2:48 p.m.
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(a)cgi.com> wrote:
From: Malenfant, Andre <andre.malenfant(a)cgi.com>
Subject: RE: [rules-users] Constaint evaluation
To: "Kris Verlaenen" <Kris.Verlaenen(a)cs.kuleuven.be>
Cc: "Rules Users List" <rules-users(a)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@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(a)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(a)lists.jboss.org
> [mailto:rules-users-bounces@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@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(a)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(a)lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
>
>
>
>
> Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
2:55 p.m.
New subject: Constaint evaluation
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(a)lists.jboss.org [mailto:rules-users-bounces@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(a)cgi.com> wrote:
From: Malenfant, Andre <andre.malenfant(a)cgi.com>
Subject: RE: [rules-users] Constaint evaluation
To: "Kris Verlaenen" <Kris.Verlaenen(a)cs.kuleuven.be>
Cc: "Rules Users List" <rules-users(a)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@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(a)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(a)lists.jboss.org
> [mailto:rules-users-bounces@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@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(a)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(a)lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
>
>
>
>
> Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
5698
days inactive
5698
days old
1 comments
2 participants
participants (2)
-
Greg Barton -
Malenfant, Andre