when you write a ServiceTask listener class, you need to call several services to synchronize at the same time, so you need to consider how to handle the synchronization failure.
my current idea is that one is to automatically retry after failure, and then run batch synchronization by timed task after retry failure.
Settings fail to automatically retry (to be verified) :
adds the following configuration to the tag of the XML file in the BPMN flowchart:

<serviceTask activiti:async="true" activiti:exclusive="false" activiti:expression="${demoService.getSentence(execution)}" id="demoServiceTask" name="demoServiceTask">
   	 <extensionElements>
		<activiti:failedJobRetryTimeCycle>R5/PT1M</activiti:failedJobRetryTimeCycle>
      </extensionElements>
</serviceTask>

(1) the configuration async is true, the default is false
(2) the R5/PT1M: said configuration retry count for each 1 minute try again once, retry a total of five reference:
https://my.oschina.net/go4it/blog/756149