6:54 a.m.
Hi
I'm currently trying to create a simple example in converting a DRL rule
into an XML rule and compiling that but it seems that the XML conversion is
not working correctly or have I done something wrong? Has anyone noticed
this problem too?
public static String convertDrlToXmlRule(String drlRule) throws
DroolsParserException
{
DrlParser parser = new DrlParser();
PackageDescr descr = parser.parse(drlRule);
// Dump to xml rule.
XmlDumper dumper = new XmlDumper();
return dumper.dump(descr);
}
the code above converts a drlRule and dumps out an XML format.
My example drl rule (this compiles fine):
public static String exampleRule = "package com.rules;" +
"import com.rules.my.test.Message;" +
"import com.rules.my.test.SubMessage;" +
"import com.rules.my.test.SubSubMessage;" +
"rule \"exampleRule\"" +
" dialect \"mvel\"" +
" when" +
" Message( $subMessage :
subMessage)\n" +
" SubMessage( $subSubMessage :
subSubMessage) from $subMessage\n" +
" SubSubMessage( message ==
\"SubSub\") from $subSubMessage\n" +
" \nthen\n" +
" System.out.println( $subMessage );"
+
" end";
What comes out:
<?xml version="1.0" encoding="UTF-8"?>
<package name="com.rules"
xmlns="http://drools.org/drools-4.0"
xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
xs:schemaLocation="http://drools.org/drools-4.0 drools-4.0.xsd">
<import name="com.rules.my.test.Message" />
<import name="com.rules.my.test.SubMessage" />
<import name="com.rules.my.test.SubSubMessage" />
<rule name="exampleRule ">
<rule-attribute name="dialect" value="mvel" />
<lhs>
<pattern object-type="Message" >
<field-binding field-name="subMessage"
identifier="$subMessage" />
</pattern>
<pattern object-type="SubMessage" >
<field-binding field-name="subSubMessage"
identifier="$subSubMessage" />
<field-binding field-name="subSubMessage"
identifier="$subSubMessage" />
<from>
<expression> $subMessage </expression>
</from>
</pattern>
<pattern object-type="SubSubMessage" >
<field-constraint field-name="message">
<literal-restriction evaluator="==" value="SubSub"
/>
</field-constraint>
<field-constraint field-name="message">
<literal-restriction evaluator="==" value="SubSub"
/>
</field-constraint>
<from>
<expression> $subSubMessage </expression>
</from>
</pattern>
</lhs>
<rhs>
System.out.println( $subMessage );
</rhs>
</rule>
</package>
If you noticed above it comes out with duplicate field-constaints for
pattern SubSubMessage?? However, thats not a big problem, when I try to
compile the rule in XML format it throws:
org.xml.sax.SAXParseException: <from> is after an invalid element:
org.drools.xml.Handler
at org.drools.xml.XmlPackageReader.validate(XmlPackageReader.java:506)
at
org.drools.xml.XmlPackageReader.startElement(XmlPackageReader.java:394)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown
Source)
at org.apache.xerces.impl.xs.XMLSchemaValidator.startElement(Unknown
Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown
Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown
Source)
at org.apache.xerces.jaxp.SAXParserImpl.parse(Unknown Source)
at org.drools.xml.XmlPackageReader.read(XmlPackageReader.java:321)
at org.drools.xml.XmlPackageReader.read(XmlPackageReader.java:247)
Any suggestions in what I am doing wrong?
Cheers,
Le.
8:24 a.m.
New subject: Sporadic error running drools
Are you using Drools 4.0.7 with MVEL 1.3.1?
If yes, can you please open a jira for this error stating if your program
is doing multi-thread compilation/execution, paste the information in your
e-mail bellow, and if possible add a test case to reproduce, even if the
error is intermittent?
Thank you
Edson
2008/6/9 Augusto Rodriguez <augusto.rodriguez(a)globant.com>:
Dear All,
We're using Drools in our project and we've been hitting a sporadic error
when we insert Objects in a stateful session. Unfortunately we haven't been
able to reproduce it in a constant way. We tried quite a lot of things but
we haven't been able to track it to the core, but we found a way to
"avoid"
it, but we would love to know why this error is being triggered.
>From time to time we get the following stack trace and usually after this
the rulebase gets broken (all the stateful sessions we generate with it get
unusable) and we can't run anything else in it (we have to restart the app
in order to create a new rule base object).
org.mvel.CompileException: cannot invoke method
at
org.mvel.optimizers.impl.refl.MethodAccessor.getValue(MethodAccessor.java:68)
at
org.mvel.optimizers.impl.refl.VariableAccessor.getValue(VariableAccessor.java:39)
at
org.mvel.ast.VariableDeepPropertyNode.getReducedValueAccelerated(VariableDeepPropertyNode.java:22)
at
org.mvel.ast.PropertyASTNode.getReducedValueAccelerated(PropertyASTNode.java:21)
at org.mvel.MVELRuntime.execute(MVELRuntime.java:88)
at org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
at org.mvel.MVEL.executeExpression(MVEL.java:252)
at
org.drools.base.dataproviders.MVELDataProvider.getResults(MVELDataProvider.java:45)
at org.drools.reteoo.FromNode.assertTuple(FromNode.java:64)
at
org.drools.reteoo.SingleTupleSinkAdapter.createAndPropagateAssertTuple(SingleTupleSinkAdapter.java:55)
at
org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:116)
at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:22)
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:140)
at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:318)
at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:153)
at org.drools.reteoo.Rete.assertObject(Rete.java:175)
at
org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
at
org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:909)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:881)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:682)
at
uk.co.vodco.sherbet.ccp.rules.availability.AvailabilityRulesEngineImpl.addProgramme(AvailabilityRulesEngineImpl.java:27)
[removed a few lines]
Caused by: java.lang.IllegalArgumentException:
java.lang.ClassCastException@1366d44
at sun.reflect.GeneratedMethodAccessor194.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at
org.mvel.optimizers.impl.refl.MethodAccessor.getValue(MethodAccessor.java:64)
... 69 common frames omitted
We found that adding a line to a few rules like the following one removed
the error:
# given the version, add the programme if it does not exist
*rule* "insertion of programme given a version"
*ruleflow-group* "source-defaults"
* when*
$v: ProgrammeVersion()
$p: Programme() *from* $v.getProgramme()
* not* Programme(*this* == $p)
* then
insert* ($p);
* update* ($v); *<-- Added Line*
LoggerFactory.getLogger("factinsertion.drl").info("Entered:
insertion of programme given version");
*end*
** **
Does anyone have an idea of what can be causing this error? We suppose it's
related to the *from* clause in the condition. Because we're taking the
object we're inserting in the working memory ($p) from the object $v, so in
the end, for some reason, we also need to update $v.
Thanks in advance!
Augusto
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--
Edson Tirelli
JBoss Drools Core Development
Office: +55 11 3529-6000
Mobile: +55 11 9287-5646
JBoss, a division of Red Hat @ www.jboss.com
6014
days inactive
6015
days old
2 comments
3 participants
participants (3)
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Augusto Rodriguez -
Edson Tirelli -
PassiveReality