Hi, we are trying to call drools api from servlet by using KnowledgeBuilderFactory and proving drl path and creating knowledge base and session but when i am gonna fireRule it is giving me compile time error. I am pasting the log below. Aug 9, 2013 10:17:11 AM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Servlet.service() for servlet dispatcher threw exception java.lang.NoClassDefFoundError: org/drools/builder/KnowledgeBuilderFactory at com.maxmechanics.controller.MMController.fireRulesAndGetResponse(MMController.java:467) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:439) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:427) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:915) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:811) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:796) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) this error is coming while initializing knowledgefactory. KnowledgeBuilder kbuilder = KnowledgeBuilderFactory .newKnowledgeBuilder(); -- View this message in context: http://drools.46999.n3.nabble.com/calling-kbuilder-API-from-jsp-and-servl... Sent from the Drools: User forum mailing list archive at Nabble.com.