(1) Is the originally posted stack trace complete? What you have
posted doesn't make sense.

it is the stack trace complete of this exception. Now I added some other log lines.

If you mean other thing, please let me know.

DEBUG [2012-07-23 16:27:51,374] [Thread-19] (StorageManager.java:778) - Asking a con. to DB: jdbc:postgresql://tass-server/gsn_geo_dev_c => busy: 1, max-size: 8, idle: 2

[java] DEBUG [2012-07-23 16:27:51,375] [Thread-19] (StorageManager.java:457) - Executing query: select * from __435941104 ( Binary Field Linked:false)

[java] DEBUG [2012-07-23 16:27:51,375] [Thread-19] (StorageManager.java:778) - Asking a con. to DB: jdbc:postgresql://tass-server/gsn_geo_dev_c => busy: 2, max-size: 8, idle: 1

[java] DEBUG [2012-07-23 16:27:51,382] [Thread-19] (ObservationFactory.java:226) - org.dfms.model.observation.ACObservation/1343053671381/920/sim_bidv:1343053671381

[java] ERROR [2012-07-23 16:27:51,385] [Thread-19] (ExpertSystemManager.java:162) - java.lang.NullPointerException

[java] java.lang.NullPointerException

[java] at org.drools.reteoo.ReteooFactHandleFactory.newFactHandle(ReteooFactHandleFactory.java:56)

[java] at org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:80)

[java] at org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:65)

[java] at org.drools.common.NamedEntryPoint.createHandle(NamedEntryPoint.java:720)

[java] at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:280)

[java] at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:116)

[java] at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:48)

[java] at org.tass.utils.ExpertSystemManager.insertObservation(ExpertSystemManager.java:156)

[java] at org.tass.vsensor.ExpertVS.dataAvailable(ExpertVS.java:59)

[java] at gsn.beans.InputStream.executeQuery(InputStream.java:277)

[java] at gsn.beans.StreamSource.windowSlided(StreamSource.java:325)

[java] at gsn.beans.windowing.SQLViewQueryRewriter.dataAvailable(SQLViewQueryRewriter.java:83)

[java] at gsn.beans.windowing.TupleBasedSlidingHandler.dataAvailable(TupleBasedSlidingHandler.java:56)

[java] at gsn.wrappers.AbstractWrapper.postStreamElement(AbstractWrapper.java:222)

[java] at gsn.http.rest.LocalDeliveryWrapper.writeStreamElement(LocalDeliveryWrapper.java:147)

[java] at gsn.http.rest.DefaultDistributionRequest.deliverStreamElement(DefaultDistributionRequest.java:57)

[java] at gsn.DataDistributer.flushStreamElement(DataDistributer.java:165)

[java] at gsn.DataDistributer.run(DataDistributer.java:220)

[java] at java.lang.Thread.run(Thread.java:662)

[java] DEBUG [2012-07-23 16:27:51,387] [Thread-19] (VirtualSensor.java:112) - Enforcing the limit size on the VS table by : delete from sim_tassllfvs where sim_tassllfvs.timed <= ( SELECT * FROM ( SELECT timed FROM sim_tassllfvs group by sim_tassllfvs.timed ORDER BY sim_tassllfvs.timed DESC LIMIT 1 offset 5000 ) AS TMP)

[java] DEBUG [2012-07-23 16:27:51,387] [Thread-19] (StorageManager.java:778) - Asking a con. to DB: jdbc:postgresql://tass-server/gsn_geo_dev_c => busy: 1, max-size: 8, idle: 2

[java] DEBUG [2012-07-23 16:27:51,389] [Thread-19] (VirtualSensor.java:119) - 0 old rows dropped from sim_tassllfvs

[java] DEBUG [2012-07-23 16:27:51,391] [Thread-19] (InputStream.java:292) - Input Stream's result has *1* stream elements

> In particular the exception (I mentioned above) happens before calling the
> method "SituationManager.createAccessControlEvent":
>

This isn't possible. The call must have completed, and we're already
in insert().

We are using drools Fusion and then we are inserting some events( ACObservation )

through entry point. Is it possible that the error is related to this insert operation?

Thank you and kindly regards!

Carolina