topic Re: Signal not received by engine in Alfresco Archive

Signal not received by engine

andrey_nikolov — Mon, 29 Aug 2016 06:37:46 GMT

I am trying to implement a signal within the process instance to receive some data and then continue the execution with Activiti 5.21.The process definition defines the signal under definitions element. <signal id="Process_Signal" name="Process Signal" activiti:scope="processInstance"/>The c

Re: Signal not received by engine

andrey_nikolov — Mon, 29 Aug 2016 21:33:43 GMT

I have observed that sending a signal with name and execution ID does NOT work.
<code>
runtimeService.signalEventReceived("Process Signal", 12, VariablesMap)
</code>

However, sending the signal with execution ID only works.
<code>
runtimeService.signal(12, VariablesMap)
</code>

What is the difference between 'signal' and 'signalEventReceived' API? Could it be a bug or broken functionality in Activiti 5.21?

Re: Signal not received by engine

andrey_nikolov — Mon, 29 Aug 2016 21:36:56 GMT

The process definition defines the signal under definitions element.
<code>
<signal id="Process_Signal" name="Process Signal" activiti:scope="processInstance"/>
</code>
The catch node is defined under process element.
<code>
<intermediateCatchEvent id="Receive_Vacation_Balance" name="Receive Vacation Balance">
<signalEventDefinition signalRef="Process_Signal"/>
</intermediateCatchEvent>
</code>

Re: Signal not received by engine

andrey_nikolov — Tue, 30 Aug 2016 19:54:33 GMT

Please advise: what is the difference between 'signal' and 'signalEventReceived' API?

Is there an corresponding API to allow raising a signal by name? Perhaps something like
<code>
signal(signalName, execitionId, variablesMap)
</code>
We need to pass a signal to the engine and specify its name, so that within Activiti Listener we can distinguish which signal has been caught.

Re: Signal not received by engine

martin_grofcik — Wed, 31 Aug 2016 06:41:00 GMT

Hi Andrey,


  /**
   * Notifies the process engine that a signal event of name 'signalName' has been received. This method delivers the signal to all executions waiting on the signal.
   * <p/>
   * 
   * <strong>NOTE:</strong> The waiting executions are notified synchronously.
   * 
   * @param signalName
   *          the name of the signal event
   */
  void signalEventReceived(String signalName);


  /**
   * Sends an external trigger to an activity instance that is waiting inside
   * the given execution.
   * 
   * @param executionId
   *          id of execution to signal, cannot be null.
   * @throws ActivitiObjectNotFoundException
   *           when no execution is found for the given executionId.
   */
  void signal(String executionId);

The difference is that signal(String executionId) triggers execution. signalEventReceived(String signalName) sends a signal. It means that when some execution waits on the signal, signal is received and waiting execution is triggered.
You can create jUnit test to reproduce your issue.
https://forums.activiti.org/content/sticky-how-write-unit-test

Regards
Martin

Re: Signal not received by engine

andrey_nikolov — Wed, 31 Aug 2016 20:22:32 GMT

Hi Martin,

Thank you for your response!

Based on the API description, 'signalEventReceived' provides exactly the functionality we need: programmatically send a signal to Activiti engine.
<code>
Notifies the process engine that a signal event of name 'signalName' has been received. This method delivers the signal to all executions waiting on the signal. The waiting executions are notified synchronously.
</code>

The problem we have is that the signal is NOT actually caught by the engine and the process instance remains stuck at the 'intermediateCatchEvent'.

How could we check if the signal is received by the engine and properly correlated to the active instance? Do we need any special engine configuration to enable signal processing?

Re: Signal not received by engine

martin_grofcik — Thu, 01 Sep 2016 05:37:39 GMT

Hi Andrey,

As I said, create jUnit test
(https://forums.activiti.org/content/sticky-how-write-unit-test) and add link to your git hub fork. Then it will be easy to solve something.

Regards
Martin

Re: Signal not received by engine

martin_grofcik — Thu, 01 Sep 2016 05:40:04 GMT

Andrey,

You can have a look on
org.activiti.engine.test.bpmn.event.signal.SignalEventTest#testSignalCatchIntermediate
in activiti source - working signals example.

Regards
Martin