[rules-users] Maintaining state across invocations

[Edson Tirelli]

   What you describe is a CEP scenario, i.e., what Drools Fusion features
were created for.

   Documentation is on the way, but a lot more to do:

https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/docs/drools-fusion/html/index.html

   If you like to mess with the code, take a look at this example I am
implementing. DISCLAMER: the example is not ready, but gives you a quick
view on a few features, like event declaration, sliding windows and entry
points (streams).

http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-examples/drools-examples-fusion/

   Also, for temporal operators, take a look on the javadocs of these
classes:

http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-core/src/main/java/org/drools/base/evaluators/

   []s
   Edson



2009/2/17 ober0n <lili339 at hotmail.com>

>
> Hi, I am a total newb to Drools and am still trying to get a clear picture
> of
> how things work. I have the HelloWorld example running in Eclipse and am
> trying to modify it.
>
> What I'd like to do is write a program that passes single events over a set
> of rules I defined in Drools. Obviously I don't know these events ahead of
> time and I don't know when they will be reported.
>
> Another important point is that I want each of these calls to be a stateful
> transaction, for example:
>
> 1) Some event type A happens and is passed through drools: Rules say to
> ignore the event
>
> 2) Some time later, and event type B happens and is passed through drools:
> Rules say to ignore the event
>
> 3) Then, some time later, another event type A happens and is passed
> through
> drools: This time the rule says to do some action because both event B AND
> event A occurred.
> (NOTE: Here, Drools would need to realize that event B has already occurred
> and needs to take this into account when it invokes the rules. Thus state
> needs to be taken into consideration.)
>
>
> I have been reading the documentation and have seen the stateless and
> stateful sessions in the javadocs. But, I'm not sure if this is what I need
> to accomplish the job. I was discouraged when I found this post:
> http://lists.jboss.org/pipermail/rules-users/2008-February/004688.html
> mentioning that the difference between stateful and stateless was the
> number
> of objects that could be inserted into working memory before calling
> fileAllRules().
>
> >From the examples I've seen, Drools seems to be a simple program you call
> once and the process is terminated (as opposed to a daemon-like program
> that
> is continuously running). (Please correct me if I'm wrong.) Further, I
> understand that Working Memory is where all the facts in Drools are
> contained. I am wondering if these "facts" all disappear once an invocation
> of Drools has finished. Or, do stateful sessions somehow maintain state
> (facts) across Drools invocations?
>
> My best guess is that the Working Memory gets destroyed along with the
> facts
> after an invocation of Drools and that to achieve the state that I want, I
> will need to create some sort of infinite loop to encapsulate an invocation
> of Drools to keep all the facts in Working Memory. Is that true?
>
> I am more than happy to look all of this up myself but need a push in the
> right direction. (Up to this point, I've been looking mainly looking at the
> "JBoss Rules User Guide" and searching on the web.)
>
> Thanks for your help and I would be more that happy to clarify any points.
>
>
> --
> View this message in context:
> http://www.nabble.com/Maintaining-state-across-invocations-tp22068357p22068357.html
> Sent from the drools - user mailing list archive at Nabble.com.
>
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>



-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss, a division of Red Hat @ www.jboss.com
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