Field Injection in Intermediate Throw event

[mattd...@gmail.com]

Hi guys,

I am trying to make use of field injection, with a class delegate, but my field values do not seem to be set by the process engine.

When using the below BPMN and JavaDelegate, the field values are always null, when the process instance executes the delegate code.

I created the below BPMN using the latest version of the Camunda modeller. Am I missing something or is this a genuine bug?

<bpmn2:intermediateThrowEvent id="IntermediateThrowEvent_1">
<bpmn2:extensionElements>
<camunda:field name="messageName">
<camunda:string>triggerMessage</camunda:string>
</camunda:field>
</bpmn2:extensionElements>
<bpmn2:incoming>SequenceFlow_1</bpmn2:incoming>
<bpmn2:outgoing>SequenceFlow_2</bpmn2:outgoing>
<bpmn2:messageEventDefinition id="_MessageEventDefinition_6" camunda:class="com.telrock.platform.themis.testpa.delegate.SendMessageDelegate"/>
</bpmn2:intermediateThrowEvent>

package com.telrock.platform.themis.testpa.delegate;

import java.util.HashMap;

public class SendMessageDelegate implements JavaDelegate
{
private Expression messageName;
private Expression variables;

@Override
@SuppressWarnings("unchecked")
public void execute(DelegateExecution execution) throws Exception
{
if (messageName == null)
{
throw new BpmnError(BpmnUtils.ERROR_MISSING_FIELD, "messageName cannot be null");
}

String message = messageName.getValue(execution).toString();

Map<String, Object> variableMap = null;
try
{
variableMap = variables != null ? (Map<String, Object>) variables.getValue(execution)
: new HashMap<String, Object>();
}
catch (ClassCastException e)
{
throw new BpmnError(BpmnUtils.ERROR_INCORRECT_FIELD_TYPE, "variables must resolve to a map<String,Object>");
}

String businessKey = execution.getProcessBusinessKey();
if (StringUtils.isBlank(businessKey))
{
execution.getProcessEngineServices().getRuntimeService().correlateMessage(message, variableMap);
}
else
{
execution.getProcessEngineServices().getRuntimeService().correlateMessage(message, businessKey, variableMap);
}
}

public Expression getMessageName()
{
return messageName;
}

public void setMessageName(Expression messageName)
{
this.messageName = messageName;
}

public Expression getVariables()
{
return variables;
}

public void setVariables(Expression variables)
{
this.variables = variables;
}
}

Cheers,
-MattD

[mattd...@gmail.com]

I have since tried the same thing with a Service Task and it works:

<bpmn2:serviceTask id="ServiceTask_3" camunda:class="com.telrock.platform.themis.testpa.delegate.SendMessageDelegate" name="Trigger Process 2">

<bpmn2:extensionElements>
<camunda:field name="messageName">
<camunda:string>triggerMessage</camunda:string>
</camunda:field>
</bpmn2:extensionElements>

<bpmn2:incoming>SequenceFlow_7</bpmn2:incoming>
<bpmn2:outgoing>SequenceFlow_8</bpmn2:outgoing>
</bpmn2:serviceTask>

The above snippet sets the JavaDelegate fields correctly. I can only assume this is a bug in the Intermediate Throwing Message Event, as the docs say that this should be handled the same as the Service Task: http://docs.camunda.org/latest/api-references/bpmn20/#events-message-events-message-intermediate-throwing-event

[Sebastian Menski]

Hi Matt,

the field injections have to be extension elements of the message event definition and not of the intermediate throw event.

So this should work for you:

<bpmn2:intermediateThrowEvent id="IntermediateThrowEvent_1">

  <bpmn2:incoming>SequenceFlow_1</bpmn2:incoming>
  <bpmn2:outgoing>SequenceFlow_2</bpmn2:outgoing>
  <bpmn2:messageEventDefinition id="_MessageEventDefinition_6" camunda:class="com.telrock.platform.themis.testpa.delegate.SendMessageDelegate">

   
    <bpmn2:extensionElements>

      <camunda:field name="messageName">
        <camunda:string>triggerMessage</camunda:string>
      </camunda:field>
    </bpmn2:extensionElements>

  </bpmn2:messageEventDefinition>
</bpmn2:intermediateThrowEvent>

Cheers,

Sebastian

[mattd...@gmail.com]

Hi Sebastian,

Thanks for your response. That does make sense to me, unfortuenately the Modeller, and the xsd: <bpmn2:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:camunda="http://activiti.org/bpmn" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd" id="_WsQkYPIMEeOco9VopC8wwg" exporter="camunda modeler" exporterVersion="2.5.0" targetNamespace="http://activiti.org/bpmn">, does not allow me to generate BPMN like that.

For now I'll have to stick to using the Send or Service Task I think.

Cheers,
-MattD

[Sebastian Menski]

Hi Matt,

it is correct that there is no way to configure the field injection of a message event definition with the Design view of the modeler. But I was able

to add them in the Source view with the last modeler release (1.2.0). Is this no option for you? I'm not sure why you think the xsd does not allow you to do this?

Cheers,
Sebastian