1:22 p.m.
I have a dummy program that asserts 2 simple facts into working memory, then
reads a simple rule file into the rule base, then fires the rules. I've
attached the rules and the NullPointerException that results.
However, if I read the rules first then assert the facts, the program runs
fine.
Alternatively, if I modify the second rule such that the modify occurs
before the retract, the program runs fine even if I assert the facts first
then read the rules.
In general, I may not be able to control when facts are asserted vs. when
rules are read in. Should this be a problem?
Any hints greatly appreciated!!
Thanks,
Justine
simple.drl:
rule "setupFactC"
no-loop true
when
a: factA(s:field1, i:field2, f:field3)
not c : factC(f1==s)
then
assert(s != null ? new factC(s, i, f) :
new factC());
end
rule "factBWithRetract"
no-loop true
when
b : factB(s:f1, i:f2, f:f3)
a : factA(field1==s)
c : factC(f1==s)
then
c.setF3(f);
retract(b);
modify(c);
end
Stack trace:
java.lang.NullPointerException
at org.drools.base.com.vsasset.rules.isolate.factB$getF1.getValue(Unknown
Source)
at org.drools.base.ClassFieldExtractor.getValue(Unknown Source)
at org.drools.rule.Declaration.getValue(Unknown Source)
at org.drools.rule.BoundVariableConstraint.isAllowed(Unknown Source)
at org.drools.common.BetaNodeBinder.isAllowed(Unknown Source)
at org.drools.reteoo.JoinNode.modifyObject(Unknown Source)
at org.drools.reteoo.ObjectSource.propagateModifyObject(Unknown Source)
at org.drools.reteoo.ObjectTypeNode.modifyObject(Unknown Source)
at org.drools.reteoo.Rete.modifyObject(Unknown Source)
at org.drools.reteoo.ReteooRuleBase.modifyObject(Unknown Source)
at org.drools.reteoo.ReteooWorkingMemory.modifyObject(Unknown Source)
at org.drools.base.DefaultKnowledgeHelper.modifyObject(Unknown Source)
at com.vsasset.rules.isolate.Rule_factBWithRetract_0.consequence
(Rule_factBWithRetract_0.java:10)
at
com.vsasset.rules.isolate.Rule_factBWithRetract_0ConsequenceInvoker.evaluate
(Rule_factBWithRetract_0ConsequenceInvoker.java:26)
at org.drools.common.DefaultAgenda.fireActivation(Unknown Source)
at org.drools.common.DefaultAgenda.fireNextItem(Unknown Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
at org.drools.common.AbstractRuleBase.addPackage(Unknown Source)
at com.vsasset.rules.isolate.TestCase.main(TestCase.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(
NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(
DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
Exception in thread "main" org.drools.spi.ConsequenceException:
java.lang.NullPointerException
at org.drools.common.DefaultAgenda.fireActivation(Unknown Source)
at org.drools.common.DefaultAgenda.fireNextItem(Unknown Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown Source)
at org.drools.common.AbstractRuleBase.addPackage(Unknown Source)
at com.vsasset.rules.isolate.TestCase.main(TestCase.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(
NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(
DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
2:42 p.m.
Hey Justine,
You found a nice scenario! Seems a bug to me.
Would you like to please open a JIRA for that attaching your test
code and your comments? This way you can follow the resolution of the
problem. I will investigate that.
BTW, what version are you using?
Thank you,
Edson
Justine Hlista wrote:
I have a dummy program that asserts 2 simple facts into working
memory, then reads a simple rule file into the rule base, then fires
the rules. I've attached the rules and the NullPointerException that
results.
However, if I read the rules first then assert the facts, the program
runs fine.
Alternatively, if I modify the second rule such that the modify occurs
before the retract, the program runs fine even if I assert the facts
first then read the rules.
In general, I may not be able to control when facts are asserted vs.
when rules are read in. Should this be a problem?
Any hints greatly appreciated!!
Thanks,
Justine
simple.drl:
rule "setupFactC"
no-loop true
when
a: factA(s:field1, i:field2, f:field3)
not c : factC(f1==s)
then
assert(s != null ? new factC(s, i, f) :
new factC());
end
rule "factBWithRetract"
no-loop true
when
b : factB(s:f1, i:f2, f:f3)
a : factA(field1==s)
c : factC(f1==s)
then
c.setF3(f);
retract(b);
modify(c);
end
Stack trace:
java.lang.NullPointerException
at
org.drools.base.com.vsasset.rules.isolate.factB$getF1.getValue(Unknown
Source)
at org.drools.base.ClassFieldExtractor.getValue (Unknown Source)
at org.drools.rule.Declaration.getValue(Unknown Source)
at org.drools.rule.BoundVariableConstraint.isAllowed(Unknown Source)
at org.drools.common.BetaNodeBinder.isAllowed(Unknown Source)
at org.drools.reteoo.JoinNode.modifyObject(Unknown Source)
at org.drools.reteoo.ObjectSource.propagateModifyObject(Unknown
Source)
at org.drools.reteoo.ObjectTypeNode.modifyObject(Unknown Source)
at org.drools.reteoo.Rete.modifyObject(Unknown Source)
at org.drools.reteoo.ReteooRuleBase.modifyObject(Unknown Source)
at org.drools.reteoo.ReteooWorkingMemory.modifyObject(Unknown Source)
at org.drools.base.DefaultKnowledgeHelper.modifyObject (Unknown
Source)
at
com.vsasset.rules.isolate.Rule_factBWithRetract_0.consequence(Rule_factBWithRetract_0.java:10)
at
com.vsasset.rules.isolate.Rule_factBWithRetract_0ConsequenceInvoker.evaluate(Rule_factBWithRetract_0ConsequenceInvoker.java:26)
at org.drools.common.DefaultAgenda.fireActivation(Unknown Source)
at org.drools.common.DefaultAgenda.fireNextItem(Unknown Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown
Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown
Source)
at org.drools.common.AbstractRuleBase.addPackage(Unknown Source)
at com.vsasset.rules.isolate.TestCase.main(TestCase.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java
:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
Exception in thread "main" org.drools.spi.ConsequenceException:
java.lang.NullPointerException
at org.drools.common.DefaultAgenda.fireActivation(Unknown Source)
at org.drools.common.DefaultAgenda.fireNextItem(Unknown Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown
Source)
at org.drools.common.AbstractWorkingMemory.fireAllRules(Unknown
Source)
at org.drools.common.AbstractRuleBase.addPackage(Unknown Source)
at com.vsasset.rules.isolate.TestCase.main(TestCase.java:36)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java
:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:90)
------------------------------------------------------------------------
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
--
Edson Tirelli
Software Engineer - JBoss Rules Core Developer
Office: +55 11 3124-6000
Mobile: +55 11 9218-4151
JBoss, a division of Red Hat @ www.jboss.com
2:24 p.m.
Thanks for the quick reply! I am using 3.0.5. I'm trying to stick with the
"officially released" version (off the JBoss site) until I have a little
more experience with drools (since most of my problems will undoubtedly be
caused by me for a while).
I will open a JIRA issue with my stuff atttached now.
Thanks,
Justine
On 1/18/07, Edson Tirelli <tirelli(a)post.com> wrote:
Hey Justine,
You found a nice scenario! Seems a bug to me.
Would you like to please open a JIRA for that attaching your test
code and your comments? This way you can follow the resolution of the
problem. I will investigate that.
BTW, what version are you using?
3:38 p.m.
Sure, 3.0.5 is the latest stable release.
Thank you,
Edson
Justine Hlista wrote:
Thanks for the quick reply! I am using 3.0.5. I'm trying to stick
with
the "officially released" version (off the JBoss site) until I have a
little more experience with drools (since most of my problems will
undoubtedly be caused by me for a while).
I will open a JIRA issue with my stuff atttached now.
Thanks,
Justine
On 1/18/07, *Edson Tirelli* < tirelli(a)post.com
<mailto:tirelli@post.com>> wrote:
Hey Justine,
You found a nice scenario! Seems a bug to me.
Would you like to please open a JIRA for that attaching your test
code and your comments? This way you can follow the resolution of the
problem. I will investigate that.
BTW, what version are you using?
------------------------------------------------------------------------
_______________________________________________
rules-users mailing list
rules-users(a)lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users
--
Edson Tirelli
Software Engineer - JBoss Rules Core Developer
Office: +55 11 3124-6000
Mobile: +55 11 9218-4151
JBoss, a division of Red Hat @ www.jboss.com
2:18 p.m.
Here is a simpler example where the behavior differs depending on whether
you assert the fact first or load the rules first. This is just a simple
fact class with a string variable called field1. I create and assert the
fact with the string "hello" for field1, then I load the following rule
file:
package com.vsasset.rules.isolate;
import java.lang.String;
rule "simpleDependence"
no-loop true
when
a: factA(field1=="hello")
then
a.setField1("world");
modify(a);
System.out.println("a: " + a.getField1());
TestCase.fireRules();
end
rule "simpleRetract"
no-loop true
when
a: factA(field1 == "world")
then
retract(a);
System.out.println("Retracted a");
end
The second rule (simpleRetract) does not print when the initial factA is
asserted before the rules are loaded. If the rules are loaded first, then
the second rule prints.
To be honest, I'm not sure whether to expect the second rule to print --
does it get immediately de-activated upon the retract so that any further
statements are not executed?
In any event, I would expect the behavior to be the same whether I assert
factA first or load the rules first.
Am I missing something fundamental? Perhaps I am mis-using the API...
Thanks,
Justine
6551
days inactive
6552
days old
4 comments
2 participants
participants (2)
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Edson Tirelli -
Justine Hlista