[rules-users] Why no auto-retraction after adding this temporal rule?

[Wolfgang Laun]

Automatic event retraction is something that looks good on glossy flyers.
("Saves your programmers' time, blah, blah...) But as long as you haven't
seen a concise definition of what this feature does (and what it does not),
be very cautious.

That said, your rule RetractionBreaker should fire whenever there is a
MyEvent( key == 'A' ) - no matter how antique - when followed by a
MyEvent( key == 'B' ). This will keep all MyEvent facts from being
retracted. Also, note that the implementation does not try to analyze
beyond
time stamps, i.e., the subtle distinctions of the "key" property are lost.

HTH
-W


On 6 March 2013 20:25, Ladd <ladd at codemettle.com> wrote:

> I'm attaching a small standalone java program to demonstrate this.  The
> code
> should be self explanatory.  But in a nutshell, I'm feeding events into
> this
> rule:
>
> rule averageOverTime
> when
>     $avg: Number() from accumulate (
>          MyEvent( key == 'someKey', $val : value ) over window:time( 200ms
> ),
>          average( $val ) )
> then
>     System.out.println( "--- $avg in then clause is " + $avg );
> end
>
> I set up a loop to feed events in and I do see the rule fire and my
> averages
> print out as I'd expect.  I also set up a session listener to see if events
> are automatically expired/retracted.  And they are.
>
> The trouble begins when I add this rule:
>
> rule RetractionBreaker
> when
>     $a : MyEvent( key == 'A' )
>     MyEvent( key == 'B', this after $a )
> then
>     System.out.println( "--- just saw A followed by B" );
> end
>
> Whether or not I inject events with key 'A' or 'B', no events of any kind
> are ever automatically retracted.
>
> Why is that?
>
> Thanks for helping me understand this!!
>
> - Ladd
>
> NoRetractionTest.java
> <http://drools.46999.n3.nabble.com/file/n4022716/NoRetractionTest.java>
>
>
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/Why-no-auto-retraction-after-adding-this-temporal-rule-tp4022716.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/rules-users/attachments/20130306/ae144bdc/attachment.html