[rules-users] lock-on-active documentation

[Edson Tirelli]

   Wolfgang,

   The Rete algorithm eagerly reevaluate rules when changes are made to
data, does not matter if the rules belong to the active group or not. If a
rule in a non-active group is fully matched, it will be added to the agenda.
The difference is: rules in non-active groups are not allowed to *fire*, so
they will sit in the agenda until they are canceled by other changes to data
or their group becomes active, allowing them to fire.

   Now, what lock-on-active does is: it prevents the fully matched rules on
active groups that contain lock-on-active to add the activation to the
agenda.

   Regarding your question of [4], does not matter who makes the change to
data. Even changes made by the application are caught by this scenario. The
scenario is: if the rule would add an activation of itself to the agenda,
but it has lock-on-active true and its group is active, the activation will
be discarded instead of added.

   You are right. Docs are not clear. Thank you for helping.

   Edson

2009/3/15 Wolfgang Laun <wolfgang.laun at gmail.com>

> From Drools-5.0.0, Expert, 7.8.1. Sentence numbers added by me:
>
> [1] when a ruleflow-group becomes active or an agenda-group receives the
> focus
> any rules that have lock-on-active set to try cannot place activations onto
> the
> agenda, the rules are matched and the resulting activations discarded.
> [2] This is a stronger version of no-loop.
> [3] It's ideally for calculation rules where you have a number of rules
> that
> will modify a fact and you don't want any rule re-matching and firing.
> [4] In summary fire these currently active rules and only these rules, no
> matter how the data changes, do not allow any more activations for the
> rules
> with the attribute set to true.
> [5] When the ruleflow-group is no longer active or agenda-group loses the
> focus those rules with lock-on-active set to true can once again add
> activations onto the agenda.
>
>
> [4] says that activations "for the rules with the attribute set to true"
> are
> disallowed. This is confusing or even in contradiction with [1], which I
> understand to mean that WM updates done by the RHS of a rule X with
> lock-on-active==true don't result in any activations. (Of course, this
> includes activations of X itself.)
>
> [5] is absolutely confusing: How can rules in a group that isn't active
> or doesn't have the focus can add activations - irrespective of its
> lock-on-active setting?
>
> [1] s/when/When/, s/try/true/
>
> I would create a JIRA, but I'd like to be sure what to suggest for a fix.
> -W
>
>
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-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss, a division of Red Hat @ www.jboss.com
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