[rules-users] inserting fact as arraylist in orkingmemory / session

David Sinclair dsinclair at chariotsolutions.com
Wed Jun 10 22:13:10 EDT 2009 

Why not assert all Products into WM as opposed to the array list?? If you
insist on just the array list, something along these lines should do the
trick

rule "Find Product"
    when

        $list : ArrayList()
        Product(productType == "foo") from $list
    then
...


2009/6/10 prasad raju sagi <prasadrajusagi at yahoo.com>

> Hi ,
>
> I am trying to insert fact as arraylist  and then i wanted to get
> the objects from the arraylist based on some condition.
>
> like     Arryalist<Product> fact was inserted into working memory, I
> want to get some product from the arrylist based on condition (
> productType==??).
>
> Is there any solution for this .
>
>
> Thanks
> Prasad Raju Sagi
> Mobile: 847-644-4103
>
>  ------------------------------
> *From:* Greg Barton <greg_barton at yahoo.com>
> *To:* Rules Users List <rules-users at lists.jboss.org>
> *Sent:* Wednesday, June 10, 2009 3:25:39 PM
> *Subject:* RE: [rules-users] Constaint evaluation
>
>
> Correct.  When there are no more instantiations (a rule plus a set of
> objects that match the rule's conditions) on the agenda, then rule firing
> ceases.  With version 5 of drools they added the ability to keep the session
> ready and available to react even when there are no instantiations on the
> agenda, but you must make a separate method call to do that.
> (StatefulSession.fireUntilHalt() instead of fireAllRules())
>
> --- On Wed, 6/10/09, Malenfant, Andre <andre.malenfant at cgi.com> wrote:
>
> > From: Malenfant, Andre <andre.malenfant at cgi.com>
> > Subject: RE: [rules-users] Constaint evaluation
> > To: "Rules Users List" <rules-users at lists.jboss.org>
> > Date: Wednesday, June 10, 2009, 2:55 PM
> > Ok, so now I understand that the
> > "immutable" is really a concept but not necessarily
> > "enforced". So, the rule conditions get evaluated each time
> > the working memory is updated (and not globals) and rules
> > for which the conditions are true at each evaluation will
> > fire. The execution of the rules will end when there is no
> > more rules for which the conditions are true. Am I correct?
> >
> > Thanks
> >
> > -----Original Message-----
> > From: rules-users-bounces at lists.jboss.org
> > [mailto:rules-users-bounces at lists.jboss.org]
> > On Behalf Of Greg Barton
> > Sent: Wednesday, June 10, 2009 3:49 PM
> > To: Rules Users List
> > Subject: RE: [rules-users] Constaint evaluation
> >
> >
> > The ideas is that objects in working memory are those that
> > meant to be tracked: their changes are made visible to the
> > rules via the insert/update/retract methods.  A global
> > is not in working memory, so it's changes cannot be
> > tracked.  You can change the contents of a global all
> > day long and the rules would never be notified.
> >
> > It's a similar concept to threads and
> > synchronization.  You can have unsynchronized access to
> > member variables in a class when in a multithreaded
> > environment, but the results are unpredictable.
> > Likewise, you can use globals in conditions, and change the
> > value of the global as you go, but the results are
> > unpredictable.
> >
> > --- On Wed, 6/10/09, Malenfant, Andre <andre.malenfant at cgi.com>
> > wrote:
> >
> > > From: Malenfant, Andre <andre.malenfant at cgi.com>
> > > Subject: RE: [rules-users] Constaint evaluation
> > > To: "Kris Verlaenen" <Kris.Verlaenen at cs.kuleuven.be>
> > > Cc: "Rules Users List" <rules-users at lists.jboss.org>
> > > Date: Wednesday, June 10, 2009, 2:20 PM
> > > Thanks Kris,
> > >
> > > I will try with code constraints.
> > >
> > > But on the globals subject, I read in the
> > documentation
> > > that one should not use a global in a rule. I have
> > trouble
> > > understanding why. I don't think drools clones the
> > global
> > > object (might not be possible anyway). If my rule
> > > consequences change the state of a global (this usage
> > is
> > > considered valid as per the documentation as well)
> > then what
> > > is the harm of using it in a condition? I could
> > understand
> > > with immutable objects like String but...
> > >
> > > I can change my code to insert that global in the
> > working
> > > memory but I would like to understand why I should do
> > so...
> > > And if I do and the state of that object is changed by
> > a
> > > consequence of my rules, I have to call update? For
> > the same
> > > reason? I guess I am trying to understand the
> > underlying
> > > mechanism.
> > >
> > > Thanks
> > >
> > >
> > > -----Original Message-----
> > > From: Kris Verlaenen [mailto:Kris.Verlaenen at cs.kuleuven.be]
> > >
> > > Sent: Wednesday, June 10, 2009 11:38 AM
> > > To: Rules Users List; Malenfant, Andre
> > > Cc: Rules Users List
> > > Subject: Re: [rules-users] Constaint evaluation
> > >
> > > It depends on what type of constraint you are using.
> > >
> > > If you are using a rule constraint, that constraint
> > will be
> > > evaluated
> > > just the same as normal rules.  This means that the
> > > constraints are
> > > evaluated when data is inserted / updated /
> > removed.
> > > Note that, if you
> > > want to make sure the engine is using up-to-date
> > > information, you must
> > > notify the engine (using update) when you change the
> > data
> > > in the working
> > > memory.  Also note that globals are considered
> > > immutable.  You should
> > > never write rules that depend on the state of a global
> > and
> > > where the
> > > global can be changed.
> > >
> > > If you are using code constraints, the constraint is
> > > evaluated at the
> > > point the code constraint is reached.
> > >
> > > Kris
> > >
> > > Quoting "Malenfant, Andre" <andre.malenfant at cgi.com>:
> > >
> > > > I have some trouble understanding how conditions
> > and
> > > constraints are
> > > > evaluated:
> > > >
> > > > I have a rule flow split node with constraints on
> > a
> > > global object.
> > > > The split node always takes the same path like if
> > the
> > > constraints are
> > > > evaluated at the beginning of the execution of
> > the
> > > process and not
> > > > when the process flow reaches that split node.
> > What I
> > > would expect is
> > > > that the split node constraints takes into
> > account the
> > > state of the
> > > > global object as modified by previous rules in
> > the
> > > flow.
> > > >
> > > > Am I right to think that rules conditions and
> > split
> > > nodes constraints
> > > > are evaluated only when inserting/updating
> > objects in
> > > the working
> > > > memory? The documentation is not really useful
> > (unless
> > > I haven't
> > > > found the appropriate one).
> > > >
> > > > Thanks
> > > >
> > > > André
> > > >
> > > > -----Original Message-----
> > > > From: rules-users-bounces at lists.jboss.org
> > > > [mailto:rules-users-bounces at lists.jboss.org]
> > > On Behalf Of Malenfant,
> > > > Andre
> > > > Sent: Wednesday, June 10, 2009 11:07 AM
> > > > To: Kris Verlaenen
> > > > Cc: Rules Users List
> > > > Subject: RE: [rules-users] Globals in ruleflow
> > > >
> > > > Thanks for trying this for me...
> > > >
> > > > As it turns out, while I was creating a test
> > sample
> > > for you I
> > > > realized
> > > > that my ruleflow was not loading properly and I
> > forgot
> > > to check for
> > > > errors on the builder. Now it works.
> > > >
> > > > Still, the behavior is strange. If my rule
> > doesn't
> > > load and even
> > > > though
> > > > my DRL loaded, my globals were not available.
> > Since
> > > the DRL declared
> > > > the
> > > > same globals it should not have given me that
> > error.
> > > >
> > > > Thanks
> > > >
> > > > -----Original Message-----
> > > > From: Kris Verlaenen [mailto:Kris.Verlaenen at cs.kuleuven.be]
> > >
> > > > Sent: Tuesday, June 09, 2009 5:51 PM
> > > > To: Rules Users List; Malenfant, Andre
> > > > Cc: Rules Users List
> > > > Subject: Re: [rules-users] Globals in ruleflow
> > > >
> > > > Andre,
> > > >
> > > > There should be no problem in using the same
> > global in
> > > both your
> > > > rules
> > > > and processes.
> > > >
> > > > I have tried a simple example as you described
> > but
> > > have not been able
> > > > to
> > > > reproduce the problem.  Could you send me a
> > > self-contained example
> > > > that
> > > > shows the issue?
> > > >
> > > > Kris
> > > >
> > > > Quoting "Malenfant, Andre" <andre.malenfant at cgi.com>:
> > > >
> > > > > I am experimenting with rule flows and I get
> > the
> > > following error:
> > > > >
> > > > > Unexpected global [myglobal]
> > > > >
> > > > > When calling setGlobal on the session.
> > > > >
> > > > > This code works without the workflow
> > (globals
> > > declared in the drl)
> > > > > but
> > > > > fails when I include the rule flow. I
> > declared
> > > the same globals in
> > > > > the
> > > > > rule flow in the header section.
> > > > >
> > > > >
> > _______________________________________________
> > > > > rules-users mailing list
> > > > > rules-users at lists.jboss.org
> > > > > https://lists.jboss.org/mailman/listinfo/rules-users
> > > > >
> > > >
> > > >
> > > >
> > > >
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