Using the latest JBPM installer demo setup, I have a simple program. It has an object called person with a name and a salary. In guvonor there is a simple rule that I scaled back from the original to try to see what is happening. If I have a condition (salary >= 5000) it gives a null exception, if I remove the condition it works fine. The new fact is inserted and I can see it from my program. Just starting experimenting with guvonor and have been following the threads on changeset but don't have a complete grasp on it yet. Thanks in advance, Jim K. rule "PersonWIthHighIncome" no-loop true dialect "mvel" when Person( salary >= 5000 ) then Person fact0 = new Person(); fact0.setName( "Joe" ); fact0.setSalary( 34465 ); insert(fact0 ); end This results in the following exception: java.lang.NullPointerException at org.drools.impl.KnowledgeBaseImpl.addKnowledgePackages(KnowledgeBaseImpl.java:148) at org.drools.agent.impl.KnowledgeAgentImpl.addResourcesToKnowledgeBase(KnowledgeAgentImpl.java:1016) at org.drools.agent.impl.KnowledgeAgentImpl.rebuildResources(KnowledgeAgentImpl.java:785) at org.drools.agent.impl.KnowledgeAgentImpl.buildKnowledgeBase(KnowledgeAgentImpl.java:657) at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:190) at org.drools.agent.impl.KnowledgeAgentImpl.applyChangeSet(KnowledgeAgentImpl.java:169) at simpleBank.SimpleBank.createKnowledgeBase(SimpleBank.java:64) at simpleBank.SimpleBank.main(SimpleBank.java:27) Code calling the package package simpleBank; import java.util.ArrayList; import java.util.Iterator; import org.drools.KnowledgeBase; import org.drools.KnowledgeBaseFactory; import org.drools.agent.KnowledgeAgent; import org.drools.agent.KnowledgeAgentConfiguration; import org.drools.agent.KnowledgeAgentFactory; import org.drools.builder.KnowledgeBuilder; import org.drools.builder.KnowledgeBuilderError; import org.drools.builder.KnowledgeBuilderErrors; import org.drools.builder.KnowledgeBuilderFactory; import org.drools.builder.ResourceType; import org.drools.io.ResourceFactory; import org.drools.logger.KnowledgeRuntimeLogger; import org.drools.logger.KnowledgeRuntimeLoggerFactory; import org.drools.runtime.StatefulKnowledgeSession; public class SimpleBank { public static void main(String[] args) { try { // load up the knowledge base //KnowledgeBase kbase = readKnowledgeBase(); KnowledgeBase kbase = createKnowledgeBase(); StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession(); //KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory.newFileLogger(ksession, "test"); KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory.newThreadedFileLogger(ksession, "Test2", 1); // go ! insert one person Person person = new Person(); person.setSalary((long) 6000); person.setName("Jim"); System.out.println(person.getName()); ksession.insert(person); assertTrue(ksession.getFactCount() == 1); ksession.fireAllRules(); // rules should have added another fact assertTrue(ksession.getFactCount() != 1); ArrayList<Person> listoffacts = new ArrayList(ksession.getObjects()); System.out.println(listoffacts.size()); Iterator<Person> itr = listoffacts.iterator(); while (itr.hasNext()){ Person element = itr.next(); System.out.println(element.getName() + ":" + element.getSalary().toString()); } logger.close(); } catch (Throwable t) { t.printStackTrace(); } } private static KnowledgeBase createKnowledgeBase() throws Exception{ KnowledgeAgentConfiguration kaconf = KnowledgeAgentFactory.newKnowledgeAgentConfiguration(); kaconf.setProperty( "drools.agent.scanDirectories", "false" ); KnowledgeAgent kagent = KnowledgeAgentFactory.newKnowledgeAgent( "test agent", kaconf ); kagent.applyChangeSet(ResourceFactory.newUrlResource( "http://localhost:8080/drools-guvnor/org.drools.guvnor.Guvnor/package/SalesModel/LATEST/ChangeSet.xml" )); // kagent.applyChangeSet( ResourceFactory.newClassPathResource("ChangeSet.xml")); return kagent.getKnowledgeBase(); } private static void assertTrue(boolean b) { if (b) { System.out.println("Good number of facts"); } else { System.out.println("Bad number of facts"); } } } -- View this message in context: http://drools.46999.n3.nabble.com/Null-pointer-exception-after-adding-Whe... Sent from the Drools: User forum mailing list archive at Nabble.com.