[rules-users] Drools and threads

[Abhay B. Chaware]

Little confused about the third question I had, about rules compilation. I now know that rules are to be compiled.  When I use Guvnor, I have to package the rules ( this is where they are compiled into binary format )  and download the package file and feed it into the production memory / knowledge base using changesets/agents.

But I have also seen examples of drools and also created a few ones where I build the eclipse project and package the entire app as webapp ( .war ) and the rules file is in the classes/lib directory as a .drl file. ( uncompiled ).  And it still works !   Does the drools runtime compile it at runtime ? and then uses it or what ?

Regards,

Abhay Chaware
Sr. Designer | KPIT Cummins Infosystems Ltd | Board: +91 020 6652 5000 | Extn: 2989  | abhay.chaware at kpitcummins.com |www.kpitcummins.com
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From: rules-users-bounces at lists.jboss.org [mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
Sent: Tuesday, May 17, 2011 3:31 PM
To: Rules Users List
Subject: Re: [rules-users] Drools and threads


2011/5/17 Abhay B. Chaware <Abhay.Chaware at kpitcummins.com<mailto:Abhay.Chaware at kpitcummins.com>>
Hi
I have few questions about Drools.
Are rules compiled, partially compiled or interpreted ?

Rules are indeed compiled, but any system where the order of execution
is so highly dynamic has to do some operation in an interpretative mode.


When I call fireAllRules(), does it ( or can it ) create a new thread that runs parallely or the operation is sequential and the caller program HAS TO wait till all rules execution is done ?

No special thread is created. fireAllRules() returns when no more rule activations are to be "fired".

Also, How is the application data integrity guarantied? E.g. what happens when some of the facts are changed in middle of rules being executed .. ? what should happen ?

When a rule activation is executed, the code of the consequence frequently changes one or more facts. This results in reevaluations of rule conditions, etc. This is just the way Drools works.

-W



-abhay

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