[rules-users] Drools and Guvnor 5.1M2 - Exception beingthrowninprocessChangeSet

Thu Jul 1 12:27:57 EDT 2010

Esteban,

Here is the stack trace for the ClassNotFoundException when the compiler
jar is not included.  

java.lang.ClassNotFoundException:
org.drools.builder.impl.KnowledgeBuilderFactoryServiceImpl

     at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader
.java:1387)

     at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader
.java:1233)

     at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)

     at java.lang.Class.forName0(Native Method)

     at java.lang.Class.forName(Class.java:169)

     at
org.drools.util.ServiceRegistryImpl$ReflectionInstantiator.newInstance(S
erviceRegistryImpl.java:190)

     at
org.drools.util.ServiceRegistryImpl$ReflectionInstantiator.call(ServiceR
egistryImpl.java:185)

     at
org.drools.util.ServiceRegistryImpl.get(ServiceRegistryImpl.java:143)

     at
org.drools.builder.KnowledgeBuilderFactory.loadServiceFactory(KnowledgeB
uilderFactory.java:107)

     at
org.drools.builder.KnowledgeBuilderFactory.getKnowledgeBuilderPServiceFa
ctory(KnowledgeBuilderFactory.java:101)

     at
org.drools.builder.KnowledgeBuilderFactory.newKnowledgeBuilder(Knowledge
BuilderFactory.java:29)

     at
org.drools.agent.impl.KnowledgeAgentImpl.createPackageFromResource(Knowl
edgeAgentImpl.java:556)

     at
org.drools.agent.impl.KnowledgeAgentImpl.createPackageFromResource(Knowl
edgeAgentImpl.java:541)

     at
org.drools.agent.impl.KnowledgeAgentImpl.incrementalBuildResources(Knowl
edgeAgentImpl.java:731)

     at
org.drools.agent.impl.KnowledgeAgentImpl.buildKnowledgeBase(KnowledgeAge
ntImpl.java:515)

     at
org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentIm
pl.java:145)

     at
org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentIm
pl.java:130)

Any idea on why the other error is appearing.  The error is
"java.lang.RuntimeException: KnowledgeAgent exception while trying to
deserialize KnowledgeDefinitionsPackage".  This occurs when the
knowledge agent is created with the compiled package from the Guvnor for
the first time.

Thank you for all your work and help.  Drools is a great package.

Thanks.

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Esteban
Aliverti
Sent: Thursday, July 01, 2010 8:09 AM
To: Rules Users List
Subject: Re: [rules-users] Drools and Guvnor 5.1M2 - Exception
beingthrowninprocessChangeSet

Could you please provide us the line number where de
ClassNotFoundException occurs. I think I know what could be happening.
When you use incremental change set processing (newInstance = false),
the agent use a kbuilder to perform some diff between the modified and
original resource. The thing is that the agent always instantiate a
kbuilder even if all the resources are already compiled (which is
useless).

Please provide me the line number of the exception, i will start working
on this issue. Meanwhile, as a workaround, add the drools-compiler
dependency. 

The KAgent was practically rebuilt from scratch since 5.1M1 so these
kind of error were expected ;)

Best,

2010/7/1 Jeffrey Schneller <jeffrey.schneller at envisa.com>

As a follow-up, this did work however there are still some problems.
The rules did get pulled into the application and seem to be running but
clearly something is not right.

I needed to include the drools-compiler.jar in my app otherwise I was
getting a ClassNotFoundException.  I am pulling a compiled package from
the Guvnor so not sure why I need the compiler jar in my app.

When the rules are pulled into the app I am getting the exception thrown
which is being logged and the app can continue running: 

2010-07-01 00:36:14,201 | INFO (MyDroolsListener.java:41) KnowledgeAgent
performing an incremental build of the ChangeSet

2010-07-01 00:36:14,261 | ERROR (MyDroolsListener.java:30)
java.lang.RuntimeException: KnowledgeAgent exception while trying to
deserialize KnowledgeDefinitionsPackage  

2010-07-01 00:36:14,261 | WARN (MyDroolsListener.java:53)
KnowledgeAgent: The resource didn't create any package: [UrlResource
path='http://ruleserver/drools-guvnor/org.drools.guvnor.Guvnor/package/m
y.rule.package/LATEST']

2010-07-01 00:36:14,271 | INFO (MyDroolsListener.java:41) KnowledgeAgent
incremental build of KnowledgeBase finished and in use

Then if I rebuild the package in the Guvnor then I see the following
[the two lines are repeated for each rule in the package]:

[2010:07:182 00:07:741:debug] BinaryResourceDiffProducerImpl: Comparing
[Rule name=v_32, agendaGroup=MAIN, salience=0, no-loop=false] against
[Rule name=v_32, agendaGroup=MAIN, salience=0, no-loop=false]

[2010:07:182 00:07:741:debug] BinaryResourceDiffProducerImpl: The rules
have different LHS

Thanks

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Esteban
Aliverti
Sent: Wednesday, June 30, 2010 6:35 PM

To: Rules Users List
Subject: Re: [rules-users] Drools and Guvnor 5.1M2 - Exception
beingthrownin processChangeSet

The problem seams to happen because the kagent can't access the url. 

If you try to access the change set xml using a browser, does the
browser ask you for authentication? I don't know why, but guvnor protect
its urls since 5.1 I think. 

So, basically, the error is that guvnor can't read from the url. The
same error happens if you provide a non existent url. I need to open a
jira for this.

As a work around, try doing this:

<change-set xmlns='http://drools.org/drools-5.0/change-set
<http://drools.org/drools-5.0/change-set> '

    xmlns:xs='http://www.w3.org/2001/XMLSchema-instance
<http://www.w3.org/2001/XMLSchema-instance> '

    xs:schemaLocation='http://drools.org/drools-5.0/change-set
drools-change-set-5.0.xsd
<http://drools.org/drools-5.0/change-setdrools-change-set-5.0.xsd> ' >

    <add>

         <resource basicAuthentication='enabled' username='admin'
password='admin'
source='http://ruleserver/drools-guvnor/org.drools.guvnor.Guvnor/package
/my.rule.package/LATEST
<http://ruleserver/drools-guvnor/org.drools.guvnor.Guvnor/package/my.rul
e.package/LATEST> ' type='PKG' />

    </add>

</change-set>

Remember to replace username and password.

Best,

2010/6/30 Jeffrey Schneller <jeffrey.schneller at envisa.com>

Here is the xml file I am getting:

<change-set xmlns='http://drools.org/drools-5.0/change-set'

    xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'

    xs:schemaLocation='http://drools.org/drools-5.0/change-set
drools-change-set-5.0.xsd
<http://drools.org/drools-5.0/change-setdrools-change-set-5.0.xsd> ' >

    <add>

         <resource
source='http://ruleserver/drools-guvnor/org.drools.guvnor.Guvnor/package
/my.rule.package/LATEST' type='PKG' />

    </add>

</change-set>

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Esteban
Aliverti
Sent: Wednesday, June 30, 2010 3:18 PM
To: Rules Users List
Subject: Re: [rules-users] Drools and Guvnor 5.1M2 - Exception being
thrownin processChangeSet

Could you please post the xml file you are getting from
http://rulerserver/drools-guvnor/org.drools.guvnor.Guvnor/package/my.rul
e.package/LATEST/ChangeSet.xml
<http://rulerserver/drools-guvnor/org.drools.guvnor.Guvnor/package/my.ru
le.package/LATEST/ChangeSet.xml> ?

Best,

2010/6/30 Jeffrey Schneller <jeffrey.schneller at envisa.com>

I am trying to upgrade to the 5.1M2 build from 5.0.1 and am running into
some issues.  I have installed the new 5.1 Guvnor and imported the rules
from my 5.0.1 Guvnor instance.  

I then removed the old 5.0.1 drools jars from my app and replaced them
with the 5.1M2 drools jars.  I was also added all the dependent
libraries.  The code that worked with the 5.0.1 version does not work
with the 5.1M2 version.  In 5.0.1 I was constructing the xml and
streaming it into the applyChangeSet method.  With 5.1M2 I am just
pointing to the change set xml file that is in the Guvnor. 

I am seeing a NullPointerException being thrown  in the processChangeSet
method as shown below.

Caused by: java.lang.NullPointerException

                at
org.drools.agent.impl.KnowledgeAgentImpl.processChangeSet(KnowledgeAgent
Impl.java:171)

                at
org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentIm
pl.java:143)

                at
org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentIm
pl.java:130)

Did I miss something?  Am I doing something wrong?  Below is the code
that I have.

                 KnowledgeAgentConfiguration kaconf =
KnowledgeAgentFactory.newKnowledgeAgentConfiguration();

                 kaconf.setProperty( "drools.agent.scanDirectories",
"true" ); 

                 kaconf.setProperty("drools.agent.newInstance",
"false");

ResourceFactory.getResourceChangeScannerService().start();

ResourceFactory.getResourceChangeNotifierService().start();

                String url =
"http://rulerserver/drools-guvnor/org.drools.guvnor.Guvnor/package/my.ru
le.package/LATEST/ChangeSet.xml";

                KnowledgeAgent kagent =
KnowledgeAgentFactory.newKnowledgeAgent( "Configuration", kaconf );

                kagent.setSystemEventListener(new MyDroolsListener());

try {

kagent.applyChangeSet(ResourceFactory.newUrlResource(new URL(url)));
// ERROR IS OCCURING INSIDE OF applyChangeSet

                } catch (MalformedURLException e) {

                                e.printStackTrace();

                }

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Esteban Aliverti

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Esteban Aliverti

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Esteban Aliverti

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