[rules-users] Loading rules

[Chris Chen]

I have a simple beginners question about using rules.

Say that I have a set of rules that are static and exist in drl files  
to deal with product pricing.  But then I also have a set of dynamic  
rules stored in the database for different promotions.  Depending on  
the promotion entered or selected, the dynamic rule is retrieved from  
the promotion db row.

Based on this criteria, I have some quick questions that I hope  
someone can help give me answers:

1) Is it good practice to be loading rules, add them to packages,  
compile, and create the RuleBase for every incoming request?  I take  
it that's not a very efficient way to load the rules. It's probably  
better to keep the compiled rule engine available and simply create  
the RuleBase for every incoming request instead.

2) Would it be better then to create two rules engine - 1 for the  
static drl files that do not change and one for the dynamic rules that  
gets refreshed and loaded every time?

3) Another alternative is to load ALL the promotions rules in the DB  
into one rule engine and make sure to check promotion codes on each  
run.  This seems to be efficient.  however, how would I know when the  
DB promotions have changed so that I can reload the rules?  I can  
think of a couple ways.  One is to do periodic cache flushing which  
will refresh the rules engine every once in a while.  The other way is  
to query modification dates and see if any promotions were modified  
since the last time the rules engine was loaded.  There could be a  
third way, which combines the previous two ways together.


I'd like to know if there is some best practice when it comes to  
dynamic rule reloading and what is an efficient and scalable way to do  
this.

Thanks for any thoughts or suggestions!

-Chris