Re: [rules-users] removeKnowledgePackage Call Hangs!!
Why are you trying to remove a knowledge package while you are in the middle of running
rules? I'm not a drools developer and don't know whether it has been designed to
allow this area of code to be re-entrant but to me it seems like you are trying to pull
the rug (or at least part of it) out from underneath it. I'd assume that you are
getting null pointers because rules that are on the activation queue are suddenly no
longer present in the knowledge base, or some other similar reason.
There's probably two other approaches that you could take which may be safer:
1. Each rule have an activation object (shared across a rules package). They will only
fire if the appropriate package is in the knowledge base, when you no longer want a set of
rules to fire then you remove the appropriate activation object.
2. Don't remove the knowledge packages while the rules are still running, instead
populate a list of packages which need removing, either stored within the knowledgebase or
using a global to pass it back to the application. When you want to change the knowledge
package have your rule export the package you want to remove and then use the context to
abort the firing of the knowledge session. Your application code can then remove the
knowledge packages you have selected and then restart the firing of the session.
Thomas
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-
bounces(a)lists.jboss.org] On Behalf Of malkhafaji
Sent: 17 May 2010 20:35
To: rules-users(a)lists.jboss.org
Subject: Re: [rules-users] removeKnowledgePackage Call Hangs!!
Any help is appreciated. I am stuck on this. I stripped everything down to
two simple drls, and one of them loads the other as a new KP, and then tries
to unload it.
Any ideas why the removeKnowledgePackage could possibly throw a
NullPointerException in M1?? This is really hurting us as we are going live
with this in a couple of weeks or so.
Any help would be greatly appreciated!
--
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