topic Re: Problems adding TaskListener from ParseHandler in Alfresco Archive

Problems adding TaskListener from ParseHandler

felipe1 — Wed, 27 Nov 2013 21:20:00 GMT

I'm trying to add custom a TaskListener to every UserTask declared in my processes.I have looked at this bit of the documentation (http://www.activiti.org/userguide/#advanced_parseHandlers) to get me started.I have also found this example of Handler that insert a custom handler to UserTasks - https:

Re: Problems adding TaskListener from ParseHandler

trademak — Thu, 28 Nov 2013 10:54:12 GMT

Could you create a unit test showing the issue?

Thanks,

Re: Problems adding TaskListener from ParseHandler

felipe1 — Thu, 28 Nov 2013 12:08:20 GMT

I'm attaching a unit test and supporting files. The test does not have any asserts, so it won't fail, but analyzing the console outputs will help you understand what is happening.

Re: Problems adding TaskListener from ParseHandler

felipe1 — Thu, 28 Nov 2013 12:43:18 GMT

Update:

- I have changed the activiti configuration file. I used "postBpmnParseHandlers" instead of "preBpmnParseHandlers", now the listener is added to all user tasks as expected.

I'm still facing an issue though. My TaskListener uses injected resources,

<code>
@Named
public class NotificaTarefaCriadaActiviti implements TaskListener {
@Inject
private Event<EventoCriacaoTarefa> evento; // null

@Inject
private ProcessEngine processEngine; // null
}
</code>

so if I simply instantiate a listener and add it to the task definition, the injected resources will resolve to null:

<code>
taskDefinition.addTaskListener(TaskListener.EVENTNAME_CREATE, new NotificaTarefaCriadaActiviti() );
</code>

I have tried to inject a listener from the ParseHandler, but that also resolved to null:

<code>
public class ParseHandlerCriaTarefaListener implements BpmnParseHandler {
@Inject
private NotificaTarefaCriadaActiviti listener; //null

        …..
}
</code>

When I declare the listener from the process definition file, like so:

<code>
   <extensionElements>
    <activiti:taskListener
     event="create"
     delegateExpression="#{notificaTarefaCriadaActiviti}"></activiti:taskListener>
   </extensionElements>
</code>

The resources are injected correctly into the Listener.

Re: Problems adding TaskListener from ParseHandler

trademak — Thu, 28 Nov 2013 13:52:17 GMT

Thanks, please create a Maven project and make that available if that's possible.

Best regards,

Re: Problems adding TaskListener from ParseHandler

felipe1 — Fri, 29 Nov 2013 11:13:50 GMT

Ok Tijs, I'll prepare a simple project and get back to you.

Thanks again!

Re: Problems adding TaskListener from ParseHandler

felipe1 — Fri, 29 Nov 2013 12:11:40 GMT

I have created a very simple web project that reproduces exactly what I have reported so far:

https://github.com/felipe-gdr/activiti-parsehandler

I have shared it in GitHub.

Please let me know if you need anything else.

Thanks again 🙂

Re: Problems adding TaskListener from ParseHandler

trademak — Fri, 29 Nov 2013 13:14:39 GMT

Thanks for sharing the source code.
The problem is that the @Inject doesn't work with a parse handler.
The parse handlers are instantiated by the Activiti Engine with the default constructor.

Best regards,

Re: Problems adding TaskListener from ParseHandler

felipe1 — Fri, 29 Nov 2013 16:07:01 GMT

Right, can you help me think of a workaround for my problem?

- I need to inject resources in my TaskListener (specifically a ProcessEngine instance and a Event instance)
- The TaskListener has to be added through a ParseHandler

Re: Problems adding TaskListener from ParseHandler

frederikherema1 — Thu, 05 Dec 2013 09:37:36 GMT

Tasklistener instances you create, in your parse-handler, are not aware of @Inject annotations. You should locate the needed resources in the ParseHandler yourself from the container you're in and set them on the listener instance… Or get an instance that is injected from the container.

Re: Problems adding TaskListener from ParseHandler

felipe1 — Thu, 05 Dec 2013 17:50:06 GMT

How can I locate the resources myself?

I'm sorry, I think I'm missing some concepts, but I cannot think of a way to achieve what you've suggested.

Here is my updated ParseHandler:


public class MyParseHandler implements BpmnParseHandler {
 @Inject
 private MyListener listener; // What should I put here to "manually inject" an instance of MyListener?
 
 @Override
 public Collection<Class<? extends BaseElement>> getHandledTypes() {
  List<Class<? extends BaseElement>> elements = new ArrayList<>();
  elements.add(UserTask.class);
  return elements;
 }

 @Override
 public void parse(BpmnParse bpmnParse, BaseElement element) { 
  String taskDefinitionKey = element.getId();
  
  TaskDefinition taskDefinition = ((ProcessDefinitionEntity) bpmnParse.getCurrentScope().getProcessDefinition()).getTaskDefinitions().get(
    taskDefinitionKey);

  if (taskDefinition != null) { 
   taskDefinition.addTaskListener(TaskListener.EVENTNAME_CREATE, listener); // listener is always null
  }
 }
}

Re: Problems adding TaskListener from ParseHandler

frederikherema1 — Fri, 06 Dec 2013 09:52:59 GMT

A few questions to help us understand and help you with fixing the issue:

- Are you using Spring or CDI as dependency container?
- If you're using Spring, make sure the Spring-version you're using uses the "JSR-299" annotations, which includes @Inject.
- If you're using spring, make sure you're using the SpringProcesEngineCOnfiguration (or the factory-bean) to have full spring-support
- In case You're using CDI, how do you configure your process-engine? If you're using the acidity.cfg.xml-file, consider using the CDI-support we have for activiti…

Re: Problems adding TaskListener from ParseHandler

felipe1 — Fri, 06 Dec 2013 10:44:34 GMT

Thanks for the help Frederik.

I'm using activiti CDI. Here is the content of the 'activiti.cfg.xml'.


<?xml version="1.0" encoding="UTF-8"?>
<beans
 xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans.xsd">

 <!– lookup the JTA-Transaction manager –>
 <bean
  id="transactionManager"
  class="org.springframework.jndi.JndiObjectFactoryBean">
  <property
   name="jndiName"
   value="java:jboss/TransactionManager"/>
  <property
   name="resourceRef"
   value="true" />
 </bean>

 <!– process engine configuration –>
 <bean
  id="processEngineConfiguration"
  class="org.activiti.cdi.CdiJtaProcessEngineConfiguration">
  <property
   name="dataSourceJndiName"
   value="java:/MyDS" />
  <property
   name="databaseType"
   value="mysql" />
  <property
   name="transactionManager"
   ref="transactionManager" />
  <property
   name="transactionsExternallyManaged"
   value="true" />
  <property
   name="databaseSchemaUpdate"
   value="true" />

   <property name="postBpmnParseHandlers">
    <list>
     <bean class="MyParseHandler" />
    </list>
   </property>
 </bean>
</beans>

Re: Problems adding TaskListener from ParseHandler

trademak — Fri, 06 Dec 2013 13:10:45 GMT

Please take a look at our activiti-cdi unit tests. Because there some examples are given where you don't need to inject the things you did, and still are able to send events etc. Also take a look at CdiEventSupportBpmnParseHandler and how it solves adding listeners for CDI usage.

Best regards,

Re: Problems adding TaskListener from ParseHandler

felipe1 — Fri, 06 Dec 2013 17:30:07 GMT

Great, I'll have a look them. Thanks for the help guys!

Re: Problems adding TaskListener from ParseHandler

felipe1 — Thu, 12 Dec 2013 23:23:09 GMT

Ok, you guys gave me great advices and pointed me in the right direction.

I replaced the @Inject with the following:

@Inject Event : BeanManagerLookup.getBeanManager().fireEvent();
@Inject ProcessEngine : ProcessEngines.getDefaultProcessEngine();

Now everything is working as I wanted.
thanks again!

Re: Problems adding TaskListener from ParseHandler

frederikherema1 — Fri, 13 Dec 2013 07:49:16 GMT

Thanks for posting back the solution. Great to see it working