from:"bdolbeare"

[rules-users] ClassCastException due to binding

2013-06-04 Thread bdolbeare

We have a need to support binds for conditional or elements so that we can
describe why a rule fired in the then clause of a rule.  The following DRL
is a simple example of what we are trying to do.  There are two versions of
our rule in the DRL:

*rule WORKING:  find with or*:  works but only because the first variable
we try to bind in the or expression is of type target which is a super
class of the other elements in the or expression.  

*rule BROKEN:  find with or*:  causes a class cast exception when the
bar pattern is matched because the then clause tries to store the bar
object in handle x which it thinks is of type foo.  

Is there a way to define the object type for the bind variable?  

Is there any other way to make something like this work?
 


package tests

import org.apache.log4j.Logger;

global Logger log

declare target
notreal : boolean 
end

declare foo extends target
foovalue : String
end

declare bar extends target
barvalue : String
end  

rule insertdata
when
then
insert(new foo(false, a));
insert(new bar(false, b));
end

rule WORKING:  find with or
when
( or x: target(notreal) 
x: foo(foovalue == a) 
x: bar(barvalue == b)
)
then
log.info(i found object:  + x);
end

rule BROKEN:  find with or
when
( or
x: foo(foovalue == a) 
x: bar(barvalue == b)
)
then
log.info(i found object:  + x);
end



Exception executing consequence for rule find with or in tests:
java.lang.ClassCastException: tests.bar cannot be cast to tests.foo
at
org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
at 
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1283)
at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1209)
at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1442)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674)
at
org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230)
at
org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:278)
at tests.DroolsTest.testStateless(DroolsTest.java:120)
at tests.DroolsTest.runTest(DroolsTest.java:74)
at tests.DroolsTest.main(DroolsTest.java:59)
Caused by: java.lang.ClassCastException: tests.bar cannot be cast to
tests.foo
at
tests.Rule_find_with_or_411ee1c99de54340945b2b707ad0a576DefaultConsequenceInvoker.evaluate(Unknown
Source)
at 
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1273)
... 9 more



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[rules-users] Finding matching values in composite constraint

2013-01-05 Thread bdolbeare

Is there a way to determine (in the rule consequence) which condition in a
composite constraint caused a rule to succeed?  

I am working on a system that allows users to create rules via a custom UI
and when one of their rules fires, I want to be able to create a message
that describes why their rule fired.  In a real example, they might have a
list of a few hundred conditions in a composite constraint.  

An example rule with just two conditions in a composite constraint follows:  

rule test rule
when
MyObject( (myfield  str[startsWith] a || myfield str[startsWith] b) ) 
then
System.out.prinltn(kcontext.getRule().getName() +  fired because myfield
started with ???);
end

Is this exposed somewhere in the variables like kcontext that are available
to each rule in their consequence?



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Re: [rules-users] Finding matching values in composite constraint

2013-01-05 Thread bdolbeare

Suppose we have a Transaction object with a String field.  Users want to
create a rule through our application that says alert me whenever the value
of that field contains a value in a list of values provided in the rule. 
It's easy enough to write this type of rule and send an alert; however, it
would be helpful to include the value from the list that matched.  

The only way I can think to do this type of thing is to create a function
somewhere that checks if the field contains any of the values in the user
list and if so return that value.  Then call that function in the rule
condition and bind the result.  Something like what follows:


public class ExternalMatcher
{
  public static String contains(String field, String...list)
  {
  // return the first string that satisfies the contains logic or null if no
strings succeed
  }
}

rule test
when 
Transaction( $matchedValue : ExternalMatcher.contains(field, value1,
value2, value3) != null)
then
sendAlert(I found a transaction that matched your criteria because field
foo equals:  + $matchedValue);
end





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[rules-users] Drools Rule Evaluations are Inconsistent

2012-09-22 Thread bdolbeare

Drools is not producing consistent results in the following example.  If you
run the DRL shown below, you will see that rules 2 and 3 activate and log a
message.  If you then comment out rule 3 in the DRL (you must put the entire
rule inside /*  */ characters rather than simply disabling it), and rerun
it, you'll notice that rules 1 and 2 fire.  How is it that the presence of
rule 3 affects whether or not rule 1 activates?  These two rules are not
dependent in their DRL.

It appears to be related to the fact that rule 1 uses single quotes instead
of double quotes.  If you change that, then Drools starts behaving
consistently.  This makes me believe that the problem is somehow related to
how Drools is building the Rete tree with the single quotes.



With all three rules active I get:

[main]::INFO ::DroolsTest::test 3 hit on RecordA( id=100 ) - RecordB(
id=100, role=2 )
[main]::INFO ::DroolsTest::test 2 hit on RecordA( id=100 ) - RecordB(
id=100, role=1 )


With rule 3 commented out I get:

[main]::INFO ::DroolsTest::test 2 hit on RecordA( id=100 ) - RecordB(
id=100, role=1 )
[main]::INFO ::DroolsTest::test 1 hit on RecordA( id=100 ) - RecordB(
id=100, role=1 )


Interestingly, if you comment out rule 2 so only rules 1 and 3 are active,
rule 1 fires again:

[main]::INFO ::DroolsTest::test 3 hit on RecordA( id=100 ) - RecordB(
id=100, role=2 )
[main]::INFO ::DroolsTest::test 1 hit on RecordA( id=100 ) - RecordB(
id=100, role=1 )



*Environment:  Drools 5.4.0*




package tests

import org.apache.log4j.Logger;

global Logger log


declare RecordA
id : long
end

declare RecordB
id : long
role : String
end

rule insert data 1
salience 9
when
then
insert (new RecordA(100));
insert (new RecordB(100, 1));
insert (new RecordB(100, 2));
end

rule test 1
when
a : RecordA( )
b : RecordB( id == b.id, role == '1' )
then
log.info(String.format(%s hit on %s - %s, 
kcontext.getRule().getName(),
a, b));
end

rule test 2
when
a : RecordA( )
b : RecordB( id == b.id, role == 1 )
then
log.info(String.format(%s hit on %s - %s, 
kcontext.getRule().getName(),
a, b)); 
end

rule test 3
when
a : RecordA( )
b : RecordB( id == b.id, role == 2 )
then
log.info(String.format(%s hit on %s - %s, 
kcontext.getRule().getName(),
a, b));
end






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Re: [rules-users] Drools Rule Evaluations are Inconsistent

2012-09-22 Thread bdolbeare

I was able to use the Drools Eclipse Plugin to view the Rete tree and I can
confirm that it Drools does build the tree differently under the scenarios
described above.  With rule 3 commented out, there are 2 AlphaNodes -- one
checks for [role==1] and the other checks for [role=='1'].  With rule 3
uncommented, the AlphaNode for [role=='1'] disappears.  It seems rather
scary that Drools doesn't create the Rete tree the same way.  I hope there
aren't any other issues like this that may affect the validity of the
rules???

Do you recommend skipping the upgrade to Drools 5.4.0 in favor of another
version?



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[rules-users] Bug in enabled rule attribute???

2012-08-07 Thread bdolbeare

The following DRL produces a Null Pointer Exception when the enabled
attribute is set to false on test rule 2.  Any ideas why?  Changing this
value to true or commenting out the rule causes things to succeed.

Environment:  Java 7 and Drools 5.4


package tests

import org.apache.log4j.Logger;

import java.util.List;

global Logger log

declare Data
name : String
end

rule insert Data
when
then
insert(new Data(test));
end

rule test rule 2
enabled false
when
d : List() from collect (Data( name == test) )
then
log.info(String.format(%s hit on %s, 
kcontext.getRule().getName(), d)); 
end



Exception executing consequence for rule insert Data in tests:
java.lang.NullPointerException
at
org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
at 
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1283)
at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1209)
at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1442)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674)
at
org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230)
at
org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:278)
at tests.DroolsTest.testStateless(DroolsTest.java:98)
at tests.DroolsTest.runTest(DroolsTest.java:60)
at tests.DroolsTest.main(DroolsTest.java:45)
Caused by: java.lang.NullPointerException
at 
org.drools.common.DefaultAgenda.createActivation(DefaultAgenda.java:569)
at
org.drools.reteoo.RuleTerminalNode.modifyLeftTuple(RuleTerminalNode.java:297)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateModifyChildLeftTuple(SingleLeftTupleSinkAdapter.java:259)
at
org.drools.reteoo.AccumulateNode.evaluateResultConstraints(AccumulateNode.java:676)
at
org.drools.reteoo.ReteooWorkingMemory$EvaluateResultConstraints.execute(ReteooWorkingMemory.java:591)
at
org.drools.common.PropagationContextImpl.evaluateActionQueue(PropagationContextImpl.java:345)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:342)
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:298)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:888)
at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:187)
at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:181)
at
tests.Rule_insert_Data_2eb7a40b15e640d6bc777e1075d1218b.defaultConsequence(Rule_insert_Data_2eb7a40b15e640d6bc777e1075d1218b.java:7)
at
tests.Rule_insert_Data_2eb7a40b15e640d6bc777e1075d1218bDefaultConsequenceInvokerGenerated.evaluate(Unknown
Source)
at
tests.Rule_insert_Data_2eb7a40b15e640d6bc777e1075d1218bDefaultConsequenceInvoker.evaluate(Unknown
Source)
at 
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1273)



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Re: [rules-users] Unification with logical or question

2012-06-09 Thread bdolbeare

Thank you for your response. 

I am aware that the rule with the conditional or gets rewritten into two
separate rules and that rule is actually doing what I would expect --
producing two matches.

The main part of my question is why doesn't the second rule produce the same
results -- I was expecting two matches but it only produces one.  The only
thing I can think of is that it's an order of operations issue but that
doesn't seem to make sense given the parenthesis.  The second pattern in
that rule is basically:

 condition || (! condition  unification)

This should produce two matches with the given data but, it doesn't produce
a match when the condition left of the || is satisfied (in that case the
unification shouldn't be happening but, maybe it is?).  If I change the rule
to the following, it does produce two matches which makes me believe that
the unification is affecting things.

 condition || ! condition

Thoughts?


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Re: [rules-users] Newbie problem: I can't get Eclipse and Examples working

2012-06-09 Thread bdolbeare

Does your CLASSPATH  for the runtime configuration include the target/classes
directory?

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[rules-users] Unification with logical or question

2012-06-08 Thread bdolbeare

Can someone explain to me why these two rules behave differently?  I expected
that the second rule would produce the same output as the first but it seems
to ignore the first half of the logical or expression.  Is this because the
unification happens before the null checks occur?



declare Foo
name : String
item : Item
end
declare Item
id : long
end

rule insert stuff
when
then
Item item1 = new Item(1);

Foo foo1 = new Foo(foo1, item1);
insert(foo1);

Foo foo3 = new Foo(foo3, null);
insert(foo3);
end
rule Unification Test Rule
when
f : Foo ( item != null, $item := item ) 
f2 : (
Foo ( item == null ) 
or Foo ( $item := item ) 
)
then
System.out.println(String.format(%s Fired:\n\tFoo: %s\n\t%s,
kcontext.getRule().getName(), f, f2));
end
rule Unification Test Rule 2
salience -10
when
f : Foo ( item != null, $item := item ) 
f2 : Foo ( ( item == null ) || ( item != null  $item := item 
) )
then
System.out.println(String.format(%s Fired:\n\tFoo: %s\n\t%s,
kcontext.getRule().getName(), f, f2));
end


Unification Test Rule Fired:
Foo: Foo( name=foo1, item=Item( id=1 ) )
Foo( name=foo3, item=null )
Unification Test Rule Fired:
Foo: Foo( name=foo1, item=Item( id=1 ) )
Foo( name=foo1, item=Item( id=1 ) )

Unification Test Rule 2 Fired:
Foo: Foo( name=foo1, item=Item( id=1 ) )
Foo( name=foo1, item=Item( id=1 ) )

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[rules-users] Integrating Drools with rules from a legacy BRMS

2012-05-29 Thread bdolbeare

I am working on integrating Drools with a legacy BRMS that was developed
in-house. The customers like the BRMS and are unwilling to migrate to
another tool such as Guvnor. The BRMS creates the rules in a proprietary
XML format. In order to integrate Drools with the BRMS, I need to convert
these rules to a format that Drools understands and that leaves me with what
seems like 3 options:

1) Write some XSLT to transform the proprietary XML to Drools XML format.
This seems straightforward; however, I am concerned that the online
documentation states that the Drools XML format should be considered
deprecated. I'd hate to invest much time in this approach if the XML support
is going to disappear in a future release.

2) Write my own parser that can convert the proprietary XML to classes in
the org.lang.descr package. I'm not sure if the Drools developers intend for
others to use these classes directly. For instance, if they change
frequently, this approach may be difficult to maintain.

3) Write my own parser that can convert the proprietary XML to DRL. This
approach seems unfortunate in that the rules would be parsed twice; first to
convert them to DRL and then internally by the Drools DrlParser. Also, this
doesn't seem to offer any benefit over approach 2 (except that I know DRL
well and wouldn't have to learn how the org.lang.descr classes work [not
much documentation in those classes]).

Right now, I'm leaning towards approach 2. Any thoughts or suggestions
would be appreciated.

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