stellina_rosa [http://community.jboss.org/people/stellina_rosa] created the discussion "Unable to create Field Extractor" To view the discussion, visit: http://community.jboss.org/message/606688#606688 -------------------------------------------------------------- h6. Hi! h6. I'm trying to create an example Drools file but when I run it I have this error message: h6. h6. h6. Unable to create Field Extractor for 'contenuto' of '[ClassObjectType class="java".lang.Object]' in rule 'prova' : [Rule name='prova'] java.lang.IllegalArgumentException: Could not parse knowledge.           at org.drools.builder.impl.KnowledgeBuilderImpl.newKnowledgeBase(KnowledgeBuilderImpl.java:58)           at com.sample.ProcessTest.readKnowledgeBase(ProcessTest.java:43)           at com.sample.ProcessTest.main(ProcessTest.java:21) h6. this is my drools file (named Rule.drl): package com.googlecode.cursos.jbpm import org.drools.runtime.process.WorkflowProcessInstance; import org.sample.model.MyObject; rule "prova"           ruleflow-group "regole"           when                     $o: Object(contenuto == "rosa")           then            System.out.println("prima regola"); end h6. this is my ProcessTest.java class: public class ProcessTest {           public static final void main(String[] args) {                     try {                               // load up the knowledge base                               KnowledgeBase kbase = readKnowledgeBase();                               StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();                               KnowledgeRuntimeLogger logger = KnowledgeRuntimeLoggerFactory.newFileLogger(ksession, "test");                               MyObject obj = new MyObject();                               obj.setContenuto("rosa");                               obj.setId(1);                               ksession.insert(obj);                               // start a new process instance                               ksession.startProcess("com.sample.bpmn.hello");                               ksession.fireAllRules();                               logger.close();                     } catch (Throwable t) {                               t.printStackTrace();                     }           } private static KnowledgeBase readKnowledgeBase() throws Exception {   KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();   kbuilder.add(ResourceFactory.newClassPathResource("sample.bpmn"), ResourceType.BPMN2);   kbuilder.add(ResourceFactory.newClassPathResource("Rule.drl"), ResourceType.DRL);   return kbuilder.newKnowledgeBase();   } h6. and this is my MyObject.java class: package org.sample.model; public class MyObject {           String contenuto;           int id;           public int getId() { return id;} public void setId(int id) { this.id = id; } public String getContenuto() { return contenuto; } public void setContenuto(String contenuto) { this.contenuto = contenuto;} } I can't understand where is the problem :( could anyone help me please? thank you! -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/606688#606688] Start a new discussion in jBPM at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&...]