[jboss-user] [jBPM] - dataInputAssociation <assignment> expressions

M Arnold [https://community.jboss.org/people/marnold] created the discussion "dataInputAssociation <assignment> expressions" To view the discussion, visit: https://community.jboss.org/message/647913#647913 -------------------------------------------------------------- Hi, I'm struggling to map input parameters to my task from process variables.  I can't find much documentation besides http://docs.jboss.org/jbpm/v5.2/userguide/ch05.html#sec.data 5.8.1. Data, and the BPMN2 spec from OMG is cryptic. I have a task something like this:         <task id="_4" tns:taskName="Custom" name="sendCustom">             <incoming>_2-_4</incoming>             <outgoing>_4-_5</outgoing>             <ioSpecification id="InputOutputSpecification_1">                 <dataInput id="_4_messageInInput" name="messageIn" />                 <dataOutput id="_4_messageOutOutput" name="messageOut" />                 <inputSet id="InputSet_1">                     <dataInputRefs>_4_messageInInput</dataInputRefs>                 </inputSet>                 <outputSet id="OutputSet_1">                     <dataOutputRefs>_4_messageOutOutput</dataOutputRefs>                 </outputSet>             </ioSpecification>             <dataInputAssociation id="DataInputAssociation_2">                 <sourceRef>event</sourceRef>                 <targetRef>_4_messageInInput</targetRef>                 <assignment id="Assignment_2">                     <from xsi:type="tFormalExpression" id="FormalExpression_3">.</from>                     <to xsi:type="tFormalExpression" id="FormalExpression_4">.</to>                 </assignment>             </dataInputAssociation>             <dataOutputAssociation id="DataOutputAssociation_1">                 <sourceRef>_4_messageOutOutput</sourceRef>                 <targetRef>resultMessage_4</targetRef>             </dataOutputAssociation>         </task> Where 'event' is a process variable.  So what can I put in the <assignment><to> and <from>?  An XPath expression?  What if it's not XML?  When I can I use #{event}?  What are the valid values for from@xsi:type besides "tFormalExpression"? When I execute this task as it is above, I get: Caused by: java.lang.NullPointerException         at org.jbpm.bpmn2.xpath.XPATHAssignmentAction.execute(XPATHAssignmentAction.java:91)         at org.jbpm.workflow.instance.node.WorkItemNodeInstance.handleAssignment(WorkItemNodeInstance.java:193)         ... 81 more I'm sorry if this is a very basic or broad question.  I've scoured the web and really can't find many examples. Thanks in advance for help. -------------------------------------------------------------- Reply to this message by going to Community [https://community.jboss.org/message/647913#647913] Start a new discussion in jBPM at Community [https://community.jboss.org/choose-container!input.jspa?contentType=1&...]