[rules-users] rule flow

[Kris Verlaenen]

> Now my understanding is that It should execute rule "Increment"  5 times.. But instead it does it 10 times.

> Is that a normal behavior?



Well, actually, this is expected behaviour, let me try to clarify.

Whenever a RuleSet node, like your "Up" node, is activated, it starts executing activations that are part of that ruleflow-group until no more activations can be found.  Then the node will finish and the flow will continue with the next node.  The problem is that your node, as it is implemented now, automatically increments your Integer 10 times in a row (you can easily test this by just executing this rule without a ruleflow present).  The reason is, once you removed your old integer and inserted a new one, this new Integer will match the same rule again, so your "Up" node will not just continue after one increment, but will increment 10 times (until the integer does not match the <10 pattern of your rule anymore) and then continue to the end.

If I understand what you are trying to do, you should try to make sure that your "Up" rule only increments once.  The best way I could think of right now is adding this at the end of your rule, 

    drools.getWorkingMemory().getAgenda().deactivateRuleFlowGroup("Up");

which will automatically deactivate your ruleflow-group and continue with your execution. But you'll have to use the latest svn code (or 4.0.2 which is released next week), as I found a small problem which would prevent you from doing this in 4.0.1 (.

[Note: While using the no-loop rule attribute for your rule might solve the problem of reactivation of the same rule after an update outside the context of ruleflow, in this case, it will not be sufficient as it will not only block the reactivation of your rule for now but also for all future executions of your "Up" node in your flow, leading to an infinite loop.]

When you are trying to implement a loop, you should also put your join first, and your split at the end.  That way, you will decide what you want to do (in your split) every time AFTER your rule set has been executed.  You can then decide to either go back (to the join in the beginning) or end.  

Also note that doing something like this will become much easier once we add support for ruleflow variables, as you would simply define a variable counter and you would be able to define an action like counter++, and use your ruleflow-groups for executing "real" rules.

Kris

  ----- Original Message ----- 
  From: Manukyan, Sergey 
  To: Rules Users List 
  Sent: Friday, September 14, 2007 9:19 PM
  Subject: [rules-users] rule flow


  Folks,



  Using 4.0.1. Trying to do use rule flow to manage the execution of rules. As I understood in Split node with type XOR I can set conditions for each destination that are executed against facts in working memory. 



  Let's consider I have a rule that executes every time it finds Integer object in memory and increments it.



  rule "Increment"

        ruleflow-group "Up"

        when

              $i : Integer(intValue < 10)

        then 

              System.out.println("INTEGER : " + $i);

              retract($i);

              insert(new Integer($i.intValue() + 1));

  end



  Now, I have the following rule flow in place: 









  The Split to Up arrow has constraint : Integer(intValue < 5)



  And initially I am inserting this fact : insert (new Integer(0))



  Now my understanding is that It should execute rule "Increment"  5 times.. But instead it does it 10 times.



  Is that a normal behavior? Why cannot Split understand that only when there is an Integer(intValue < 5) only then execute rule with ruleflow-group "Up"



  Thanks.



  -Sergey







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