topic Re: How to get listener? in Alfresco Archive

How to get listener?

afenske — Fri, 12 Apr 2013 08:09:05 GMT

Hello.I've got a problem. I have a business process and a client, which is written in Eclipse RCP. My client interacts with the business process through Activiti API.How can I determine the moment when there is a new task in the queue? In other words, I want to add a listener on the client to catch

Re: How to get listener?

pkromolowski — Fri, 12 Apr 2013 10:42:16 GMT

If using Activiti version prior to 5.12 you can register a BpmnParseListener like this:

configuration.getPreParseListeners().add(new MyBPMNPreParseListener());
before you call configuration.buildProcessEngine() method.

You can then register task listeners within your MyBPMNPreParseListener:


public void parseUserTask(Element elem, ScopeImpl scope, ActivityImpl activity)
{
      TaskDefinition definition = ((UserTaskActivityBehavior) activity.getActivityBehavior()).
      definition.addTaskListener(TaskListener.EVENTNAME_CREATE, new MyTaskListener()); // MyTaskListener implements org.activiti.engine.delegate.TaskListener
      …
}

In 5.12+ versions you should use the new BpmnParseHandler approach, wich basically gives you the same functionality (hovewever, you can't access the XML structure of a task - this will propably be available in 5.13 version).

Best regards,

Re: How to get listener?

afenske — Fri, 12 Apr 2013 14:49:42 GMT

Thank you, Przemek Kromolowski.

Re: How to get listener?

afenske — Mon, 22 Apr 2013 08:18:22 GMT

I encountered a problem. Suggested approach works well just when you do some actions within the same application where you created a listener. If you try to complete some action from another app, for example, activiti explorer, listener won't catch that moment.

Best regards,
Anton Fenske.

Re: How to get listener?

jbarrez — Mon, 22 Apr 2013 10:09:07 GMT

No, that is indeed correct. If you want to use it in Explorer, the process engine config must be updated + the relevant classes must be put on the classpath.

Re: How to get listener?

afenske — Mon, 22 Apr 2013 14:32:59 GMT

I don't understand.

Let me clarify the task.

I have the next problem. Imagine that you have an application A and another application B. They work with the same instance of some business process.

In A I created a listener and it works well when I do some steps of business process from A. But when I do some steps from B, A's listener doesn't catch any actions which have done from B.

Is it possible to let A's listener to react on actions which have happened in B?

Best regards,
Anton Fenske.

Re: How to get listener?

jbarrez — Wed, 24 Apr 2013 07:14:44 GMT

> Is it possible to let A's listener to react on actions which have happened in B?

Clarification was not needed, I did understand what you mean. And my response stays the same: if you want the listeners to fire on both A and B you need to configure both A and B to have the same configuration: same process engine config + same listener classes.

Re: How to get listener?

afenske — Thu, 25 Apr 2013 13:12:09 GMT

I tried to do it. I launched two the same apps, but I recognized that listener worked just from the process which I had used before event was happened and listener in another app didn't react to that event.

Re: How to get listener?

jbarrez — Tue, 30 Apr 2013 08:20:46 GMT

I don't really get what you try to do. I read your original question and it seems to me you just need to fire an event on the task creation to some queue (outside of Activiti) that then acts upon that. And the way to do it, is exactly how the first response (from Przemek) describes it.

> Is it possible to let A's listener to react on actions which have happened in B?

Can you clarify that with some BPMN? Cause I really don't get what exactly you try to do.

Re: How to get listener?

afenske — Mon, 06 May 2013 08:07:51 GMT

Ok. We have two user tasks. Kermit uses the first one to select a user who will complete the second task. The problem is to fire some event, which will be signal about a new task creation, from those client who will be selected by kermit in the first task.
Could you give an example of a necessary task handler and an activiti-config.xml file?
Bpmn file is in the attacnment.

Re: How to get listener?

frederikherema1 — Mon, 06 May 2013 09:51:38 GMT

Judging from your process, you already have a task-listener attached to the task (ru.cniieisu.dit.activiti.Task2Listener). From inside that class, you'll get a DelegateTask pointer which offers you everything you need to signal the external system. It's just a matter of hooking/wiring your services (which need to be signaled about task creation/completion) in the JavaDelegate implementation.

Re: How to get listener?

afenske — Mon, 06 May 2013 12:08:46 GMT

Yes, but it is true just for a task, which has that listener.
But If I want to create universal listener for all tasks, what should I do?
I think to set one listener for all tasks isn't a good idea.

Re: How to get listener?

frederikherema1 — Wed, 08 May 2013 07:19:26 GMT

You can use a ParseHandler to add listeners to all tasks when they are parsed to be used in the engine. This way, your BPMN2.0 doesn't contain any listener code, the listeners are added transparently to all processed deployed.

Re: How to get listener?

odemwingie — Wed, 08 May 2013 21:26:23 GMT

Guys, it's just running in circle. Your advices work only at one PC where we create the new process (Anton has written it in his 3rd and 4th posts), but at the another PC with the same app (surely the configuration is identical with the first one) doesn't catch new process instances - and this is the problem we try to solve!

Re: How to get listener?

tcheekva — Thu, 09 May 2013 12:02:07 GMT

Sounds like you have 2 engines configured one for each app. You will have to come up with your own mechanism to communicate between them. The engines do not talk to each other. The listeners only have access to events in the engine they are running in..

Re: How to get listener?

odemwingie — Sun, 12 May 2013 19:27:26 GMT

and is there any examples how to do it somewhere?

Re: How to get listener?

frederikherema1 — Mon, 13 May 2013 09:12:07 GMT

Indeed, the 2 process-engines don't communicate with each other. The engine which starts the process will receive the event. The other won't. You'll have to use an external queue, which the task is added to from one of the 2 engines. Than, in the right application, the queue is read out and reacted upon. There is no "general" approach for this. Either use a custom rolled solution or use a messaging-queue product.