3:53 a.m.
Hello,
why does such a rule always loop? Even if no-loop is used?
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
The full code of my test application and drl is attached.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl
package com.sample
import com.sample.DroolsTest.MyFactBean1;
import com.sample.DroolsTest.MyFactBean2;
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
4:23 a.m.
I have to quickly recheck the documentation by I think you have to write "no-loop
true". Just writing no-loop defaults to false I guess.
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On
Behalf Of Przemyslaw Rózycki
Sent: Tuesday, February 10, 2009 3:24 PM
To: Rules Users List
Subject: [rules-users] Rules with from always loops (Drools 4.0.7)
Hello,
why does such a rule always loop? Even if no-loop is used?
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
The full code of my test application and drl is attached.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl
MASTEK LTD.
Mastek is in NASSCOM's 'India Top 20' Software Service Exporters List.
In the US, we're called MAJESCOMASTEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Opinions expressed in this e-mail are those of the individual and not that of Mastek
Limited, unless specifically indicated to that effect. Mastek Limited does not accept any
responsibility or liability for it. This e-mail and attachments (if any) transmitted with
it are confidential and/or privileged and solely for the use of the intended person or
entity to which it is addressed. Any review, re-transmission, dissemination or other use
of or taking of any action in reliance upon this information by persons or entities other
than the intended recipient is prohibited. This e-mail and its attachments have been
scanned for the presence of computer viruses. It is the responsibility of the recipient to
run the virus check on e-mails and attachments before opening them. If you have received
this e-mail in error, kindly delete this e-mail from desktop and server.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4:31 a.m.
Thanks for answer, Vikrant, but I don't think so. I have always used
no-loop without any additions and it worked (when I didn't use from).
BTW, if you comment a condition with from, then the rule does not loop.
I also checked with "no-loop true" and result is the same.
Best regards,
Przemek
Vikrant Yagnick pisze:
I have to quickly recheck the documentation by I think you have to
write "no-loop true". Just writing no-loop defaults to false I guess.
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On
Behalf Of Przemyslaw Rózycki
Sent: Tuesday, February 10, 2009 3:24 PM
To: Rules Users List
Subject: [rules-users] Rules with from always loops (Drools 4.0.7)
Hello,
why does such a rule always loop? Even if no-loop is used?
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
The full code of my test application and drl is attached.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl
MASTEK LTD.
Mastek is in NASSCOM's 'India Top 20' Software Service Exporters List.
In the US, we're called MAJESCOMASTEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Opinions expressed in this e-mail are those of the individual and not that of Mastek
Limited, unless specifically indicated to that effect. Mastek Limited does not accept any
responsibility or liability for it. This e-mail and attachments (if any) transmitted with
it are confidential and/or privileged and solely for the use of the intended person or
entity to which it is addressed. Any review, re-transmission, dissemination or other use
of or taking of any action in reliance upon this information by persons or entities other
than the intended recipient is prohibited. This e-mail and its attachments have been
scanned for the presence of computer viruses. It is the responsibility of the recipient to
run the virus check on e-mails and attachments before opening them. If you have received
this e-mail in error, kindly delete this e-mail from desktop and server.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_______________________________________________
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https://lists.jboss.org/mailman/listinfo/rules-users
3:12 a.m.
Hello,
Doesn't really anyone have any logical explanation of why such a rule loops?
To remind the rule:
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
If I don't use 'from' everything is fine.
I really didn't find in a documentation, that 'from' causes any special
behaviour of the rule looping.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl
Przemysław Różycki pisze:
Thanks for answer, Vikrant, but I don't think so. I have always
used
no-loop without any additions and it worked (when I didn't use from).
BTW, if you comment a condition with from, then the rule does not loop.
I also checked with "no-loop true" and result is the same.
Best regards,
Przemek
Vikrant Yagnick pisze:
> I have to quickly recheck the documentation by I think you have to
> write "no-loop true". Just writing no-loop defaults to false I guess.
>
> -----Original Message-----
> From: rules-users-bounces(a)lists.jboss.org
> [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Przemyslaw
> Rózycki
> Sent: Tuesday, February 10, 2009 3:24 PM
> To: Rules Users List
> Subject: [rules-users] Rules with from always loops (Drools 4.0.7)
>
> Hello,
>
> why does such a rule always loop? Even if no-loop is used?
>
> rule "Hello World"
> no-loop
> when
> $fact1 : MyFactBean1( )
> $fact2 : MyFactBean2( ) from $fact1
> then
> System.out.println("Fired!!!");
> update($fact1);
> end
>
> The full code of my test application and drl is attached.
>
> Best regards,
> --
> Przemysław Różycki
> AMG.net, A Bull Group Company
> ul. Łąkowa 29
> 90-554 Łódź
> www.amg.net.pl
>
>
> MASTEK LTD.
> Mastek is in NASSCOM's 'India Top 20' Software Service Exporters List.
> In the US, we're called MAJESCOMASTEK
>
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Opinions expressed in this e-mail are those of the individual and not
> that of Mastek Limited, unless specifically indicated to that effect.
> Mastek Limited does not accept any responsibility or liability for it.
> This e-mail and attachments (if any) transmitted with it are
> confidential and/or privileged and solely for the use of the intended
> person or entity to which it is addressed. Any review,
> re-transmission, dissemination or other use of or taking of any action
> in reliance upon this information by persons or entities other than
> the intended recipient is prohibited. This e-mail and its attachments
> have been scanned for the presence of computer viruses. It is the
> responsibility of the recipient to run the virus check on e-mails and
> attachments before opening them. If you have received this e-mail in
> error, kindly delete this e-mail from desktop and server.
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
_______________________________________________
rules-users mailing list
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https://lists.jboss.org/mailman/listinfo/rules-users
3:46 a.m.
This is what I think is going on:when you call update($fact1) it will first
retract $fact1 which in turn retracts $fact2, the $fact1 is then inserted
again which cause another 'from' evaluation and a NEW $fact2 is pulled ->
no-loop doesn't work because Drools sees it as different data
I am just guessing here ...
On Fri, Feb 13, 2009 at 9:12 AM, Przemysław Różycki <P.Rozycki(a)amg.net.pl>wrote:
Hello,
Doesn't really anyone have any logical explanation of why such a rule
loops?
To remind the rule:
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
If I don't use 'from' everything is fine.
I really didn't find in a documentation, that 'from' causes any special
behaviour of the rule looping.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl
Przemysław Różycki pisze:
Thanks for answer, Vikrant, but I don't think so. I have always used
> no-loop without any additions and it worked (when I didn't use from). BTW,
> if you comment a condition with from, then the rule does not loop. I also
> checked with "no-loop true" and result is the same.
>
> Best regards,
> Przemek
>
> Vikrant Yagnick pisze:
>
>> I have to quickly recheck the documentation by I think you have to write
>> "no-loop true". Just writing no-loop defaults to false I guess.
>>
>> -----Original Message-----
>> From: rules-users-bounces(a)lists.jboss.org [mailto:
>> rules-users-bounces(a)lists.jboss.org] On Behalf Of Przemyslaw Rózycki
>> Sent: Tuesday, February 10, 2009 3:24 PM
>> To: Rules Users List
>> Subject: [rules-users] Rules with from always loops (Drools 4.0.7)
>>
>> Hello,
>>
>> why does such a rule always loop? Even if no-loop is used?
>>
>> rule "Hello World"
>> no-loop
>> when
>> $fact1 : MyFactBean1( )
>> $fact2 : MyFactBean2( ) from $fact1
>> then
>> System.out.println("Fired!!!");
>> update($fact1);
>> end
>>
>> The full code of my test application and drl is attached.
>>
>> Best regards,
>> --
>> Przemysław Różycki
>> AMG.net, A Bull Group Company
>> ul. Łąkowa 29
>> 90-554 Łódź
>> www.amg.net.pl
>>
>>
>> MASTEK LTD.
>> Mastek is in NASSCOM's 'India Top 20' Software Service Exporters
List.
>> In the US, we're called MAJESCOMASTEK
>>
>>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Opinions expressed in this e-mail are those of the individual and not
>> that of Mastek Limited, unless specifically indicated to that effect. Mastek
>> Limited does not accept any responsibility or liability for it. This e-mail
>> and attachments (if any) transmitted with it are confidential and/or
>> privileged and solely for the use of the intended person or entity to which
>> it is addressed. Any review, re-transmission, dissemination or other use of
>> or taking of any action in reliance upon this information by persons or
>> entities other than the intended recipient is prohibited. This e-mail and
>> its attachments have been scanned for the presence of computer viruses. It
>> is the responsibility of the recipient to run the virus check on e-mails and
>> attachments before opening them. If you have received this e-mail in error,
>> kindly delete this e-mail from desktop and server.
>>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>>
>>
>> _______________________________________________
>> 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
>
>
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
7:27 a.m.
Michal is correct. Every time a "from" expression is executed, Drools
does not know if a result for the expression is new or not and it creates a
new fact handle, bypassing the no-loop.
[]s
Edson
2009/2/13 Michal Bali <michalbali(a)gmail.com>
This is what I think is going on:when you call update($fact1) it
will
first retract $fact1 which in turn retracts $fact2, the $fact1 is then
inserted again which cause another 'from' evaluation and a NEW $fact2 is
pulled -> no-loop doesn't work because Drools sees it as different data
I am just guessing here ...
On Fri, Feb 13, 2009 at 9:12 AM, Przemysław Różycki <P.Rozycki(a)amg.net.pl>wrote:
> Hello,
>
> Doesn't really anyone have any logical explanation of why such a rule
> loops?
>
> To remind the rule:
>
> rule "Hello World"
> no-loop
> when
> $fact1 : MyFactBean1( )
> $fact2 : MyFactBean2( ) from $fact1
> then
> System.out.println("Fired!!!");
> update($fact1);
> end
>
> If I don't use 'from' everything is fine.
> I really didn't find in a documentation, that 'from' causes any special
> behaviour of the rule looping.
>
> Best regards,
> --
> Przemysław Różycki
> AMG.net, A Bull Group Company
> ul. Łąkowa 29
> 90-554 Łódź
> www.amg.net.pl
>
>
>
> Przemysław Różycki pisze:
>
> Thanks for answer, Vikrant, but I don't think so. I have always used
>> no-loop without any additions and it worked (when I didn't use from). BTW,
>> if you comment a condition with from, then the rule does not loop. I also
>> checked with "no-loop true" and result is the same.
>>
>> Best regards,
>> Przemek
>>
>> Vikrant Yagnick pisze:
>>
>>> I have to quickly recheck the documentation by I think you have to write
>>> "no-loop true". Just writing no-loop defaults to false I guess.
>>>
>>> -----Original Message-----
>>> From: rules-users-bounces(a)lists.jboss.org [mailto:
>>> rules-users-bounces(a)lists.jboss.org] On Behalf Of Przemyslaw Rózycki
>>> Sent: Tuesday, February 10, 2009 3:24 PM
>>> To: Rules Users List
>>> Subject: [rules-users] Rules with from always loops (Drools 4.0.7)
>>>
>>> Hello,
>>>
>>> why does such a rule always loop? Even if no-loop is used?
>>>
>>> rule "Hello World"
>>> no-loop
>>> when
>>> $fact1 : MyFactBean1( )
>>> $fact2 : MyFactBean2( ) from $fact1
>>> then
>>> System.out.println("Fired!!!");
>>> update($fact1);
>>> end
>>>
>>> The full code of my test application and drl is attached.
>>>
>>> Best regards,
>>> --
>>> Przemysław Różycki
>>> AMG.net, A Bull Group Company
>>> ul. Łąkowa 29
>>> 90-554 Łódź
>>> www.amg.net.pl
>>>
>>>
>>> MASTEK LTD.
>>> Mastek is in NASSCOM's 'India Top 20' Software Service Exporters
List.
>>> In the US, we're called MAJESCOMASTEK
>>>
>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> Opinions expressed in this e-mail are those of the individual and not
>>> that of Mastek Limited, unless specifically indicated to that effect. Mastek
>>> Limited does not accept any responsibility or liability for it. This e-mail
>>> and attachments (if any) transmitted with it are confidential and/or
>>> privileged and solely for the use of the intended person or entity to which
>>> it is addressed. Any review, re-transmission, dissemination or other use of
>>> or taking of any action in reliance upon this information by persons or
>>> entities other than the intended recipient is prohibited. This e-mail and
>>> its attachments have been scanned for the presence of computer viruses. It
>>> is the responsibility of the recipient to run the virus check on e-mails and
>>> attachments before opening them. If you have received this e-mail in error,
>>> kindly delete this e-mail from desktop and server.
>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>>
>>>
>>> _______________________________________________
>>> 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
>>
>>
>
> _______________________________________________
> 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
--
Edson Tirelli
JBoss Drools Core Development
JBoss, a division of Red Hat @ www.jboss.com
8:11 a.m.
Edson, Michal,
thank you for your answers. If I understand well, Drools can't recognize
if the $fact2 has been changed by the current rule or not.
Anyway, I found such a behaviur as a bit confusing, so my second
question is, is it a desirable behaviour? And is it going to be changed
or left as is?
Best regards
Przemyslaw
Edson Tirelli pisze:
Michal is correct. Every time a "from" expression is executed,
Drools does not know if a result for the expression is new or not and it
creates a new fact handle, bypassing the no-loop.
[]s
Edson
2009/2/13 Michal Bali <michalbali(a)gmail.com <mailto:michalbali@gmail.com>>
This is what I think is going on:
when you call update($fact1) it will first retract $fact1 which in
turn retracts $fact2, the $fact1 is then inserted again which cause
another 'from' evaluation and a NEW $fact2 is pulled -> no-loop
doesn't work because Drools sees it as different data
I am just guessing here ...
On Fri, Feb 13, 2009 at 9:12 AM, Przemysław Różycki
<P.Rozycki(a)amg.net.pl <mailto:P.Rozycki@amg.net.pl>> wrote:
Hello,
Doesn't really anyone have any logical explanation of why such a
rule loops?
To remind the rule:
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
If I don't use 'from' everything is fine.
I really didn't find in a documentation, that 'from' causes any
special behaviour of the rule looping.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl <http://www.amg.net.pl>
Przemysław Różycki pisze:
Thanks for answer, Vikrant, but I don't think so. I have
always used no-loop without any additions and it worked
(when I didn't use from). BTW, if you comment a condition
with from, then the rule does not loop. I also checked with
"no-loop true" and result is the same.
Best regards,
Przemek
Vikrant Yagnick pisze:
I have to quickly recheck the documentation by I think
you have to write "no-loop true". Just writing no-loop
defaults to false I guess.
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org
<mailto:rules-users-bounces@lists.jboss.org>
[mailto:rules-users-bounces@lists.jboss.org
<mailto:rules-users-bounces@lists.jboss.org>] On Behalf
Of Przemyslaw Rózycki
Sent: Tuesday, February 10, 2009 3:24 PM
To: Rules Users List
Subject: [rules-users] Rules with from always loops
(Drools 4.0.7)
Hello,
why does such a rule always loop? Even if no-loop is used?
rule "Hello World"
no-loop
when
$fact1 : MyFactBean1( )
$fact2 : MyFactBean2( ) from $fact1
then
System.out.println("Fired!!!");
update($fact1);
end
The full code of my test application and drl is attached.
Best regards,
--
Przemysław Różycki
AMG.net, A Bull Group Company
ul. Łąkowa 29
90-554 Łódź
www.amg.net.pl <http://www.amg.net.pl>
MASTEK LTD.
Mastek is in NASSCOM's 'India Top 20' Software Service
Exporters List.
In the US, we're called MAJESCOMASTEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Opinions expressed in this e-mail are those of the
individual and not that of Mastek Limited, unless
specifically indicated to that effect. Mastek Limited
does not accept any responsibility or liability for it.
This e-mail and attachments (if any) transmitted with it
are confidential and/or privileged and solely for the
use of the intended person or entity to which it is
addressed. Any review, re-transmission, dissemination or
other use of or taking of any action in reliance upon
this information by persons or entities other than the
intended recipient is prohibited. This e-mail and its
attachments have been scanned for the presence of
computer viruses. It is the responsibility of the
recipient to run the virus check on e-mails and
attachments before opening them. If you have received
this e-mail in error, kindly delete this e-mail from
desktop and server.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
<mailto:rules-users@lists.jboss.org>
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org <mailto:rules-users@lists.jboss.org>
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org <mailto:rules-users@lists.jboss.org>
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org <mailto:rules-users@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 <http://www.jboss.com>
------------------------------------------------------------------------
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
8:47 a.m.
Przemyslaw,
There are no plans to change the behavior for 5.0. In 5.1 with a feature
that we call "true modify" we may be able to improve the situation.
Let me explain it in a better way: the "from" expression is a black box
for the engine. You can call *any* code in that expression and a common case
is to use the expression to pull data from a database on-demand. Since it is
a black box, the engine assumes that every time the expression is
re-evaluated you are bringing new data into the engine and as so it creates
new fact handles for it. A modify in most Rete engines is a retract+assert
and it is like this in drools 4-5 too. So, when you modify the fact that is
written before the "from" in LHS, it will retract all facts previously
created by "from", re-evaluate it, and create new fact handles for them.
Since no-loop and lock-on-active use the fact handles to determine when a
fact is equals to another, you get this side effects.
A way to work around the problem is have your data in the working memory,
reducing the usage of from. Another way to work around the problem is if you
can write the patterns that use from before the patterns that are modified
by your rules. E.g:
Rule X
when
$a : A()
$b : B() from somewhere
$c : C()
$d : D()
then
// ...
end
If $a is modified by any rule or by the application, the whole LHS of the
above rule is re-evaluated. If $c is modified, only $c and $d are
reevaluated, and so on. Placing the facts that you modify frequently "after"
any pattern that uses "from" is a way to prevent this behavior. It is not
always possible, I know, but it helps with this side-effect whenever
possible.
[]s
Edson
2009/2/13 Przemysław Różycki <P.Rozycki(a)amg.net.pl>
Edson, Michal,
thank you for your answers. If I understand well, Drools can't recognize if
the $fact2 has been changed by the current rule or not.
Anyway, I found such a behaviur as a bit confusing, so my second question
is, is it a desirable behaviour? And is it going to be changed or left as
is?
Best regards
Przemyslaw
Edson Tirelli pisze:
>
> Michal is correct. Every time a "from" expression is executed, Drools
> does not know if a result for the expression is new or not and it creates a
> new fact handle, bypassing the no-loop.
>
> []s
> Edson
>
> 2009/2/13 Michal Bali <michalbali(a)gmail.com <mailto:michalbali@gmail.com
> >>
>
> This is what I think is going on:
> when you call update($fact1) it will first retract $fact1 which in
> turn retracts $fact2, the $fact1 is then inserted again which cause
> another 'from' evaluation and a NEW $fact2 is pulled -> no-loop
> doesn't work because Drools sees it as different data
> I am just guessing here ...
>
>
> On Fri, Feb 13, 2009 at 9:12 AM, Przemysław Różycki
> <P.Rozycki(a)amg.net.pl <mailto:P.Rozycki@amg.net.pl>> wrote:
>
> Hello,
>
> Doesn't really anyone have any logical explanation of why such a
> rule loops?
>
> To remind the rule:
>
>
> rule "Hello World"
> no-loop
> when
> $fact1 : MyFactBean1( )
> $fact2 : MyFactBean2( ) from $fact1
> then
> System.out.println("Fired!!!");
> update($fact1);
> end
>
> If I don't use 'from' everything is fine.
> I really didn't find in a documentation, that 'from' causes any
> special behaviour of the rule looping.
>
>
> Best regards,
> -- Przemysław Różycki
> AMG.net, A Bull Group Company
> ul. Łąkowa 29
> 90-554 Łódź
> www.amg.net.pl <http://www.amg.net.pl>
>
>
>
>
> Przemysław Różycki pisze:
>
> Thanks for answer, Vikrant, but I don't think so. I have
> always used no-loop without any additions and it worked
> (when I didn't use from). BTW, if you comment a condition
> with from, then the rule does not loop. I also checked with
> "no-loop true" and result is the same.
>
> Best regards,
> Przemek
>
> Vikrant Yagnick pisze:
>
> I have to quickly recheck the documentation by I think
> you have to write "no-loop true". Just writing no-loop
> defaults to false I guess.
>
> -----Original Message-----
> From: rules-users-bounces(a)lists.jboss.org
> <mailto:rules-users-bounces@lists.jboss.org>
> [mailto:rules-users-bounces@lists.jboss.org
> <mailto:rules-users-bounces@lists.jboss.org>] On Behalf
> Of Przemyslaw Rózycki
> Sent: Tuesday, February 10, 2009 3:24 PM
> To: Rules Users List
> Subject: [rules-users] Rules with from always loops
> (Drools 4.0.7)
>
> Hello,
>
> why does such a rule always loop? Even if no-loop is used?
>
> rule "Hello World"
> no-loop
> when
> $fact1 : MyFactBean1( )
> $fact2 : MyFactBean2( ) from $fact1
> then
> System.out.println("Fired!!!");
> update($fact1);
> end
>
> The full code of my test application and drl is attached.
>
> Best regards,
> -- Przemysław Różycki
> AMG.net, A Bull Group Company
> ul. Łąkowa 29
> 90-554 Łódź
> www.amg.net.pl <http://www.amg.net.pl>
>
>
> MASTEK LTD.
> Mastek is in NASSCOM's 'India Top 20' Software Service
> Exporters List.
> In the US, we're called MAJESCOMASTEK
>
>
>
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>
> --
> Edson Tirelli
> JBoss Drools Core Development
> JBoss, a division of Red Hat @ www.jboss.com <http://www.jboss.com>
>
>
> ------------------------------------------------------------------------
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Edson Tirelli
JBoss Drools Core Development
JBoss, a division of Red Hat @ www.jboss.com
5769
days inactive
5772
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7 comments
4 participants
participants (4)
-
Edson Tirelli -
Michal Bali -
Przemysław Różycki -
Vikrant Yagnick