Creating Java Service Task dynamically

mashrur

We would like to give facility to our application users to create activiti workflow. To achieve this, I am trying to use code from the below article:
http://stacktrace.be/blog/2013/03/dynamic-process-creation-and-deployment-in-100-lines/
or,
https://github.com/sunnydyal/workflow/blob/master/workflow/src/test/java/com/netsmartz/workflow/DynamicActivitiProcessTest.java


But it does not show how to create a Java ServiceTask within the process. I tried with this:

        protected FlowElement createServiceTask(String name){
      ServiceTask stask = new ServiceTask();
      stask.setId("1");
      stask.setName(name);
      stask.setImplementation("activitiTest.PrintVariables");
      return stask;
   }

And, edited the existing code to add the service task ("sampleservice") as below:

                process.addFlowElement(createStartEvent());
      process.addFlowElement(createUserTask("task1", "First task", "fred"));
      process.addFlowElement(createUserTask("task2", "Second task", "john"));
      process.addFlowElement(createServiceTask("sampleservice"));
      process.addFlowElement(createEndEvent());

      process.addFlowElement(createSequenceFlow("start", "task1"));
      process.addFlowElement(createSequenceFlow("task1", "task2"));
      process.addFlowElement(createSequenceFlow("task2", "sampleservice"));
      process.addFlowElement(createSequenceFlow("sampleservice", "end"));

But, I am getting this error:
java.lang.NullPointerException
   at org.activiti.bpmn.BpmnAutoLayout.generateSequenceFlowDiagramInterchangeElements(BpmnAutoLayout.java:315)
   at org.activiti.bpmn.BpmnAutoLayout.generateDiagramInterchangeElements(BpmnAutoLayout.java:272)
   at org.activiti.bpmn.BpmnAutoLayout.layout(BpmnAutoLayout.java:139)
   at org.activiti.bpmn.BpmnAutoLayout.execute(BpmnAutoLayout.java:87)
   at activitiTest.DynamicFlowCreation.testDynamicDeploy(DynamicFlowCreation.java:53)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
   at java.lang.reflect.Method.invoke(Unknown Source)
   at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
   at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
   at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
   at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
   at org.activiti.engine.test.ActivitiRule$1.evaluate(ActivitiRule.java:124)
   at org.junit.rules.RunRules.evaluate(RunRules.java:20)
   at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
   at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
   at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
   at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
   at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
   at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
   at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
   at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
   at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
   at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
   at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Any suggestion?
Thanks in advance
Mashrur

mashrur

Got it. I had to set implementationType :
                String implementationType = ImplementationType.IMPLEMENTATION_TYPE_DELEGATEEXPRESSION;
  stask.setImplementationType(implementationType );