Hey Demian, 

thank you! This might actually be related. But how do I get the reference to these Operators to (re)set them?

This is my unmarshalling code (pretty simple and basic..):

ByteArrayInputStream bais = new ByteArrayInputStream(serializedKnowledgeBase);
ObjectInputStream ois = new ObjectInputStream(bais);
kbase = (KnowledgeBase)ois.readObject();

Marshaller marshaller = MarshallerFactory.newMarshaller(kbase);
ByteArrayInputStream bais2 = new ByteArrayInputStream(serializedKnowledgeSession);
knowledgeSession = marshaller.unmarshall(bais2);

Also: Is this going to be fixed in 5.6.0 ? (@Mark Proctor?)

- Alex


On 11.10.2013, at 16:09, Demian Calcaprina <calcacuervo@gmail.com> wrote:

Hey Alexander, 

Would this be related to this?

https://issues.jboss.org/browse/DROOLS-243

If it is this one, you can do something like this as a workaround before constructing the KBase:

Operator op = BeforeEvaluatorDefinition.BEFORE;
Operator op = AfterEvaluatorDefinition.AFTER;

This will cause the evaluation definition to be put in  memory.

Hope this helps!

Demian


On Fri, Oct 11, 2013 at 9:21 AM, Alexander Wolf <mail@alexander-wolf.net> wrote:
[Drools 5.5.0 Final]

I wrote a webserver that keeps StatefulKnowledgeSessions running in Stream mode. When the server is stopped, the sessions are serialized and stored in a database. When the server is restarted, the existing sessions are restored / deserialized.

Some time after recreating the session and inserting some events I get the following exception:

java.lang.NullPointerException: null
at org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:351)
...

Apparently the exception seems to be related to a rule that uses temporal reasoning.
After getting it once, the session seems to be corrupt -> from now on every time I call ksession.insert(event) the same exception occurs.
When I serialize the session and attempt to deserialize it, I get a long stack trace --> I can not deserialize it anymore. (as apparently it is corrupted).
When I run the server with the same events/sessions without stopping (serialization/deserialization) the exception does not occur)

Can I do anything to prevent this behaviour? I thought maybe the "after" timer/trigger is somehow still active when I serialize the ksession.
I tried ksession.halt() before serialization, but with no effect.

Any ideas?

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