Exception Handling of Asynchronous Processes

As we transition to the new Hyland Community, some post links may be temporarily disrupted as we finalize redirects. We apologize for the inconvenience and are working to resolve this as quickly as possible. Details.

flavio_donze

Hello

After the discussion here http://forums.activiti.org/en/viewtopic.php?f=6&t=6334 about transaction deadlocks, I ended up setting my callActivity activiti:async="true".
This solved my deadlock problem, but now I'm facing the problem of handling exceptions.

The workflow that caused the deadlocks, does not have any user interaction, it consists of a bunch of serviceTasks.
Before adding the async="true", in case one of the serviceTasks threw an exception it was caught by the client and displayed in a message box.
The whole transaction was rollbacked and no workflow was stored in the database.
Using the async="true", the client does not get notified if something went wrong, since the workflow is running asynchronous on the server.
d
I found this in the documentation: http://activiti.org/userguide/index.html#serviceTaskExceptionHandling
But this won't fit my usecase, I dont want to have an outgoing "exception" sequenceFlow for every service task, plus it won't work because the transaction is marked for rollback.

This is one of my service tasks, for all service tasks I use my own com.softmodeler.workflow.OSGiLookup.
Right now I catch the exception in the implemented JavaDelegate.execute(DelegateExecution execution), at this point the transaction is already marked for rollback.
I can not redirect the process since it will have no effekt after the rollback, so right now I'm creating and sending an error mail to the initiator of the workflow.
As I mentioned earlier, before the workflow was asynchronous, the exception was directly displayed to the user.

      <serviceTask id="storeRepository" activiti:class="com.softmodeler.workflow.OSGiLookup">
         <extensionElements>
             <activiti:field name="serviceName" expression="com.softmodeler.service.IRepositoryService"/>
             <activiti:field name="methodName" stringValue="storeProductiveObject"/>
             <activiti:field name="objectId" expression="${objectId}"/>
             <activiti:field name="param1" expression="${version}"/>
         </extensionElements>
      </serviceTask>
‍‍‍‍‍‍‍‍‍‍

So I was wondering maybe there is a "standard" way to handle this?
Maybe an exception or fail listener on the overall workflow.
How do other people handle exceptions in asynchronous workflows?

Also now I get three mails, since the job executor tries three times to execute the workflow.
Is it possible to disable this behaviour?

greets
Flavio

jbarrez

The problem is that you don't really know when the execution will actually happen.
If the load is high, it might even take a while before it is picked up by the job executor.

I think you need to ask yourself what would be the wanted behavior:
- Do you want to show it in the UI directly? If so, we will have to dig deeper in why the deadlock happens
- Is email sending enough?
- Do you want to create a dedicated UI for failed processes?

Also now I get three mails, since the job executor tries three times to execute the workflow.
Is it possible to disable this behaviour?

Yes: by default there is a retry interceptor configured when you execute any API call (and thus a Command).
You can remove this interceptor, change or tweak it. Or add your own.

Similarly you could add your own interceptor that does something with the exception that happens during process execution.
That way you can catch it (even when its done async) and do something accordingly.