topic Issue querying for Signal in Alfresco Forum

Issue querying for Signal

jpgouin — Thu, 27 Jul 2017 12:10:20 GMT

Hi,I have a problem regarding the query of signal.I'm trying to use signalEventReceived(signalName,executionId) to trigger a boundary signal. However it does not work, it says that Execution xx has not subscribed to a signal event with name xx.And when I query for the active execution , there is no

Re: Issue querying for Signal

cjose — Tue, 01 Aug 2017 04:32:33 GMT

runtimeService.createExecutionQuery().signalEventSubscriptionName(signalName) is the correct way to query for active executions..however it looks strange to have an signal boundary event on a sync service task. May be I didn't understand your use case here... Are you expecting to send a message in the service task and want to wait for a signal in the same task? Do you have any unit tests that I can run to reproduce the issue on my end?

Ciju

Re: Issue querying for Signal

jpgouin — Tue, 01 Aug 2017 12:43:51 GMT

In this case, the synchronous service task is a call to a camel route , and the route can terminate by sending a signal and therefore trigger the boundary event to perform a custom action defined in the script task . Or the camel route can end nominally and the workflow continue.

I join a test case that illustrate the issue.

The thing to do is to put a breakpoint in the sendSignal method , and you'll see that the execution resulting of the query is null.

And the execution result of the query only on the processInstanceId contain the scopeExecution object that contains the boundarySignalDefinition of the signal.

Thanks ,

Jean-Philippe

Re: Issue querying for Signal

cjose — Tue, 01 Aug 2017 15:59:55 GMT

Hi Jean-Philippe,

Thank you for the sample process and test case. From a quick look at the xml and your use case, it makes sense to follow the async pattern as explained here. The query apis are basically querying the database and since your service task is configured as "sync", the entry will not be in the database until the process reaches the next wait state...This is probably why your execution query is returning null.

I'll check out your test case and example in detail when I get a few minutes.

Ciju

Re: Issue querying for Signal

jpgouin — Wed, 02 Aug 2017 09:37:33 GMT

Hi Ciju,

Thanks for your answer, I tried with the activiti:async="true" on the service task but still the same result.

I could use other way to achieve what I want , but I just want to prove if it's possible to trigger a boundary event from a camel route.

Since the first script task is async , I don't think this is an issue about async pattern.

Jean-Philippe

Re: Issue querying for Signal

cjose — Thu, 03 Aug 2017 04:08:35 GMT

Hi,

I had a detailed look at your post today.
I don't think timer, event and signal boundary events work on script/services/camel tasks in Activiti...not sure if it is by design or a defect! Feel free to raise an issue or even a contribution (which would be great!) assuming it is valid as per BPMN 2.0 spec. This is probably the main reason why you not able to trigger a signal attached to your Camel task.

Regarding the async setting I mentioned, assume that Activiti supported boundary signals/messages on Camel task, then I would expect those message/signal subscription to work only after the activity it is attached to is persisted to database (which is essentially controlled by the setting of async flag explained at https://activiti.github.io/userguide/5.19.0/index.html#asyncContinuations).

Is your camel task a very long running task? If that is the only reason for a boundary event, you can achieve that using a Camel + Receive Task pattern as explained in the user guide https://activiti.github.io/userguide/5.19.0/index.html#bpmnCamelTask.

A normal Camel + Receive Task pattern that is used in the following test cases in Activiti are working fine
https://github.com/Activiti/Activiti/blob/5.x/modules/activiti-camel/src/test/java/org/activiti/camel/AsyncPingTest.java
https://github.com/Activiti/Activiti/blob/5.x/modules/activiti-camel/src/test/java/org/activiti/camel/AsyncProcessTest.java
With the above pattern, I was hoping that I can include a boundary signal on the receive task if I want to terminate it using external signals...However there appears an issue when there are boundary events on those receive tasks. Looks like the Camel Behavior in Activiti is not completing the boundary events when Receive Tasks are completed...

Feel free to raise an issue on this in Activiti. Btw, until this issue is fixed, you might be able to achieve similar external signaling + camel signaling functionality by altering the process model a bit. Please find attached the project I used to test these behaviors. Hope this helps!