Thank you, I like the idea of doing this from a rule, my only concern would be the performance. I was thinking on using an external queue that I would keep up to date by adding a working memory listener. I read that the next release of drools might have some features that might deal better with this situation. thanks --zoly ________________________________ From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Edson Tirelli Sent: Wednesday, February 20, 2008 12:37 PM To: Rules Users List Subject: Re: [rules-users] Question about managing working memory facts If you know what is the timestamp attribute, you can even write a rule... :) rule "garbage collect" salience 100 // use a reasonable salience when $e : Event( $ts : timestamp ) not Event( timestamp < $ts ) Number( intValue > 1000 ) from accumulate( $c : Event(), count( $c ) ) then $retract( $e ); end Not sure if it is the best way, but should work... :) []s Edson 2008/2/19, Zoltan Farkas <zoly(a)daxtechnologies.com&gt;: I am looking to implement a system that has as facts "events" that happen randomly. How is the best way to implement a "garbage collection" mechanism that if the number of "events" in the working memory reaches a limit value will retract the oldest event/s. Thanks --zoly _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users -- Edson Tirelli JBoss Drools Core Development Office: +55 11 3529-6000 Mobile: +55 11 9287-5646 JBoss, a division of Red Hat @ www.jboss.com