topic Re: Parsing the process definition in Alfresco Archive

Parsing the process definition

frauke — Tue, 05 Oct 2010 14:21:38 GMT

Hello everybody,is it possible to parse the process definition before the process has been started?We like to get some information about the tasks before starting the process.Frauke

Re: Parsing the process definition

jbarrez — Wed, 06 Oct 2010 08:40:11 GMT

That's currently not possible (at least not without casting: you could do it by obtaining a ProcessDefinition through the processDefinitionQuery),
but we have had several request for this so we are currently thinking about incorporating this in the API.

Re: Parsing the process definition

frauke — Wed, 06 Oct 2010 09:33:02 GMT

Ok, can get the process definition:


ProcessDefinition p = processEngine.getRepositoryService()
            .createProcessDefinitionQuery()
            .key(processName).singleResult()

Correct? But what should I cast to? And then how can I get to the definition itself?
Even with the debugger I could not see something helpful in the ProcessDefinition.
Please, could you give me some hints how to proceed, so I don't have to wait for the next release?

Re: Parsing the process definition

jbarrez — Wed, 06 Oct 2010 12:06:22 GMT

It;s very low-level PVM code, but this should do it:

cast to ProcessDefinitionImpl. This has an getInitial() method which returns an ActivityImpl.
This ActivityImpl has outgoingTransitions that can be followed to its destinatiins (again ActivityImpl).

But as you would agree, this isnt very pretty to look at 😉

Re: Parsing the process definition

frauke — Wed, 06 Oct 2010 12:21:43 GMT

Oh, it looks pretty enough to me … if it would work like that.
But the getInitial() returns null. :cry:

Re: Parsing the process definition

iravanchi — Thu, 07 Oct 2010 07:19:14 GMT

This issue is what I ran into several days ago, and there's another thread about it:
http://forums.activiti.org/en/viewtopic.php?f=3&t=288

It is null because the process definition is not parsed at that point.
When you start a process, Activiti looks up the cache, and if the process is not in the cache it loads it, parses it (from the bytes of deployment) and puts it into the cache.

Your issue comes up because the definition is not parsed until it is needed for execution by PVM. There will be API for loading it, see here:
http://jira.codehaus.org/browse/ACT-172

Meanwhile, here's a very ugly hack:
If you start the process once, it should be placed in the cache alright. So if you can somehow start a fake instance of the process, that should work for you (I guess).

I'm waiting for my access to be granted on Activiti source code. I can fix this issue quickly if so, and let you know.

-Hamed

Re: Parsing the process definition

falko_menge — Wed, 13 Oct 2010 21:50:52 GMT

To elaborate a bit more on that ugly hack:
The ProcessInstance returned by the startProcessInstanceBy* methods of the RuntimeService contains an introspectable ProcessDefinitionEntity. So either you keep that ProcessDefinitionEntity in memory or you start a fake instance every time you need it.

Re: Parsing the process definition

frauke — Thu, 14 Oct 2010 06:32:22 GMT

Is is possible to start the fake process instance without the process doing something?
Usually if I start the process it starts modifying my system right away and I can't do that.

Re: Parsing the process definition

tombaeyens — Thu, 14 Oct 2010 10:35:52 GMT

method to inspect the process was added http://jira.codehaus.org/browse/ACT-242

Re: Parsing the process definition

iravanchi — Thu, 14 Oct 2010 14:09:27 GMT

ACT-172 is a related issue. You might want to mark it as resolved too.

Re: Parsing the process definition

jbarrez — Mon, 18 Oct 2010 08:39:43 GMT

Correct. I closed it. Thanks!

Re: Parsing the process definition

rmoskal — Thu, 17 Mar 2011 21:54:21 GMT

I still don't see the api function from ACT-242 in 5.3.

ReadOnlyProcessDefinition RepositoryService.getDeployedProcessDefinition(String);

I would like to introspect the structure of some of my workflows, what to do?

Re: Parsing the process definition

rmoskal — Thu, 17 Mar 2011 22:01:01 GMT

And a processquery from the runtime service doesn't return a ProcessInstance with the ProcessDefinition fields populated.

Re: Parsing the process definition

jbarrez — Mon, 21 Mar 2011 16:51:24 GMT

You will need to cast to RepositoryServiceImpl to see the method. It's not yet 100% as we would like it, hence the cast.

And a processquery from the runtime service doesn't return a ProcessInstance with the ProcessDefinition fields populated.

No, this is for performance reasons, as parsing the process definition is time-consuming and wouldnt service 80% of the typical use cases.
So you would need a second query to get the details.