Hi Leonardo,

the performance problem I thought of meant removing and inserting the facts again and again, if I would remove the facts, that don’t fit the first rule and execute the second rule only on the remaining facts.

The solution you offered, does, what I intend, but the problem is, that I have to create a new class for every rule-pair and I want to use it flexible, without having to create a new class / model for every rule. Is there maybe another way to solve this problem?

Kind regards,

Dominik

Von: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] Im Auftrag von Leonardo Gomes
Gesendet: Dienstag, 12. Oktober 2010 16:37
An: Rules Users List
Betreff: Re: [rules-users] Get rid of redundant conditions in combined rules.

If your problem is performance, don't worry. Conditions evaluation is shared, so in the second rule you won't re-evaluate the entire working memory (to know more:http://www.drdobbs.com/184405218).

If you're worried about not having to repeat the conditions on the second rule, I would create inferred facts when the first rule matches and use then in the second rule + the additional conditions.

Something like:

Rule1:

when

            customer:Customer(town=="London")

then

            insert new LondonCustomer( customer );

Rule2:

when

            london : LondonCustomer(customer.job=="TEACHER")

then

            System.out.println(london.customer.getLname() + " is a teacher");

2010/10/12 Dominik Hüttner <d.huettner@tiq-solutions.de>

Hello everyone,

I’ve got a question. I’m using drools-guvnor to execute some rule-scenarios. I have to solve the following problem: I have an amount of objects in my working memory and can’t remove objects from the working memory in the then-part of the rule. I want to combine two rules, the first rule selects some objects and the second rule checks only these selected objects for additional criteria. I have to use two rules, because I want to report the objects selected in the first rule, too. Now I have implemented this with two rules and in the second rule, the criterias of the first rule are copied to the second rule, my question is, is there a way to get rid of this redundandance?

I have tried this with a rule flow, but the problem is, this always works on the whole working memory, but I can’t remove the not used objects from working memory for performance reasons. Is there another way to solve this problem?

Here is an example for what I intend to do:

Rule1:

when

            customer:Customer(town=="London")

then

            System.out.println(customer.getLname() + " is inhabitant of London");

Rule2:

when

            customer:Customer(town=="London",job=="TEACHER")

then

            System.out.println(customer.getLname() + " is a teacher");

This example illustrates, with the first rule I want to get to know, how many customers are from London and in the second rule I want to know, how many of the London customers are teachers. I want to create a kind of statistics. I have quite a lot of conditions for the first rule, so I don’t want to have them redundantly.

Greetings, Dominik

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