hi iam working on sample drools project. In that i was dynamically loading a fact ang running the rule engine. Based on the reply from the people of y previous post i have made some modifications. In the Eclipse editor it works fine.but when i call it externally it is throwing the error.I guess class path was recognised by the ruleengine ------------------------------------------------------------------------------------ java class static String path="C:\\Program Files\\Apache Software Foundation\\Tomcat 6.0\\webapps\\JStudio\\WEB-INF\\classes\\"; try{ System.out.println("Initializing Fact...."); URL[] urls = new URL[]{ new URL("file://"+path) }; ClassLoader loader = new URLClassLoader(urls); Class clazz = loader.loadClass("test.Message"); Object factObj = clazz.newInstance(); Method method = clazz.getMethod("setMessage", new Class[]{String.class}); Method method1 = clazz.getMethod("getMessage"); //System.out.println("facts loaded\n"); method.invoke(factObj, new Object[]{"Hello"}); System.out.println("initializing packageBuilder"); PackageBuilderConfiguration config = new PackageBuilderConfiguration(); config.setClassLoader(loader); KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder(config); System.out.println("finding Rule"); kbuilder.add(ResourceFactory.newClassPathResource("test/Sample.drl"),ResourceType.DRL); if (kbuilder.hasErrors()) throw new RuntimeException("Unable to compile rules. " + kbuilder.getErrors().toString()); KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase(new RuleBaseConfiguration(loader)); kbase.addKnowledgePackages(kbuilder.getKnowledgePackages()); StatelessKnowledgeSession session = kbase.newStatelessKnowledgeSession(); System.out.println("running rule....... \n"); session.execute(factObj); System.out.println("\nend...\n"); } catch (Throwable t) { t.printStackTrace(); } --------------------------------------------------------------------------------- tomcat output console http://www.nabble.com/file/p26109542/console.PNG console.PNG suggest me any ideas Hemanth -- View this message in context: http://www.nabble.com/java.lang.NoClassDefFoundError-tp26109542p26109542.... Sent from the drools - user mailing list archive at Nabble.com.