topic Re: Parallel gateway does not activate in Alfresco Archive

Parallel gateway does not activate

mahavirj — Sun, 20 Feb 2011 02:55:02 GMT

Since <inclusiveGateway> is not supported as yet, a combination of divergent parallelGateway + exclusiveGateway has to be used to get that functionality. In one specific scenario, however, a convergent parallelGateway does not activate. I could reproduce this issue by adding this scenario to t

Re: Parallel gateway does not activate

jbarrez — Mon, 21 Feb 2011 08:12:23 GMT

I'm not quite following what you are trying to acomplish here. Could you provide a visual diagram to make it more clear?

Re: Parallel gateway does not activate

mahavirj — Mon, 21 Feb 2011 14:47:16 GMT

Here's the subprocess flow. PG = parallel gateway, EG = exclusive gateway. The issue is PG2 does not activate

[attachment=0]Update External Systems.jpg[/attachment]

Re: Parallel gateway does not activate

jbarrez — Mon, 21 Feb 2011 14:54:52 GMT

The parallelGW will activate only if the number of incoming executions is equal to the number of incoming sequence flow.

In this case, you have 4 incoming sequence flow, but PG2 can maximum receive 3 executions in the best case (if I'm not mistaken).
So the parallel gateway will indeed never activate. Placing a converging exclusive gateway in between should do the trick, I think.

Re: Parallel gateway does not activate

mahavirj — Mon, 21 Feb 2011 15:45:51 GMT

Yes, if I change PG2 to an exclusive gateway, say EGX, it works. However, according to BPMN2, a converging exclusive gateway does not synchronize flows, which means in this case it will always get triggered since task1 is always being completed regardless of what happens in EG2. i.e. I don't want the subprocess to end just based on task1 completion.

So, if I leave task1->PG2 flow untouched and converge the other 4 flows to EGX and connect EGX to PG2 it works conditionally.

i.e. if EG1 evaluates to true EG1->EGX->PG2 does not work. But, if EG1 evaluates to false and EG2 evaluates to true, it works since the number of flows = number of executions @ PG2.

Re: Parallel gateway does not activate

mahavirj — Mon, 21 Feb 2011 19:38:24 GMT

Got it to work by adding a some 'do nothing' servicetasks when there is no need for an execution instance for e.g. between eg1->egx->pg2. This should not be necessary though. Would it not be possible to count the execution instance of task2 when applying that rule (#of flows=#of executions) for activating paralell gateway?

Re: Parallel gateway does not activate

jbarrez — Wed, 23 Feb 2011 09:14:54 GMT

Could you attach your process xml, because it is hard to follow.

Would it not be possible to count the execution instance of task2 when applying that rule (#of flows=#of executions) for activating paralell gateway

I'm not following here, why would task2 have influence on the count of the parallel gateway?

Re: Parallel gateway does not activate

mahavirj — Wed, 23 Feb 2011 16:01:57 GMT

In the diagram, there are 5 inflows to parallel gateway PG2. Three of them have executions (task1, task4, task3) and two don't (EG1-to-PG2 and EG2-to-PG2). Since the number of executions != number of flow,PG2 does not activate.

But, this is a valid requirement i.e. there is really nothing to do in EG1-to-PG2 and EG2-to-PG2. Changing PG2 to an exclusive gateway will not help because completion of task1 will always activate it i.e. it wont wait for the result of the other 4 flows

So, the only way out is leave PG2 as a parallel gateway and define a do nothing <servicetask> for each of the EG1-to-PG2 and EG2-to-PG2 flows. This will make the number of executions == number of flows in all cases and will activate PG2 correctly.

However, these do-nothing <servicetask> are unnecessary. It should just be a matter of counting the # of executions…that's why i was suggesting to use task2 execution-id as the execution token for the flows which do not have an execution (in this case EG1-to-PG2 and EG2-to-PG2) i.e task2 is the preceding task for those do-nothing flows

The subprocess XML was in the first post. However, let me know if you still need the entire process xml and the unit tests