Hey again everyone, I seem to be having another problem. When I have a rule like that when A() over window:length(1) B() over window:length(1) then ... I imagine now having two windows of length 1. One always keeping the latest A event and one always keeping the latest B event. And I expect them to update themselves once a new event comes in. But if I have events coming in like this... A1, A2, B1 The rule fires for (A2, B1) then another event B2 is coming in and it fires for (A2,B2) So far so good. Then another event A3 is coming in and the rule fires for (A3,B2) and (A3,B1). Why? Shouldn't the B window only have B2 inside since it arrived and thus fire only for (A3,B2)? I have already been searching for this problem, found this http://drools-java-rules-engine.46999.n3.nabble.com/DROOLS-problem-with-s... but I'm not sure if this is the same problem as mine. Helping me understand this is highly appreciated, since I thought I had completely understood the window behaviour. Thanks in advance. Kind regards Oliver -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Sliding-length-window... Sent from the Drools - User mailing list archive at Nabble.com.