Error inserting facts after session restore -------------------------------------------- Key: DROOLS-102 URL: https://issues.jboss.org/browse/DROOLS-102 Project: Drools Issue Type: Bug Security Level: Public(Everyone can see) Affects Versions: 5.5.0.Final Environment: JBoss AS 5.0 Drools 5.4.0 / 5.5.0 Linux Ubuntu JDK 1.6 Reporter: Nedo Nedic Assignee: Mario Fusco Labels: drools-core I'm using Drools 5.4.0 (but also tried it with the last release of Drools 5.5.0) to save the session state when the application server restarts / stops. Everything works fine and the session state is properly restored, but when new fact is inserted the following exception is thrown: java.lang.NullPointerException at java.lang.Class.isAssignableFrom(Native Method) at org.drools.reteoo.ReteooFactHandleFactory.newFactHandle(ReteooFactHandleFactory.java:57) at org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:68) at org.drools.common.AbstractFactHandleFactory.newFactHandle(AbstractFactHandleFactory.java:53) at org.drools.common.NamedEntryPoint.createHandle(NamedEntryPoint.java:745) at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:287) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:888) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:847) at org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:269) I explored through Drools code, and figured out time stamp extractor getExtractToClass method is evaluating to null (line 57 ReteooFactHandleFactory): public final InternalFactHandle newFactHandle(final int id, final Object object, final long recency, final ObjectTypeConf conf, final InternalWorkingMemory workingMemory, final WorkingMemoryEntryPoint wmEntryPoint) { if ( conf != null && conf.isEvent() ) { TypeDeclaration type = conf.getTypeDeclaration(); long timestamp; if ( type.getTimestampExtractor() != null ) { if ( Date.class.isAssignableFrom( type.getTimestampExtractor().getExtractToClass() ) ) { timestamp = ((Date) type.getTimestampExtractor().getValue( workingMemory, object )).getTime(); } else { timestamp = type.getTimestampExtractor().getLongValue( workingMemory, object ); } } else { timestamp = workingMemory.getTimerService().getCurrentTime(); .... My code for storing / restoring session: public void saveCorrelator(FileOutputStream output) throws IOException { DroolsObjectOutputStream droolsOut = new DroolsObjectOutputStream(output); droolsOut.writeObject(ksession.getKnowledgeBase()); Marshaller mas = createMarshaller(ksession.getKnowledgeBase()); mas.marshall(droolsOut, ksession); droolsOut.flush(); droolsOut.close(); } public void loadCorrelator(FileInputStream input) throws IOException, ClassNotFoundException { DroolsObjectInputStream droolsIn = new DroolsObjectInputStream(input, this.getClass().getClassLoader()); try { KnowledgeBase kbase = (KnowledgeBase) droolsIn.readObject(); Marshaller mas = createMarshaller(kbase); ksession = mas.unmarshall(droolsIn); } catch(EOFException e) { log.error("EOFException on correlator restore"); } finally { droolsIn.close(); } } private Marshaller createMarshaller(KnowledgeBase kbase) { ObjectMarshallingStrategyAcceptor acceptor = MarshallerFactory .newClassFilterAcceptor(new String[] { "*.*" }); ObjectMarshallingStrategy strategy = MarshallerFactory .newSerializeMarshallingStrategy(acceptor); return MarshallerFactory.newMarshaller(kbase, new ObjectMarshallingStrategy[] { strategy }); }