[jboss-jira] [JBoss JIRA] (DROOLS-1158) NullpointerException when trying to reuse KnowledgePackage into a new KnowledgeBase

[Matteo Mortari (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-1158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13264760#comment-13264760 ] 

Matteo Mortari commented on DROOLS-1158:
----------------------------------------

Hello [~jcgarciam], I've checked your description and your reproducer, but I would kindly request for your feedback on the following questions, please?
.

* I've run the reproducer but it does not trigger the error/stacktrace you reported. Ref. screenshot:
!screenshot-1.png|thumbnail!
I've just added slf4j-log4j dependency in order to see some drools logs, but your code left unchanged indeed does not reproduce the error/stacktrace you reported.
Additionally, I've tried to increase the timeout in the test, still nothing. I've moved drools version from 6.4.0.Final originally in your reproducer, to 6.3.0.Final as you reported that was also an issue, still nothing. Can you advise on the attached reproducer please, because is not triggering the error/stacktrace you reported.

Then I've explored your code, and I think part of it is using internal API. Based on your use-case scenario reported in the description above (summarizing: _avoiding, as possible, to completely rebuild the KB from the XLS files where most are unchanged_), I'm wondering:
# wouldn't the KieScanner to monitor KJAR update be easier to use for this use-case scenario?
Being the incremental update based at resource level, I was expecting should have addressed your need described.
# if the KieScanner/KJAR usage is not suitable for any reason, wouldn't it be easier to use the public Kie API to build the KieModule in programmatically, say following the example ["4.2.6.10. Programmaticaly build a KieModule using Meta Models"|http://docs.jboss.org/drools/release/6.4.0.Final/drools-docs/html_single/index.html#d0e3917] ?
(trying to anticipate a possible follow-up question, on top of my head with that API I'm not sure you can re-use KiePackages originating from another KieBase, but you should be able to keep the manual caching currently done at least for the rendering of XLS in DRL form?)

I hope this at least partially helps, and kindly awaiting for your feedback; thank you.
MM

> NullpointerException when trying to reuse KnowledgePackage into a new KnowledgeBase
> -----------------------------------------------------------------------------------
>
>                 Key: DROOLS-1158
>                 URL: https://issues.jboss.org/browse/DROOLS-1158
>             Project: Drools
>          Issue Type: Bug
>    Affects Versions: 6.3.0.Final, 6.4.0.Final
>            Reporter: Juan Carlos Garcia
>            Assignee: Mario Fusco
>         Attachments: drools-reusepackage.tar, screenshot-1.png
>
>
> Having a set of DecisionTables which KnowledgePackages are cached in our application, after we detect a change in any of those XLS files, we build a KnowledgePackages from it, and then try to create a new KnowledgeBase with the new KnowledgePackages + the rest of the cached one that that were not modified, but it fails with a NPE internally in Drools (6.3.0 and 6.4.0)
> This is not a problem for the drools version (6.0.1.Final) that we currently uses using in production.
> After debugging and putting a breakpoint into the *MvelConstraint.java:619*,  it shows that it is trying to look for a packageName which hasn't being loaded yet in the new kbase (but belong to others XLS).
> I have attached a project with a testcase that shows the problem, it has 2 DecisionTable which i had to cut down a little bit (from our real files) and removes some sensitive information (replacing some of text with FOO-BAR).
> {code}
> java.lang.NullPointerException
>         at org.drools.core.rule.constraint.MvelConstraint.equals(MvelConstraint.java:619)
>         at org.drools.core.reteoo.AlphaNode.internalEquals(AlphaNode.java:199)
>         at org.drools.core.common.BaseNode.thisNodeEquals(BaseNode.java:194)
>         at org.drools.core.reteoo.CompositeObjectSinkAdapter.getMatchingNode(CompositeObjectSinkAdapter.java:531)
>         at org.drools.core.reteoo.builder.BuildUtils.attachNode(BuildUtils.java:121)
>         at org.drools.core.reteoo.builder.PatternBuilder.buildAlphaNodeChain(PatternBuilder.java:332)
>         at org.drools.core.reteoo.builder.PatternBuilder.attachAlphaNodes(PatternBuilder.java:313)
>         at org.drools.core.reteoo.builder.PatternBuilder.attachPattern(PatternBuilder.java:130)
>         at org.drools.core.reteoo.builder.PatternBuilder.build(PatternBuilder.java:78)
>         at org.drools.core.reteoo.builder.GroupElementBuilder$AndBuilder.build(GroupElementBuilder.java:108)
>         at org.drools.core.reteoo.builder.GroupElementBuilder.build(GroupElementBuilder.java:68)
>         at org.drools.core.reteoo.builder.ReteooRuleBuilder.addSubRule(ReteooRuleBuilder.java:161)
>         at org.drools.core.reteoo.builder.ReteooRuleBuilder.addRule(ReteooRuleBuilder.java:133)
>         at org.drools.core.reteoo.ReteooBuilder.addRule(ReteooBuilder.java:106)
>         at org.drools.core.impl.KnowledgeBaseImpl.addRule(KnowledgeBaseImpl.java:1567)
>         at org.drools.core.impl.KnowledgeBaseImpl.addRule(KnowledgeBaseImpl.java:1547)
>         at org.drools.core.impl.KnowledgeBaseImpl.internalAddPackages(KnowledgeBaseImpl.java:920)
>         at org.drools.core.impl.KnowledgeBaseImpl.access$000(KnowledgeBaseImpl.java:117)
>         at org.drools.core.impl.KnowledgeBaseImpl$1.run(KnowledgeBaseImpl.java:708)
>         at org.drools.core.impl.KnowledgeBaseImpl.enqueueModification(KnowledgeBaseImpl.java:716)
>         at org.drools.core.impl.KnowledgeBaseImpl.addPackages(KnowledgeBaseImpl.java:705)
>         at org.drools.core.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:273)
>         at org.drools.impl.adapters.KnowledgeBaseAdapter.addKnowledgePackages(KnowledgeBaseAdapter.java:62)
>         at bug.demo.BugReloadableDecisionTableTest.addRuleSetToKnowledgeBase(BugReloadableDecisionTableTest.java:63)
>         at bug.demo.BugReloadableDecisionTableTest.testReuseKnowledgePackage(BugReloadableDecisionTableTest.java:53)
> {code}



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