Handles failures for triggerable java service tasks

Flowable Engine
1

I’m not sure how to handle retries when it comes to handling failures for triggerable service tasks.

Let’s take a simple bpmn where it follows startEvent → serviceTask (async = true and triggerable = true) → endEvent

serviceTask (our custom JavaDelegate) makes rest calls to another service (let’s call serviceB) and goes to a wait state. Then serviceB will make callback to our flowable service with either SUCCESS/FAILURE callback. In case of SUCCESS callback, I can trigger and complete the task.

requirement: In case of failure callback, how do I ensure to retry the JavaDelegate.execute() method again? because the control of the flowable is in wait state of serviceTask now.

Our use case is to retry above requirement 3 times. After 3 retries move the execution to deadletter. When trying to bring back the execution from deadletter, again it should start from JavaDelegate.execute().

2

Hi, does anyone have some input to this issue. It would be very helpful.
Currently we are blocked due to this.

flowable version used: 6.4.1

3

What is a failure in this case? Is it a timeout → if so use a timer boundary event. Or is it a state being sent back? If so, why not model it with a loop back to the service task and store a process variable with a counter?

4

@joram, Yes it’s a state being sent from the external system.

We make http calls from our JavaDelegate and move to a wait state (as the serviceTask is marked triggerable = true). After this, we will receive a callback with status = SUCCESS/FAILED depending upon what happened with the processing of the http call we initially made.

In case of FAILURE state, we wanted to re-run the JavaDelegate again (and subsequently make another http call).