What you report is very unlikely. If this rule would fire when there are no facts of ZZZBean in the working memory, then, referring to $tsb on the right hand side (e.g., by doing $tsb.toString()) should result in a NullPointerException. Please do this and provide the stack trace - but I don't think that you'll be able to do that. Note that the rule will fire *as soon as you insert the first ZZZBean*, because a window of lenght N is actually a window of lenght <= N. -W On 18 October 2011 08:20, eskomk <esko.hujanen(a)ebsolut.fi&gt; wrote:

Hi all, Sorry, I must make a correction the question: the rule fires AFTER one ZZZBean enters the system. After that it fires every time a new ZZZBean enters the system, and every time then fires as many times as there are ZZZBeans in memory. Best regards, Esko ------- Esko Hujanen www.ebsolut.fi -- View this message in context: http://drools.46999.n3.nabble.com/Why-this-rule-fires-immediately-tp34304... Sent from the Drools: User forum mailing list archive at Nabble.com.

First time around I also stumbled over this, especially because the documention fails to describe the actual behaviour, which is certainly not intuitive. All uses of "length n" that I know *do not* include things of length n-1, n-2,... 1. Imagine going into a shop and asking for a belt of length 60" and getting one of 12". A Java array of length 10 isn't 3 or 5 or 9 elements long. Many mathematical procedures that use a data window of length n must avoid shorter samples, or use different treatment, e.g., an initial value problem, or statistical evaluation. -W On 18 October 2011 23:33, Mark Proctor <mproctor(a)codehaus.org&gt; wrote:

Hi all, Sorry, the first rule should read: when $mds : ZZZSensorBean(temperature > 30) not ZZZTracker(profileID == $mds.profileID) then ZZZTracker $tracker = new ZZZTracker(); $tracker.profileID = $mds.profileID; end br Esko -- View this message in context: http://drools.46999.n3.nabble.com/Why-this-rule-fires-immediately-tp34304... Sent from the Drools: User forum mailing list archive at Nabble.com.

Hi W et al., I came up with a following solution. One reason why I came up with this kind of solution is that it is not firing every time when there comes a temperature reading (ZZZBean) in the system (working memory). Would you comment if this solution is viable and if there are any pitfalls ? It seems to work all right, though. Rules involved: TemperatureOver30_settracker Update_tracker_count TemperatureOver30_setalarm TemperatureOver40_setalarm TemprOver30_launch TemprOver40_launch Kill_tracker The tracker is set when get a temperature reading > 30 (TemperatureOver30_settracker). Every subsequent reading is added to tracker's internal list and retracted from working memory (update_tracker_count). Alarm30 is set if average reading from tracker's list is in range > 30 and < 40. Also tracker is retracted (TemperatureOver30_setalarm). Alarm40 is set if average reading from tracker's list is over 40. Also tracker is retracted (TemperatureOver40_setalarm). Intelligent action is launched if Alarm30 is detected, alarm is rectracted (TemprOver30_launch). Another kind of intelligent action is launched if alarm40 is detected, alarm is retracted (TemprOver40_launch). Tracker is retracted if there are over a number of readings (here 10) in tracker's internal list (Kill_tracker), which infers that the average temperature is < 30. Sensor readings and tracker are declared as events, alarms are facts. The saliences are not final, I would like to get comments on that too. rule "TemperatureOver30_settracker" dialect "mvel" no-loop true salience 150 when $tsb : ZZZBean(temperature > 30 && < 40) not TOver30Tracker(profileID == $tsb.profileID) then TOver30Tracker $tracker = new TOver30Tracker(); $tracker.profileID = $tsb.profileID; $tracker.level = 1; retract($tsb); $tracker.sensorBean = $tsb; $tracker.addSensorBean($tsb); insert($tracker); end rule "Update_tracker_count" dialect "mvel" no-loop true salience 100 when $tracker : TOver30Tracker() $tsb : ZZZBean(profileID == $tracker.profileID, this after $tracker) then drools.retract($tsb); $tracker.addSensorBean($tsb); $tracker.count = $tracker.count + 1; drools.update($tracker); end rule "TemperatureOver30_setalarm" dialect "mvel" no-loop true salience 50 when $tracker : TOver30Tracker(count == 5, $prof : profileID) $avg : Number(floatValue > 30 && < 40) from accumulate( ZZZBean( $tempr : temperature, profileID == $prof) over window:length( 5 ) from $tracker.beanList, average( $tempr ) ) then retract($tracker); TOver30Alarm $alarm = new TOver30Alarm(); $alarm.profileID = $prof; $alarm.sensorBean = $tracker.sensorBean; $alarm.sensorBean.temperature = $avg; insert($alarm); end rule "TemperatureOver40_setalarm" dialect "mvel" no-loop true salience 50 when $tracker : TOver30Tracker(count == 5, $prof : profileID) $avg : Number(floatValue > 40) from accumulate( ZZZBean( $tempr : temperature, profileID == $prof) over window:length( 5 ) from $tracker.beanList, average( $tempr ) ) then retract($tracker); TOver40Alarm $alarm = new TOver40Alarm(); $alarm.profileID = $prof; $alarm.sensorBean = $tracker.sensorBean; insert($alarm); end rule "TemprOver30_launch" dialect "mvel" no-loop true when $alarm : TOver30Alarm($prof : profileID) then retract($alarm); // Intelligent action goes here end rule "TemprOver40_launch" dialect "mvel" no-loop true when $alarm : TOver40Alarm($prof : profileID) then retract($alarm); // Intelligent action goes here end rule "Kill_tracker" dialect "mvel" no-loop true salience 999 when $tracker : TOver30Tracker(count > 10) then retract($tracker); end Best Regards, Esko ----- Esko Hujanen www.ebsolut.fi -- View this message in context: http://drools.46999.n3.nabble.com/Why-this-rule-fires-immediately-tp34304... Sent from the Drools: User forum mailing list archive at Nabble.com.