Activiti event for process instance creation?

[cdeneux]

Hi all,

I try to inject dedicated processing on a process instance creation, completion and deletion (for example adding a log trace), with the following constraints:

• The processing must be applied on all my process definitions deployed
• The processing must not impact the process definition because it's a technical processing

I found a solution for process instance completion and deletion: adding event listeners on the events PROCESS_COMPLETED and PROCESS_CANCELLED.

But it seems to me that no event PROCESS_CREATED or PROCESS_INSTANCE_CREATED exists ? Can I use event ENTITY_CREATED or ACTIVITY_STARTED ? Or should I investigate another solution ? Or can I add a support of such an event ?

Note: the solution mentioned in [1] can not be applied in my use case because process definitions are impacted.

Thanks for your recommendations,

Regards,
Christophe DENEUX

[1] http://stackoverflow.com/questions/25428147/activiti-event-for-process-instance-creation

[trademak]

Hi,

You can listen to ENTITY_CREATED. That event is fired when a process instance is started.

Best regards,

[cdeneux]

Thanks Tijs,

Is event ENTITY CREATED fired only when a process instance is started ?

In the associated event listener, I try to get variables passed to [font=Courier]RuntimeService.startProcessInstanceById()[/font] used to create the process instance. But I'm not able to retrieve the process instance through a [font=Courier]ProcessInstanceQuery[/font], my query result [font=Courier]processResult[/font] is [font=Courier]null[/font]:
<code>
final ProcessInstanceQuery processQuery = event.getEngineServices().getRuntimeService()
        .createProcessInstanceQuery()
                .processInstanceId(processInstanceId)
                .includeProcessVariables();
final ProcessInstance processResult = processQuery.singleResult();
</code>

How can I retrieve the process instance created when receiving the event ENTITY_CREATED ?

Thanks for your help

Regards,
Christophe DENEUX

[cdeneux]

Hi all,

According to the current source code, it seems to me that a process instance is created through the method [font=Courier]org.activiti.engine.impl.cmd.StartProcessInstanceCmd.execute()[/font]:
<code>
   …
1 // Start the process instance
2 ExecutionEntity processInstance = processDefinition.createProcessInstance(businessKey);
3
4 // now set the variables passed into the start command
5 if (variables != null) {
6   processInstance.setVariables(variables);
7 }
8  
9 // now set processInstance name
10 if (processInstanceName != null) {
11   processInstance.setName(processInstanceName);
12 }
13
14 processInstance.start();
15
16 return processInstance;
</code>

The event ENTITY_CREATED is fired at line 1 by [font=Courier]processDefinition.createProcessInstance(businessKey)[/font], but variables are set into the process instance after the process instance creation.

After other investigations in source, the start of the process instance at line 14 performs the operation [font=Courier]org.activiti.engine.impl.pvm.runtime.AtomicOperation.PROCESS_START[/font] that is implemented by [font=Courier]org.activiti.engine.impl.pvm.runtime.AtomicOperationProcessStart[/font]. This implementation fires the event ENTITY_INITIALIZED.

Moreover, the events ENTITY_CREATED and ENTITY_INITIALIZED are not fired only for on a process instance creation. I receive them on an identify link add.
So, I must filter events in the event listener as following:
<code>
final ActivitiEntityWithVariablesEvent eventImpl = (ActivitiEntityWithVariablesEvent)event;
if (eventImpl.getEntity() instanceof ExecutionEntity) {
    …           
}
</code>

Is it correct ?

For performance reason and to avoid filtering, it seems to me that an event PROCESS_STARTED should be introduced and fired in the same location than the event ENTITY_INITIALIZED in [font=Courier]AtomicOperationProcessStart[/font]. What do you think ? If you are ok, I can contribute it.

Thanks for your help,

Regards,
Christophe DENEUX

[jbarrez]

I agree that a process start event would make a lot of sense. A contribution would certainly be appreciated!

[cdeneux]

Hi,

I've started a contribution [1] waiting to create a pull request. And I've just created the JIRA issue [2].

What do you think about a call activity with the new event ? I think that the event PROCESS_STARTED should be fired also when starting the new process instance created through the call activity.

Regards,
Christophe DENEUX

[1]: https://github.com/cdeneux/Activiti/tree/event_PROCESS_INSTANCE_STARTED
[2]: https://activiti.atlassian.net/browse/ACT-3994

[jbarrez]

> I think that the event PROCESS_STARTED should be fired also when starting the new process instance created through the call activity.

I agree. But if possible, would be good if that information could be contained in the event too.

[cdeneux]

I have added to the event the following information to track the process in which a call activity starts another process:

• process instance id of the nested process,
• process definition if of the nested process.

These attributes are set to null for a main process (not invoked through a call activity)

If you think that is right, I could create a pull request.

Regards,
Christophe DENEUX

[jbarrez]

Wouldn't it make more sense to have the parent information in there (instead of the nested)?

Feel free to push a Pull Request, we can surely discuss further there too, with some real code 🙂

[cdeneux]

Joram,

I've just pushed the pull request: https://github.com/Activiti/Activiti/pull/570.

You're right, the two attributes of the event mentioned below should be renamed (from 'nestedProcess…Id' to 'parentProcess…Id') . They hold the parent process instance identifiers for a nested process, or null for a main process.

–
Regards,
Christophe