topic Re: How to Handle Errors due to Database Timeouts in Alfresco Archive

How to Handle Errors due to Database Timeouts

zlatan316 — Thu, 07 May 2015 16:56:20 GMT

Hi,I have implemented a Java class which is able to run MS Project Server Reports. These are generated via an external webservice. The method call which retrieves the report can sometimes take a while to return the report instance. Because the transaction for the Process in Activiti has been open fo

Re: How to Handle Errors due to Database Timeouts

zlatan316 — Thu, 07 May 2015 16:59:34 GMT

Apologies for the format of the post, i cannot seem to edit it.

Re: How to Handle Errors due to Database Timeouts

pmsevestre — Sat, 09 May 2015 16:14:02 GMT

Hi,

In my environment I delegate such "long running" activities to a job scheduler. In the process definition I use "User Task" activities whenever I want to model a external job execution. The external job scheduler can then use the REST api or use a different Activiti engine instance (which points to the same DB, of course) in order to acquire jobs. Once the job is complete, you use the "Task Service" API to inform Activiti that the user task is complete, and your process instance moves on.

This approach has the following advantages:

* No database transaction timeout
* Better scalability
* The external task can be assigned to a a dedicated node, leading to better resource utilization.
* Easier recovery from system errors

The downsize is the extra complexity of running a separate job scheduler, but, IMO, I think it pays off.

Re: How to Handle Errors due to Database Timeouts

zlatan316 — Mon, 11 May 2015 08:38:48 GMT

Thanks for your response. I am planning on using the Scheduler functionality in the new 5.17 version of Activiti. But currently we have 5.14.

I actually just wanted to know that if we were to have a Service Task open for too long, can we catch the timeout error using an error event and drive the workflow to a different path?

Re: How to Handle Errors due to Database Timeouts

trademak — Wed, 13 May 2015 12:37:28 GMT

No, a service task is executed until it's ready. We don't allow for timeout events.

Best regards,

Re: How to Handle Errors due to Database Timeouts

zlatan316 — Thu, 14 May 2015 16:25:52 GMT

Thanks trademak. We will have to research the use of CAML to execute these long-running tasks outside of Activiti.