Example of scripting with camunda BPM

camunda-bpm-scripting-example.xml

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xmlns:camunda="http://activiti.org/bpmn"
             targetNamespace="http://camunda.org/exmaples">
  <process id="testProcess" isExecutable="true">
    <startEvent id="startEvent" />
    <sequenceFlow id="flow1" sourceRef="startEvent" targetRef="scriptTask" />
    <scriptTask id="scriptTask" scriptFormat="groovy">
      <extensionElements>
        <camunda:inputOutput>
          <camunda:inputParameter name="friend">

            <!-- script as input parameter -->
            <camunda:script scriptFormat="groovy">
              friends = ["Fritz", "Heinz", "Horst", "Klaus"]
              friends[new Random().nextInt(friends.size())]
            </camunda:script>

          </camunda:inputParameter>
        </camunda:inputOutput>
      </extensionElements>

      <!-- script as script task -->
      <script>
        println "Hello $friend! Welcome to our casino"
      </script>

    </scriptTask>
    <sequenceFlow id="flow2" sourceRef="scriptTask" targetRef="gateway" />
    <exclusiveGateway id="gateway" name="Dice">
      <extensionElements>
        <camunda:executionListener event="start">

          <!-- script as execution listener -->
          <camunda:script scriptFormat="groovy">
            aNumber = new Random().nextInt(6) + 1
            println "$aNumber was diced"
            execution.setVariable('aNumber', aNumber)
          </camunda:script>

        </camunda:executionListener>
      </extensionElements>
    </exclusiveGateway>
    <sequenceFlow sourceRef="gateway" targetRef="userTask1">

      <!-- script as sequence flow condition -->
      <conditionExpression xsi:type="tFormalExpression" language="groovy">
        <![CDATA[
          aNumber < 4
        ]]>
      </conditionExpression>

    </sequenceFlow>
    <userTask id="userTask1" name="Less than 4">
      <extensionElements>
        <camunda:taskListener event="create">

          <!-- script as task listener -->
          <camunda:script scriptFormat="groovy">
            println "User task '$task.name' was $task.eventName"
          </camunda:script>

        </camunda:taskListener>
      </extensionElements>
    </userTask>
    <sequenceFlow sourceRef="gateway" targetRef="userTask2">

      <!-- script as sequence flow condition -->
      <conditionExpression xsi:type="tFormalExpression" language="groovy">
        aNumber > 3
      </conditionExpression>

    </sequenceFlow>
    <userTask id="userTask2" name="Greater than 3">
      <extensionElements>
        <camunda:taskListener event="create">

          <!-- script as task listener -->
          <camunda:script scriptFormat="groovy">
            println "User task '$task.name' was $task.eventName"
          </camunda:script>

        </camunda:taskListener>
      </extensionElements>
    </userTask>
  </process>

  <!-- bpmn di omitted -->
</definitions>

scriptTask.xml