Claus Straube [http://community.jboss.org/people/clauss] replied to the discussion "NPE while serviceTask call" To view the discussion, visit: http://community.jboss.org/message/534980#534980 -------------------------------------------------------------- arrrrg - found the mistake (of course one minute after my post). Here is the correct code: <?xml version="1.0" encoding="UTF-8"?> <bpmn:definitions id="ServiceTaskJava"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xsi:schemaLocation="http://schema.omg.org/spec/BPMN/2.0 BPMN20.xsd"     xmlns:bpmn="http://schema.omg.org/spec/BPMN/2.0" typeLanguage="http://www.w3.org/2001/XMLSchema"     expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://sample.bpmn.camunda.com/"     xmlns:jbpm="http://jbpm.org/4.0/bpmn2">     <bpmn:itemDefinition id="i1">         <jbpm:arg>             <jbpm:object expr="#{instanceId}" />         </jbpm:arg>     </bpmn:itemDefinition>     <bpmn:itemDefinition id="i2">         <jbpm:var name="v1" />     </bpmn:itemDefinition>     <bpmn:message id="im" name="input message"         structureRef="i1"></bpmn:message>     <bpmn:message id="om" name="output message"         structureRef="i2">     </bpmn:message>     <bpmn:interface id="if1" name="mocks.Mock01">         <bpmn:operation id="o1" name="call">             <bpmn:inMessageRef>im</bpmn:inMessageRef>             <bpmn:outMessageRef>om</bpmn:outMessageRef>         </bpmn:operation>     </bpmn:interface>     <!-- process definition -->     <bpmn:process id="foobar" name="async_process">         <bpmn:startEvent id="s" />                 <bpmn:sequenceFlow id="f1" name="s_2_r1" sourceRef="s" targetRef="r1" />         <bpmn:receiveTask id="r1" name="r1" />                 <!-- -->         <bpmn:sequenceFlow id="f2" name="r1_2_t1" sourceRef="r1" targetRef="st1" />         <bpmn:serviceTask id="st1" name="st1" implementation="Other" operationRef="o1"/>                 <bpmn:sequenceFlow id="f3" name="st1_2_r2" sourceRef="st1" targetRef="r2" />         <!-- -->                 <!--         <bpmn:sequenceFlow id="fx" name="r1_2_r2" sourceRef="r1" targetRef="r2" />         -->                 <bpmn:receiveTask id="r2" name="r2" />                 <bpmn:sequenceFlow id="f4" name="r2_2_e1" sourceRef="r2" targetRef="e1" />         <bpmn:endEvent id="e1" name="e1" />                </bpmn:process> </bpmn:definitions> The problem was the in and out message ref. Best regards - claus -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/534980#534980] Start a new discussion in jBPM at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&...]