Your question is funny. First you ask if Drools is capable of managing complex rules and then you mention examples of extremely simple rules? :)

     Drools is FOL complete and so can represent any well formed First Order Logic expression. Anyway, I will use this message to advertise some of the temporal reasoning features that we have on Drools 5 for the benefit of anyone interested.
   
     There are several ways of authoring such rules, depending on how you model your problem domain. One possible way of doing them is:

#1:
rule "If a customer login within 5 minutes from two different locations, mark the user invalid."
when
     $l1 : CustomerLogin( )
     $l2 : CustomerLogin( userId == l1.$id, location != $l1.id, timestamp after[0s, 5m] $l1.timestamp )
then
     // mark user as invalid
end

In the previous example I assumed both login objects would be in working memory, but you can easily query for the previous login in an external datasource, pulling the data from the previous login on-demand for the reasoning cycle.

#2:
rule "If the customer location is not on a list of valid locations, mark the user invalid"
when
      $l : CustomerLogin( location not memberOf $validLocations )
then
      // mark the user invalid
end
 
In the above rule, I assume the valid locations list is a global list, but you can as easily model locations as being facts on your working memory or a service end point that you can call to validate the location.

#3:
rule “Customer login from more than 5 locations in the last one month”
when
    $customer : Customer( $id : id )
    $locations : Set( size > 5 ) from accumulate(
                     CustomerLogin( customerId == $id, $loc : location ) over window:time( 30d ),
                     collectSet( $loc ) )
then
    // do something as the customer logged in from more than 5 locations in the last 30 days
end

In the previous rule I decided to use sliding windows, just to show how that feature can be used to simplify rules, but again, there are several ways of doing it.

I strongly recommend you read Drools manual.

http://www.jboss.org/drools/documentation.html

Cheers,
Edson



2009/5/19 Bhushan Bhangale <bhushan_bhangale@kaleconsultants.com>

Hi,

 

I recently came across Drools. I gone through the documentation and the examples provide are quite simple. I want to know if it can be really applied to complex real world problems.

 

Take for example,

 

If a customer login within 5 minutes from two different locations, mark the user invalid.

How can I write the above rule in drools? I have the data when the user last logged in and the data of current login. You can say two objects.

 

May be my understanding is wrong but looks like based on rule I have to pass all the required data. How can then at real time new rules can be added?

 

For example,

 

If the customer location is not on a list of valid locations, mark the user invalid.

 

For the above rule I need to pass a list of valid locations as well.

 

Now how about “Customer login from more than 5 locations in the last one month”?

 

Thanks

Mr. Bhangale Bhushan
Associate Manager
Kale Consultants Ltd.
bhushan_bhangale@kaleconsultants.com
tel: +91 (0)206 608 3777
http://www.kaleconsultants.com

 

 

 

 


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 Edson Tirelli
 JBoss Drools Core Development
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