David Zeigler wrote: 
Hi Mark,
Thanks for the quick reply.

Now I'm getting a NullPointerException when I insert the message into
the pipeline using 5.0.1.SNAPSHOT from today:
java.lang.NullPointerException
	at org.drools.runtime.pipeline.impl.StatelessKnowledgeSessionPipelineImpl.insert(StatelessKnowledgeSessionPipelineImpl.java:24)

It looks like StatelessKnowledgeSession's ruleBase is null when
created by the KnowledgeAgent, which poses a problem since
StatelessKnowledgeSessionPipelineImpl invokes getRootClassLoader() on
the session's ruleBase.

Here's what I'm doing:
StatelessKnowledgeSession ksession = kagent.newStatelessKnowledgeSession();
Pipeline pipeline =
PipelineFactory.newStatelessKnowledgeSessionPipeline(ksession);
pipeline.setReceiver(messageTransformer);
pipeline.insert(message);  // NPE here
I'm a bit busy to look into this in detail. But there is a unit test for this:
http://anonsvn.labs.jboss.com/labs/jbossrules/trunk/drools-compiler/src/test/java/org/drools/agent/KnowledgeAgentTest.java
testModifyFileUrlWithStateless

That test works, maybe you could do an adaption of that unit test to make it fail and we can add it to the test framework, and which also means I'll fix it asap, if it's a bug.

Mark
Thanks,
David

2009/5/12 Mark Proctor <mproctor@codehaus.org>:
  
David Zeigler wrote:

Hi,
I've set up the KnowledgeAgent to automatically reload the rules
resources if they change.  If I use this with a Pipeline, it seems
that its StatelessKnowledgeSession is not reloaded automatically.  The
only way I've been able to get the Pipeline to reflect the rules
change is to do the following prior to each pipeline.insert():

StatelessKnowledgeSession ksession =
kagent.getKnowledgeBase().newStatelessKnowledgeSession();
Pipeline pipeline =
PipelineFactory.newStatelessKnowledgeSessionPipeline(ksession);
pipeline.setReceiver( messageTransformer );

Reloading the pipeline for each request adds a lot of overhead (halves
my transactions per second).  Is there a way to automatically reload
the Pipeline's session when its needed instead of recreating the
Pipeline prior to each insert?  I see there is a
ResourceChangeListener interface that I could probably use to
accomplish this, but I figured I'd ask in case there is a better way
to handle this case with pipelines.  What's the best approach?


Try trunk, it has a fix for this. Where if you get the
StatelessKnowledgeSession directly from the knowledgeagent every execute
will check for a new KnowledgeBase.
https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/

https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/javadocs/stable/drools-api/org/drools/agent/KnowledgeAgent.html
KnowledgeAgent.newStatelessKnowledgeSession(KnowledgeSessionConfiguration conf)
 StatelessKnowledgeSession created from here will always have the execute()
method called against the latest built KnowledgeBase.

So now you can just use that returned session with the pipeline and it
should always be using the latest rules.

Mark

I'm using 5.0.0.CR1.

Thanks!
David
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