(reposting to a more appropriate list) I'm starting to expirament with Drools and Drools Fusion and am running into some problems using sliding windows. I'm using Drools 5.1.1 with a fairly simple configuration. I have one rule: package net.wlauer.DroolsEngine import net.wlauer.DroolsEngine.Event import java.util.ArrayList declare Event @role(event) @expires(30s) end rule TestWindow when $up : Event (type == "linkup", $inf : extra) $window : ArrayList () from collect ( Event (extra == $inf) over window:length(2)) $down : Event (type == "linkdown", this before $up) from $window then channels["up"].send($up); end I expect this rule to fire whenever it sees a "linkup" event immediately after a "linkdown" event for the same value of extra. (If you can suggest a better way to write this, I would appreciate it). My sample program simply inserts four Events, calling fireAllRules once all the inserts have been completed. What I'm seeing instead of my expected results is the exception: Exception in thread "main" java.lang.ClassCastException: org.drools.common.DefaultFactHandle cannot be cast to org.drools.common.EventFactHandle at org.drools.base.evaluators.BeforeEvaluatorDefinition$BeforeEvaluator.evaluateCachedLeft(BeforeEvaluatorDefinition.java:333) at org.drools.rule.VariableRestriction.isAllowedCachedLeft(VariableRestriction.java:110) at org.drools.rule.VariableConstraint.isAllowedCachedLeft(VariableConstraint.java:115) at org.drools.common.SingleBetaConstraints.isAllowedCachedLeft(SingleBetaConstraints.java:142) at org.drools.reteoo.FromNode.checkConstraintsAndPropagate(FromNode.java:274) at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:138) at org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189) at org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:64) at org.drools.reteoo.AccumulateNode.evaluateResultConstraints(AccumulateNode.java:662) at org.drools.reteoo.AccumulateNode.assertLeftTuple(AccumulateNode.java:181) at org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189) at org.drools.reteoo.SingleLeftTupleSinkAdapter.createAndPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:138) at org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:148) at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59) at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:145) at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:450) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:368) at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:190) at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:145) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1174) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1123) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:917) at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:251) at net.wlauer.DroolsEngine.NonSpringRulesEngine.main(NonSpringRulesEngine.java:71) being treated as an event-type fact, but I don't see where that could be happening. Am I doing something obviously wrong? I've tried marking ArrayList as an event type, but that didn't change the behavior. Any insight you can give me would be appreciated. -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/sliding-window-proble... Sent from the Drools - User mailing list archive at Nabble.com.