topic Re: Signal/Cancel running process in Alfresco Archive

Signal/Cancel running process

mbonato — Mon, 18 Aug 2014 09:15:37 GMT

I'm trying to find a good/suitable process design for a 'cancelable' process that involves some asynchronous tasks and a message receive task. The process may be simplified to the process shown in the following figure. [img]http://snag.gy/BBBfQ.jpg[/img]What makes things complicated is concurrency.

Re: Signal/Cancel running process

jbarrez — Tue, 19 Aug 2014 11:04:25 GMT

Besides cluster-wide locks, i think there is no other decent solution technically.
Note that a cluster-wide lock is not as scary as you might think: it might be just an entry in a database table where one cluster node has to 'take ownership' of before it can execute the process instance.

Solution 2 sounds like it will work, but it's a lot of work to get right I think.

Re: Signal/Cancel running process

mbonato — Tue, 19 Aug 2014 11:23:30 GMT

Thank you for your quick response!

I already thought about using database based locks, but I'm not sure how to handle asynchronous job execution. How can I make the job acquisition thread respect these locks?

Re: Signal/Cancel running process

jbarrez — Wed, 20 Aug 2014 14:51:39 GMT

Hmm, in that case , in your service task, you'd need to use another transaction probably (ie also another transaction manager) to do those locking.

Another option which migh be easier development wise (but a little bit heavier deployment-wise) is to use distributed locks like for example used in Hazelcast (and alternatives)