1:36 p.m.
My colleague has confirmed that this behavior has been around since Drools 4, and it
continues to be a problem for Drools 5.0.1 and 5.1.0.M1, assuming it's a problem and
not working as intended.
$fact.setPath("...") implements the correct PropertyChangeSupport mechanism for
Drools. At least Drools is using it and responding mostly as expected.
This runs once:
rule "Constrain to owner or published to public"
when
$fact : ListFact(
$path : path not matches ".*owner.*",
noopResponse == true
)
$model : Model()
then
modify($fact)
{
setPath($fact.getPath() + "[owner]")
}
update($fact);
end
This runs twice:
rule "Constrain to owner or published to public"
when
$fact : ListFact(
$path : path not matches ".*owner.*",
noopResponse == true
)
$model : Model()
then
modify($fact)
{
setPath($fact.getPath() + "[owner]")
}
end
If I don't use modify(...) and simply change the $fact bean path property, the same
thing occurs. If I explicitly call update($fact), the rule runs once. If I don't it
runs twice.
I get "/path[owner][owner]" when I actually wanted "/path[owner]",
because it ran twice, not once.
Why doe update(...) work differently from the PropertyChangeSupport mechanism???
Shouldn't I be able to depend on Drools to run this rule only one time?
I am, admittedly, a bit of a noob at this, but I ran this by my local Drools resident
expert, and he doesn't know the answer either.
Thanks so much!
Jason Smith
Software Engineer
InfoTrust Group, Inc.
500 Discovery Parkway, Suite 200
Superior, CO 80027
Office 303-627-6571
Fax 303-666-6711
Email jsmith@infotrustgroup.com<mailto:jsmith@infotrustgroup.com>
WEB www.infotrustgroup.com<http://www.infotrustgroup.com/>
This e-mail and all information included herein do not constitute a legal agreement
accorded by INFOTRUST GROUP and its affiliates and subsidiaries. All legal agreements
must be formulated in writing by a legal representative of INFOTRUST GROUP. This email and
any files transmitted with it are confidential and intended solely for the use of the
individual or entity to whom they are addressed. If you have received this e-mail by
mistake, please inform us and destroy this e-mail and any documents it might contain.
Please note that any views or opinions presented in this email are solely those of the
author and do not necessarily represent those of the company. Finally, the recipient
should check this email and any attachments for the presence of viruses. The company
accepts no liability for any damage caused by any virus transmitted by this email. Thank
you for your cooperation.
1:39 p.m.
New subject: FW: Rule runs twice without explicit call to update($fact).
I never got an answer, any answer to this question. I really need to know if
PropertyChangeSupport actually works. Is anyone out there successfully using it?
In one case (using "modify()") I get a NPE. In all cases, the rules run twice
unless I explicitly call "update()". Is anyone *not* seeing this behaviour? Is
anyone successfully using the PropertyChangeSupport mechanism without explicit calls to
"update()"???
Jason Smith
________________________________
From: Jason Smith
Sent: Monday, November 23, 2009 12:36 PM
To: rules-users(a)lists.jboss.org
Subject: Rule runs twice without explicit call to update($fact).
My colleague has confirmed that this behavior has been around since Drools 4, and it
continues to be a problem for Drools 5.0.1 and 5.1.0.M1, assuming it's a problem and
not working as intended.
$fact.setPath("...") implements the correct PropertyChangeSupport mechanism for
Drools. At least Drools is using it and responding mostly as expected.
This runs once:
rule "Constrain to owner or published to public"
when
$fact : ListFact(
$path : path not matches ".*owner.*",
noopResponse == true
)
$model : Model()
then
modify($fact)
{
setPath($fact.getPath() + "[owner]")
}
update($fact);
end
This runs twice:
rule "Constrain to owner or published to public"
when
$fact : ListFact(
$path : path not matches ".*owner.*",
noopResponse == true
)
$model : Model()
then
modify($fact)
{
setPath($fact.getPath() + "[owner]")
}
end
If I don't use modify(...) and simply change the $fact bean path property, the same
thing occurs. If I explicitly call update($fact), the rule runs once. If I don't it
runs twice.
I get "/path[owner][owner]" when I actually wanted "/path[owner]",
because it ran twice, not once.
Why doe update(...) work differently from the PropertyChangeSupport mechanism???
Shouldn't I be able to depend on Drools to run this rule only one time?
I am, admittedly, a bit of a noob at this, but I ran this by my local Drools resident
expert, and he doesn't know the answer either.
Thanks so much!
Jason Smith
Software Engineer
InfoTrust Group, Inc.
500 Discovery Parkway, Suite 200
Superior, CO 80027
Office 303-627-6571
Fax 303-666-6711
Email jsmith@infotrustgroup.com<mailto:jsmith@infotrustgroup.com>
WEB www.infotrustgroup.com<http://www.infotrustgroup.com/>
This e-mail and all information included herein do not constitute a legal agreement
accorded by INFOTRUST GROUP and its affiliates and subsidiaries. All legal agreements
must be formulated in writing by a legal representative of INFOTRUST GROUP. This email and
any files transmitted with it are confidential and intended solely for the use of the
individual or entity to whom they are addressed. If you have received this e-mail by
mistake, please inform us and destroy this e-mail and any documents it might contain.
Please note that any views or opinions presented in this email are solely those of the
author and do not necessarily represent those of the company. Finally, the recipient
should check this email and any attachments for the presence of viruses. The company
accepts no liability for any damage caused by any virus transmitted by this email. Thank
you for your cooperation.
1:51 a.m.
New subject: FW: Rule runs twice without explicit call to update($fact).
"Just the place for a Snark! I have said it twice:
That alone should encourage the crew.
Just the place for a Snark! I have said it thrice:
What i tell you three times is true."
[...]
He had forty-two boxes, all carefully packed,
With his name painted clearly on each:
But, since he omitted to mention the fact, (!)
They were all left behind on the beach.
I'm not sure whether Lewis Carroll had Drools in mind when he wrote these lines,
but the allusions are there. ;-)
That said, I'll now turn to your code which indeed achieves to
"tell it thrice": once by calling the setter in a modify, twice by
calling update,
and the third time by using the PropertyChangeSupport. Small wonder that
the engine is a little confused. Simply use just one of the three, and all will
be fine.
You should certainly do it once, or else the fact will be left changed but
forgotten on the beach...
-W
2009/11/25 Jason Smith <jsmith(a)infotrustgroup.com>:
I never got an answer, any answer to this question. I really need to
know
if PropertyChangeSupport actually works. Is anyone out there successfully
using it?
In one case (using "modify()") I get a NPE. In all cases, the rules run
twice unless I explicitly call "update()". Is anyone *not* seeing this
behaviour? Is anyone successfully using the PropertyChangeSupport mechanism
without explicit calls to "update()"???
Jason Smith
________________________________
From: Jason Smith
Sent: Monday, November 23, 2009 12:36 PM
To: rules-users(a)lists.jboss.org
Subject: Rule runs twice without explicit call to update($fact).
My colleague has confirmed that this behavior has been around since Drools
4, and it continues to be a problem for Drools 5.0.1 and 5.1.0.M1, assuming
it's a problem and not working as intended.
$fact.setPath("...") implements the correct PropertyChangeSupport mechanism
for Drools. At least Drools is using it and responding mostly as expected.
This runs once:
rule
"Constrain to owner or published to public"
when
$fact : ListFact(
$path : path
not matches ".*owner.*",
noopResponse ==
true
)
$model : Model()
then
modify($fact)
{
setPath($fact.getPath() +
"[owner]")
}
update($fact);
end
This runs twice:
rule
"Constrain to owner or published to public"
when
$fact : ListFact(
$path : path
not matches ".*owner.*",
noopResponse ==
true
)
$model : Model()
then
modify($fact)
{
setPath($fact.getPath() + "[owner]")
}
end
If I don't use modify(...) and simply change the $fact bean path property,
the same thing occurs. If I explicitly call update($fact), the rule runs
once. If I don't it runs twice.
I get "/path[owner][owner]" when I actually wanted "/path[owner]",
because
it ran twice, not once.
Why doe update(...) work differently from the PropertyChangeSupport
mechanism??? Shouldn't I be able to depend on Drools to run this rule only
one time?
I am, admittedly, a bit of a noob at this, but I ran this by my local Drools
resident expert, and he doesn't know the answer either.
Thanks so much!
Jason Smith
Software Engineer
InfoTrust Group, Inc.
500 Discovery Parkway, Suite 200
Superior, CO 80027
Office 303-627-6571
Fax 303-666-6711
Email jsmith(a)infotrustgroup.com
WEB www.infotrustgroup.com
This e-mail and all information included herein do not constitute a legal
agreement accorded by INFOTRUST GROUP and its affiliates and subsidiaries.
All legal agreements must be formulated in writing by a legal representative
of INFOTRUST GROUP. This email and any files transmitted with it are
confidential and intended solely for the use of the individual or entity to
whom they are addressed. If you have received this e-mail by mistake,
please inform us and destroy this e-mail and any documents it might
contain. Please note that any views or opinions presented in this email are
solely those of the author and do not necessarily represent those of the
company. Finally, the recipient should check this email and any attachments
for the presence of viruses. The company accepts no liability for any damage
caused by any virus transmitted by this email. Thank you for your
cooperation.
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Wolfgang Laun