'New ONT'");
end*


My test file:

*...
                session.insert(ONTIsInactive1);
                session.insert(newONT1);
                session.insert(ONTIsInactive2);
                session.insert(newONT2);
                session.insert(LOKS1);
                session.insert(LOKS2);
                session.insert(LOKS3);
                session.insert(newONT3);
                session.fireAllRules(); *

As you probably can tell by the names, the events I'm looking for are the
2nd, the 4th and the last one.

But the output I get is:


In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'
In the last 2 events there were 2 events 'New ONT'


The output I'm looking for is:

In the last 2 events there were 0 events 'New ONT' (because the received
event is "ONTIsInactive")
In the last 2 events there were 1 events 'New ONT' (because the last 2
received events are "ONTIsInactive" and "New ONT")
In the last 2 events there were 1 events 'New ONT' (because the last 2
received events are "New ONT" and "ONTIsInactive")
...
and so on...

What am I doing wrong? Any help would be appreciated!
Thanks in advance,

Diana

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  Edson Tirelli
  JBoss Drools Core Development
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