Re: JESS: general question about using module to control rule execution

[Ernest Friedman-Hill]

Salience is considered bad form for two reasons: first, because it's  
considered bad form, in general, to try to force the engine to fire  
rules in a particular order; and second, it negatively impacts  
performance.  The truth is, though, if it's the most sensible or  
elegant alternative in a particular application, there's really no  
reason not to use it.

If you want to not fire any rules in module B until all rules in  
module A have had a chance to fire, then rather than putting the focus  
statements into a rule, you probably want to put them into the same  
code that calls "run" -- i.e.,

(focus A)
(run)
(focus B)
(run)




On Oct 12, 2009, at 3:44 PM, Felix Chan wrote:

Hi,

I have a general question how to control execution using modules.

I have business rules that apply at the country (US) level, and  
rules that apply at state level. What I would like to do is to apply  
country-level rules first and then state-level rules second. The  
state-level rules will overwrite some of the facts that were  
modified or asserted as a result of the country-level rules.

I do NOT want to have any state-level rules applied before country- 
level rules have a chance to fire.

I can group all the country-level rules in module COUNTRY and state- 
level rules in module STATE. I understand that I can put (focus  
STATE) on the RHS to move from one module to another to control  
execution flow.

Question: What should I do to ensure that I will switch to the STATE  
module only after ALL APPLICABLE country-level rules have been  
applied (fired)?

I can use salience, but the book says that it's bad form. So I am  
wondering if I should module.

Thanks.

Felix

---------------------------------------------------------
Ernest Friedman-Hill
Informatics & Decision Sciences, Sandia National Laboratories
PO Box 969, MS 9012, Livermore, CA 94550
http://www.jessrules.com







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