Handle Human Task with custom HumanTaskHandler

[lauradp]

Hello everybody,

I was trying to run a human task with a custom handler, but my handler doesn't work.

Can anyone help me?

Laura

public class TestHumanTask {

          public static final void main(String[] args) throws Exception {

                    startUp();

                    // load up the knowledge base

                    KnowledgeBase kbase = readKnowledgeBase();

                    StatefulKnowledgeSession ksession = JBPMHelper.newStatefulKnowledgeSession(kbase);

                    //StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();

                    CommandHumanTaskHandler handler = new CommandHumanTaskHandler();

                    ksession.getWorkItemManager().registerWorkItemHandler("RunAction", handler);

                    //params

                    // start a new process instance

                    ksession.startProcess("com.sample.bpmn.hello");

                    System.out.println("Process started ...");

          }

          private static KnowledgeBase readKnowledgeBase() throws Exception {

                    KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();

                    kbuilder.add(ResourceFactory.newClassPathResource("sample.bpmn"), ResourceType.BPMN2);

                    return kbuilder.newKnowledgeBase();

          }

          private static void startUp() {

                    JBPMHelper.startH2Server();

                    JBPMHelper.setupDataSource();

                    // please comment this line if you already have the task service running,

                    // for example when running the jbpm-installer

                    JBPMHelper.startTaskService();

          }

}

public class CommandHumanTaskHandler extends HumanTaskHandler{

          private static final long serialVersionUID = 1L;

          public CommandHumanTaskHandler () {

                    super();

                    System.out.println("NEW");

          }

          public void executeWorkItem(WorkItem workItem, WorkItemManager manager) {

                    //super.executeWorkItem(workItem, manager);

                    System.out.println("executing....");

                    manager.completeWorkItem(workItem.getId(), null);

          }

          public void complete(WorkItem workItem,  Map<String,Object> results){

                    System.out.println("Completing...");

                    //super.complete(workItem, results);

          }

          @Override

          public void abortWorkItem(WorkItem arg0, WorkItemManager arg1) {

                    // TODO Auto-generated method stub

                    System.out.println("Aborting....");

          }

}

[salaboy21]

Hi Laura,

What are you trying to achieve with it?

Can you explains us a little bit more about your goal in extending the HumanTaskHandler?

Cheers

[lauradp]

Hi Mauricio,

thanks for your answer!

I need to start an external command as task of the HT.

In my example above I'm just trying to print a string, to ensure that on pressing the [Start] button (in the Human Task view) the executeWorkItem method is reached, but the String is NOT printed.

[salaboy21]

I still don't understand why you want to execute a command on an HT but, if you want to achieve that you should do:

ksession.getWorkItemManager().registerWorkItemHandler("Human Task", handler);

That will print the string that you want.

Cheers

[lauradp]

Thanks for your answer.

My goal is to do "something" when the [Start] button in the "HumanTask" view is pressed.

Now all my strings are printed as the prosess start, I thought that the executeWorkItem method was reached on pressing the [Start] button, am I wrong?

[salaboy21]

I'm not sure to understand what you mean by "Start Button" do you have an application that starts the task?

No the executeWorkItem method is executed when the task is created.

If you want to do something before or after starting a task you will need to do that before or after calling taskClient.start(taskId, user);

Cheers

[lauradp]

I'm using Eclipse to test the process.

My goal is to do something (e.g. print "hello World") as soon as I start the Human task

[salaboy21]

I don't know how the eclipse plugin work, but I know for sure that the Start Button is calling the TaskClient.start() method.

At this point I must ask, if you really need to use the eclipse plugin? you will usually will need to build your own app for your end users right?

When you build your own app you will see that you will have those hook points.

If you want to see an example about this you can take a look at here:

https://github.com/Salaboy/jBPM5-Developer-Guide/tree/master/chapter_07/jBPM5-HumanTaskUI-Swing

That project is a simple Human Task client built using Swing, it also has a start button, and there you can go and add your logic. But once again, take this as an example, because you will probably need to build your own app for that kind of things.

Cheers

[lauradp]

I'm using Eclipse because I'm trying to make the process work! In a future I'll use the HumanTask API to manage process execution.

I have another question, why should I use the "Human task" string in the registerWorkItemHandler method, instead of "RunAction" (i.e. my Human task's name)?

ksession.getWorkItemManager().registerWorkItemHandler("Human Task", handler);

[lauradp]

Maybe my question was not understandable enough! My will is to let Human Task run some java code when they are started! How can I reach this goal???