[rules-users] Using KnowledgeAgent with Stateful session

[nestabur]

Hi James,

The kind of agents that I'm using are not the same as you pointed me ;)

I'm just using the agents provided by drools-core for updating the RuleBase.

Anyway, thanks for your suggestion. the FIPA technology seems to be great
for future projects ;)

Thanks for replying,

Nestor


James Owen-3 wrote:
> 
> Greetings:
> 
> Nobody seems to be replying and I'm not really "qualified" to reply  
> but I might be able to point you in the right direction.  Long, long  
> ago in a land far, far away we did a really cool project using  
> Intelligent Agents and employed most of the technology from FIPA, The  
> Foundation for Intelligent Physical Agents; see http://www.fipa.org/  
> for more information.
> 
> SDG
> James Owen
> Founder October Rules Fest
> Senior Consultant / Architect KBSC
> http://www.kbsc.com
> http://www.OctoberRulesFest.org
> Twitter: OctRulesFest
> Blogs:
> http://JavaRules.blogspot.com [Rulebased Systems Blog]
> http://ORF2009.blogspot.com [October Rules Fest Blog]
> http://exscg.blogspot.com/ [Expert Systems Consulting Group Blog]
> 
> "If I have seen a little further it is by standing on the shoulders of  
> giants."
> Sir Isaac Newton in a letter to Robert Hooke, 5 Feb 1676
> 
> Come to October Rules Fest and stand on the shoulders of the Giants of  
> the industry; if only for a week.
> 
> 
> 
> On Aug 26, 2009, at 11:34 AM, nestabur wrote:
> 
>>
>>
>> Does anyone tried to use the knowledgeAgent with statefulSessions?
>>
>> I've tried to configure my rule engine obtaining unexpected behaviour.
>>
>> I configure my statefulSession as follows:
>>
>> wm = (ReteooStatefulSession) ((KnowledgeBaseImpl) kagent
>> 				.getKnowledgeBase()).ruleBase.newStatefulSession(
>> 				(SessionConfiguration) sessionConf, env);
>> ksession = new StatefulKnowledgeSessionImpl(wm,  
>> kagent.getKnowledgeBase());
>>
>> And after updating the KnowledgeBase in the agent I update my  
>> ksession:
>>
>> wm.setRuleBase((InternalRuleBase) ((KnowledgeBaseImpl) kagent
>> 						.getKnowledgeBase()).ruleBase);		
>> ksession = new StatefulKnowledgeSessionImpl(wm,  
>> kagent.getKnowledgeBase());
>>
>> Without using entry-points this approach works as expected, but  
>> using them
>> it fails after the first update throwing the error:
>>
>> Exception while processing message: java.lang.NullPointerException
>> java.lang.NullPointerException
>> 	at
>> org 
>> .drools 
>> .reteoo 
>> .ReteooFactHandleFactory.newFactHandle(ReteooFactHandleFactory.java: 
>> 54)
>> 	at
>> org 
>> .drools 
>> .common 
>> .AbstractFactHandleFactory 
>> .newFactHandle(AbstractFactHandleFactory.java:79)
>> 	at
>> org 
>> .drools 
>> .common 
>> .AbstractFactHandleFactory 
>> .newFactHandle(AbstractFactHandleFactory.java:66)
>> 	at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:109)
>> 	at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:80)
>> 	at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:28)
>>
>> Browsing the drools core code I found the line that was throwing the
>> exception and tried to get the same result by implementing:
>>
>> if (!((InternalRuleBase) ((KnowledgeBaseImpl)
>> ksession.getKnowledgeBase()).ruleBase)
>> 				.getTypeDeclaration(fact.getClass()) == null)
>> 	log.info (((InternalRuleBase) ((KnowledgeBaseImpl)
>> ksession.getKnowledgeBase()).ruleBase)
>> 				
>> .getTypeDeclaration 
>> (fact.getClass()).getTimestampExtractor().toString());
>>
>> after updating my ksession. The result was the same, again the same
>> exception thrown but my logger wrote:
>> 18:01:50,232 INFO [ClassFieldExtractor class=MyPackage.MyFact
>> field=myTimestampField]
>>
>> So I dont know why the core is throwing that exception, is that
>> implementation correct?, any ideas?
>>
>>
>> Thanks,
>>
>> Nestor
>>
>> -- 
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>> Sent from the drools - user mailing list archive at Nabble.com.
>>
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> 
> 
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