[rules-users] Large number of rules in Drools
Wolfgang Laun
wolfgang.laun at gmail.com
Tue Jan 10 15:37:32 EST 2012
Assuming that the remaining 19998 rules are of the same kind, there is a
lot of data in these rules, and only very little logic. Ignoring the issue
of "Olympia" being one of the cities not being "Seattle", we have the
problem of matching a triplet of <field,state,city> from a Student fact so
that we can store one or more Subjects in Student.subjects.
Imagine that you have objects of type Inscribe containing a triplet of
field, state, city and the pertaining List<Subject>. Then you could write a
single (!) rule
rule register
when
$stu: Student ( $f: field, $s: state, $c: city )
$ins: Inscribe( field==$f, state==$s, city==$c )
then
$stu.setSubjects( $ins.getSubjects() );
end
BTW: Why do you use equals with state? Using "==" should be possible here,
too.
And, of course, matching ~20000 different triplets to facts of a single
type isn't really RBS fodder. You can design a simple Java program that
achieves this goal, assuming you can come up with a straightforward
representation of the <field,state,city;subject+> mapping.
-W
2012/1/10 Shweta1986 <shweta.a.thakkar at gmail.com>
> My rules are as follows.
> rule "rule1"
> salience -2
> dialect "mvel"
> when
> stud : Student ( field == "ARTS", state.equals("WA"))
> then
> java.util.List subList = new java.util.ArrayList();
> Subject subject = new Subject();
> subject.setName("ABC");
> subject.setFees(33454);
> subject.duration(4);
> subList.add(subject);
>
> subject = new Subject();
> subject.setName("XYZ");
> subject.setFees(33454);
> subject.duration(4);
> subList.add(subject);
>
> stud.setSubjects(subList);
> end
> rule "rule2"
> salience -100
> dialect "mvel"
> when
> stud : Student ( field == "ARTS", state.equals("WA") , city ==
> "SEATTLE"))
> then
> java.util.List subList = new java.util.ArrayList();
> Subject subject = new Subject();
> subject.setName("ABC");
> subject.setFees(33454);
> subject.duration(4);
> subList.add(subject);
>
> subject = new Subject();
> subject.setName("XYZ");
> subject.setFees(33454);
> subject.duration(4);
> subList.add(subject);
>
> stud.setSubjects(subList);
> end
>
>
>
> Student is the main object and it contains List of Subjects. here the way
> I am using the salience because
> if the input us shweta, ARTS, WA,Olympia it matched rule1
> but if the input is shweta, ARTS, WA, Seattle it matches 1 and 2 but i
> want the rule 2 to be executed so salience.
>
> I am using StatelessKnowledge Session and also the resource change scanner.
> I execute one rule at a time and the scanner poll interval is 1 hour.
> When I started with 100 rules I was using "PK" as my source in
> changeSet.xml but when the rules grew to 20K I was not able to build the
> rules in Guvnor UI and hence I started using "DRL" as source.
>
> The way I generate drl is using a script which converts the csv to drl
> format.
> I copy the drl to the text area in techincal rules and save it. ( this
> copy is also paiful so I asked that if there is an upload drl file unlike
> the import drl file)
> In changeset I give the path to the url in webdav
> /guvnor/org.drools.guvnor.Guvnor/webdav/packages/StudentRules/StudentRules.drl
>
> I am not sure if I am doing it the right way. Please suggest.
>
> Thanks,
> Shweta
>
> On Mon, Jan 9, 2012 at 11:58 PM, laune [via Drools] <[hidden email]<http://user/SendEmail.jtp?type=node&node=3648661&i=0>
> > wrote:
>
>> Salience is just one way to force the evaluation of a condition before
>> others. In fact, using salience throughout is just a way of re-creating a
>> sequence of plain old if statements using a rules engine.
>>
>> I'm not going to waste my time and yours by elaborating on possible
>> alternatives unless you come up with a detailed description of your rules,
>> and how you run your rules engine: fact insertion, calls to fire, etc.
>>
>> -W
>>
>> 2012/1/10 Shweta1986 <[hidden email]<http://user/SendEmail.jtp?type=node&node=3647015&i=0>
>> >
>>
>>> I am not sure I understand that. What is the other option for this case.
>>> Why would simple rules not work for 20 K rules. Am I missing something. I
>>> cannot use database to store my rules. Drools also gives me salience which
>>> I need for my usecase.
>>>
>>> On Thu, Jan 5, 2012 at 11:29 PM, laune [via Drools] <[hidden email]<http://user/SendEmail.jtp?type=node&node=3646449&i=0>
>>> > wrote:
>>>
>>>> 2012/1/6 Shweta1986 <[hidden email]<http://user/SendEmail.jtp?type=node&node=3637255&i=0>
>>>> >
>>>>
>>>>> And my rules are very simple it is like if string comparison then set
>>>>> that's it..
>>>>>
>>>> This doesn't really warrant the use of a rule based system. If keeping
>>>> this logic out of the application or an easy maintenance of these if-then's
>>>> are your main goals, there are other ways. I've already hinted at this,
>>>> with the idea of providing the information embedded in similar rules as
>>>> data.
>>>> -W
>>>>
>>>>
>>>>
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