[rules-users] RE: Why not retracting?

[Steven Williams]

Hi Mike,

I suggest using the Audit view in eclipse (documented in the help) which
will allow you to see what rules are being added to and removed from the
agenda.

cheers
Steve

On 1/27/07, Anstis, Michael (M.) <manstis1 at ford.com> wrote:
>
>  Thanks Jeff - I guess Rules Engines were common New Years resolution (I'm
> about 2 weeks in too) ;-)
>
> I understood that the LHS side was operated upon when Facts were asserted
> which, I think, creates the RHS Activation in the Agenda. However I also
> thought that if the RHS modified Facts in the Working Memory (by retracting,
> asserting or modifying them) the "Two Phase Execution" (Agenda, Section
> 1.6.5) reassessed which rules needed "firing" (activation?) and hence some
> of the "Cost - calculate cost for 'Stamping process' on a process" rules (in
> my example below) would be disposed of. Is the activation not being dropped
> (perhaps because the "machine == ( m )" condition is still met all be it
> that the Price to which it relates as been disposed of?). I thought we
> were encouraged to write rules that didn't need to be ran in any particular
> order whereas I now find myself having to run some before others?
>
> I'm not ranting at you Jeff, I'm just confused.
>
> Cheers,
>
> Mike
>
>  ------------------------------
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Grimshaw, Jeffrey
> *Sent:* 26 January 2007 16:34
> *To:* Rules Users List
> *Subject:* RE: [rules-users] RE: Why not retracting?
>
>  Hi Michael.  I've only been using JBoss Rules for about 2 weeks, so keep
> that in mind when reading my reply.
>
> The way I understand it works is that facts are evaluated against the LHS
> of all the rules in the ruleset as they are asserted.  That is, when a fact
> is added to the WorkingMemory, the engine determines which rules apply to
> that fact.  You may expect that evaluation to take place when the rules are
> "run".  This may have something to do with the behavior you are seeing.
>
> For more info on what I'm talking about, see section 1.6.4.2 of the user
> docs.
>
> http://labs.jboss.com/file-access/default/members/jbossrules/freezone/docs/3.0.5/html/index.html
>
> Cheers,
>
> --Jeff
>
>
>  ------------------------------
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Anstis, Michael (M.)
> *Sent:* Friday, January 26, 2007 8:08 AM
> *To:* Rules Users List
> *Subject:* [rules-users] RE: Why not retracting?
>
>  By way of an update; if the retraction is made within a different Agenda
> Group the rules work as expected.
>
> However the problem of the retraction having no obvious affect when
> operated within the same Agenda Group remains.
>
> Is this a bug?
>
>    _____________________________________________
>    *From:  * Anstis, Michael (M.)
>    *Sent:  * 26 January 2007 11:32
>    *To:    * 'Rules Users List'
>    *Subject:       * Why not retracting?
>
>    Hello,
>
>    I have the following rules; one removes "Prices" that do not have
>    the required "Economic Level" from working memory, the other calculates a
>    "Costs":-
>
>       rule "Cost - remove prices that do not have the required
>       'Economic Level'"
>       agenda-group "stamping-costs"
>       //salience 1
>       when
>               p : Price ( economicLevel != ( Utilities.makeDate(1,
>       1, 2007) ) )
>       then
>               System.out.println("Retracting "+p.toString());
>               retract(p);
>       end
>
>       rule "Cost - calculate cost for 'Stamping process' on a
>       process"
>       agenda-group "stamping-costs"
>       //salience 2
>       when
>               r : ResourceEntry ( m : machine )
>               //p : Price ( economicLevel == ( Utilities.makeDate(1,
>       1, 2007) ), machine == ( m ) )
>               p : Price ( machine == ( m ) )
>       then
>               Cost cost = new Cost(r, p);
>               cost.setCost((float) (r.getUsage() * p.getRate()));
>               assert(cost);
>       end
>
>    The problem is that the "Cost" rule still works upon ALL "Prices"
>    (even those with an incorrect "Economic Level").
>
>    If I change the line in the "Cost" rule to also check the "Economic
>    Level" the rules work as expected (i.e. "Costs" are only calculated
>    using "Prices" with an "Economic Level" of 01/01/2007).
>
>    I've tried using "salience" levels too (as commented in the above
>    Rules) but this doesn't have any effect either.
>
>    What am I doing wrong?
>
>    Cheers,
>
>    Mike
>
>
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>
>
>


-- 
Steven Williams

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