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