topic Re: JTA and starting processes in Alfresco Archive

JTA and starting processes

tdtappe — Wed, 06 Mar 2013 10:54:26 GMT

I just started using Activiti. So my question(s) might be a bit "strange". Anyway…I am using Activiti embedded in my app in a JTA context. When I for instance create a new order I start an order process via API.The problem: the process starts right away without my order data having been committed ye

Re: JTA and starting processes

p4w3l — Thu, 07 Mar 2013 07:55:53 GMT

Why not commit tx then start a process with :

runtimeService.startProcessInstanceByKey( pKey, variables );
?

Re: JTA and starting processes

tdtappe — Thu, 07 Mar 2013 08:04:04 GMT

Because it runs in a JTA context. The "container" handles the transactions. And there might be more stuff to do after creating an order for instance. And it should be an "all or nothing" approach.

Re: JTA and starting processes

frederikherema1 — Thu, 07 Mar 2013 14:46:04 GMT

Activiti allows you to participate in a JTA-transaction, effectively not committing changes manually but relying on the container to do this. You'll have to use the JPAProcessEngineConfiguration instead of the normal one and hook in the transaction manager.

Re: JTA and starting processes

tdtappe — Thu, 07 Mar 2013 15:13:18 GMT

I know. And that's what I do already: the process engine is configured to use JTA. But the problem is that obviously the process starts immediately and reaches for instance a point in the process where it's necessary to get some information. This information (for a conditional flow) is "fetched" via a CDI function that in turn calls some REST function to get the desired information. But this REST call won't find the current data as the transaction that initiated all this isn't committed yet.

1) Container starts transaction
2) The application creates some data which is persisted (but of course not committed) to the database
3) The application then starts a process for this new data object
4) Container commits transaction

In the context of 3) a REST function call (initiated by the process) reaches the app which then tries to find the object in the database. But of course it isn't there yet => BANG

Re: JTA and starting processes

frederikherema1 — Thu, 07 Mar 2013 15:22:35 GMT

That's not an activiti-specific problem, that is a generic problem where you try to combine non-transactional calls (REST) with transactional things. A solution would be to make the ServiceTask that is performing the REST-call, asynchronous. This way, when the process is started and reaches that serviceTask, it will be persisted/comitted to the database and the job executor will execute the REST-operation asynchronously in a new transaction. Since the process is now persisted, the REST can access it.

Re: JTA and starting processes

tdtappe — Thu, 07 Mar 2013 15:36:39 GMT

Ok. So "async" could be a solution. But also in this case where I use a CDI object inside a sequence flow expression to get the information on how to proceed?
Or what else can I do?

Re: JTA and starting processes

frederikherema1 — Fri, 08 Mar 2013 09:36:33 GMT

Make sure the CDI-object in the sequence-flow is AFTER the async-tasks to make sure the REST-call won't fail due to uncommitted data…