[rules-users] Grouping rules

Wed Feb 6 07:45:08 EST 2008

Great news!

Is this specific to the use of "from" whereas another rule like:-

rule "avoid expense"
    when
        ControlFact( phase == "do expensive call" )
        AnotherFact( someExpensiveTimeConstantFunctionCall == someValue )
    then
        // Do something
    end

Could not have the LHS not evaluated or (to avoid a double negative), would
always have the LHS fully evaluated ;-)

  _____  

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Edson Tirelli
Sent: 06 February 2008 12:29
To: Rules Users List
Subject: Re: [rules-users] Grouping rules

   Yes, it is possible to prevent the evaluation of part of the LHS patterns
by the use of previous constraints and/or the introduction of control facts.

   For instance:

rule "avoid expense"
    when
        ControlFact( phase == "do expensive call" )
        AnotherFact( ) from someExpensiveServiceCall
    then
        // Do something
    end

    In the above example, the "someExpensiveServiceCall" will only be
executed when the previous patterns are matched, i.e., when phase attribute
of the ControlFact has the value "do expensive call".

    []s
    Edson

2008/2/6, Anstis, Michael (M.) <manstis1 at ford.com>: 

I'm not sure as LHS's are evaluated when facts are inserted not when
fireAllRules (or execute) is called.

You can prevent the RHS from activating by using (for lack of a better name)
"flag facts" (but this doesn't solve your problem); for example:-

rule "avoid expense"
    when
        not exists Flag()
        AnotherFact( ) from someExpensiveServiceCall
    then
        // Do something
    end

Don't forget though that if you share LHS patterns across multiple rules
they will share the same nodes in the RETE network, so although you might be
aware that the expensive calls are not required for some rules they might be
required for other rules and hence you'll need to perform the expensive call
when the facts are inserted in order for the other rules to activate.
Perhaps if you better describe your use-case there might be a better
solution.

With kind regards,

Mike

  _____  

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Jai Vasanth
Sent: 05 February 2008 19:35 

To: Rules Users List
Subject: Re: [rules-users] Grouping rules

I had another question on these lines. Is there a way to preven even the LHS
from evaluating for certain cases ? A few of my LHS computation involve some
expensive service calls and I would like to avoid unless and until it is
asolutely necessary.

Thanks 

Jai 

On Feb 1, 2008 8:35 AM, Jai Vasanth <jaivasanth at gmail.com> wrote:

Thanks.  That helped. 

On Feb 1, 2008 7:31 AM, Anstis, Michael (M.) <manstis1 at ford.com> wrote:

Excuse me if you already understand but there is a difference between rule
patterns being evaluated and their consequence running.

Rules LHS are evaluated when objects are inserted into working memory
whereas the consequence fires when you call fireAllRules();

The rules whose activations are executed are those in the given Agenda
Group; thereafter those not in any agenda group execute. So if all rules are
in an Agenda Group you should be OK.

Of course they don't prevent all rule patterns from being checked as objects
are inserted into WM (which has a performance impact) but this is what the
RETE network was designed to optimise. 

You could try another configuration (but I think Agenda Groups are probably
the preference by design). This gives complete isolation - but I haven't
tried it so it might not even be possible ;-)

global WorkingMemory wm;
global RuleBase rbX;

global RuleBase rbY;

rule "Group X"
    when
        Fact( attribute == "condition1" )
    then
        wm = rbX.newStatefulSession();
        wm.fireAllRules();
end

rule "Group Y"
    when
        Fact( attribute == "condition2" )
    then
        wm = rbY.newStatefulSession();
        wm.fireAllRules();
end

Good luck.

Mike

  _____  

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Jai Vasanth

Sent: 01 February 2008 15:07
To: Rules Users List
Subject: Re: [rules-users] Grouping rules

Thanks for responding 
Yes,  I did consider agenda groups, but I thought agenda groups only ordered
execution in a particular fashion, so if Rule "pick group X" fires then it
would make sure that rules in Agenda Group X fire first before the remaining
but the remaining would fire eventually. Is my  understanding correct ?
I am looking for a solution for completely isolating a rule set  conditioned
on an object attribute.

On Feb 1, 2008 12:46 AM, Anstis, Michael (M.) <manstis1 at ford.com> wrote:

What about Agenda Groups?

Rule "pick group X"
when
    Fact( attribute = "condition1" )
then
    drools.setFocus("Group X")
end

Rule "pick group Y"
when
    Fact( attribute = "condition2" )
then
    drools.setFocus("Group Y")
end

Rule "Group X1"
Agenda Group "Group X"
when
    Smurf( )
then
    // Do something
end

Rule "Group X2"
Agenda Group "Group X"
when
    Smurfette( )
then
    // Something else
end

etc

  _____  

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Jai Vasanth
Sent: 31 January 2008 19:45
To: rules-users at lists.jboss.org
Subject: [rules-users] Grouping rules

Hi,

 I am building a system where I would need to fire different sets of rules
based on some attribute in the fact object.  

Here are someways which I thought of, I was wondering if there was something
better than that.

1) I could do this by creating different sessions based on the data attrbute
(different sessions would have different rule packages based on the
attribute)

or 

2) Have all the rules fire (all the different sets of rules) irrespective of
the attribute and have them insert fact new objects into the working memory.
In the second round of rules, collect the (newly made) fact objects  based
on the attribute and take that action.

Thanks 

Jai 

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-- 
  Edson Tirelli
  JBoss Drools Core Development
  Office: +55 11 3529-6000
  Mobile: +55 11 9287-5646
  JBoss, a division of Red Hat @ www.jboss.com 

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