[rules-users] Null Pointer Exception in "org.drools.reteoo.RuleTerminalNode.retractTuple"

Hi - me again :-( Unfortunately I receive a NPE (3.1-M1) as follows (a complete JAR illustrating the problem is available):- **Java Man man=new Man(); Machine machine=new Machine(); Process p = new Process(); wm.assertObject(man); wm.assertObject(machine); wm.assertObject(p); **Rules package drools.debug rule "Rule-1" no-loop true when $p : Process() then System.out.println("DEBUG [Rule-1]---> Add ProcessAlternative to Process"); ProcessAlternative pa = new ProcessAlternative(); $p.addProcessAlternative(pa); assert(pa); modify($p); end rule "Rule-2" no-loop true when $m : Machine() then System.out.println("DEBUG [Rule-2]---> Add Machine to MachineEntry"); MachineEntry me = new MachineEntry(); me.setMachine($m); assert(me); end rule "Rule-3" no-loop true when $me : MachineEntry() $pa : ProcessAlternative() then System.out.println("DEBUG [Rule-3]---> Add MachineEntry to ProcessAlternative"); $pa.addMachineEntry($me); modify($pa); end //rule "Rule-4 (Null Pointer Exception)" //no-loop true //when // $h : Man ( ) // $m : Machine ( ) // $mte : MachineEntry ( machine == $m ) //then // System.out.println("DEBUG [Rule 4]---> Assigned resource"); // $m.setManualResource($h); // modify($m); //end **Output DEBUG [Rule-1]---> Add ProcessAlternative to Process DEBUG [Rule-2]---> Add Machine to MachineEntry DEBUG [Rule-3]---> Add MachineEntry to ProcessAlternative This is what I'd expect. If however rule "Rule-4" is uncommented the output is:- DEBUG [Rule-1]---> Add ProcessAlternative to Process DEBUG [Rule-2]---> Add Machine to MachineEntry DEBUG [Rule-3]---> Add MachineEntry to ProcessAlternative DEBUG [Rule 4]---> Assigned resource DEBUG [Rule-2]---> Add Machine to MachineEntry <-- Why activated? no-loop is true DEBUG [Rule 4]---> Assigned resource <-- Presumably activated as a consequence of above And I receive a NPE with the following stack trace:- java.lang.NullPointerException at org.drools.reteoo.RuleTerminalNode.retractTuple(RuleTerminalNode.java:26 7) at org.drools.reteoo.SingleTupleSinkAdapter.propagateRetractTuple(SingleTup leSinkAdapter.java:38) at org.drools.reteoo.JoinNode.retractTuple(JoinNode.java:217) at org.drools.reteoo.SingleTupleSinkAdapter.propagateRetractTuple(SingleTup leSinkAdapter.java:38) at org.drools.reteoo.JoinNode.retractObject(JoinNode.java:183) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateRetractObject(Comp ositeObjectSinkAdapter.java:369) at org.drools.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java:189) at org.drools.reteoo.Rete.retractObject(Rete.java:171) at org.drools.reteoo.ReteooRuleBase.retractObject(ReteooRuleBase.java:215) at org.drools.reteoo.ReteooWorkingMemory.doRetract(ReteooWorkingMemory.java :76) at org.drools.common.AbstractWorkingMemory.modifyObject(AbstractWorkingMemo ry.java:940) at org.drools.base.DefaultKnowledgeHelper.modifyObject(DefaultKnowledgeHelp er.java:95) at drools.debug.Rule_Rule_4__Null_Pointer_Exception__0.consequence(Rule_Rul e_4__Null_Pointer_Exception__0.java:8) at drools.debug.Rule_Rule_4__Null_Pointer_Exception__0ConsequenceInvoker.ev aluate(Rule_Rule_4__Null_Pointer_Exception__0ConsequenceInvoker.java:24) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:467) at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:431) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemo ry.java:360) I have also encountered NPE in "org.drools.reteoo.AlphaNode.retractObject" when using my actual rules other than these simplifications put together to demonstrate the error (both are caused by a call to "final Activation activation = tuple.getActivation();" returning NULL so I suspect the root cause to be common). Is this a case for a new JIRA entry or have I done something idiotic? With kind regards, Mike