Thanks for the clarification @selkhlifi. You basically covered all the areas.
Since this is still not released and under development you can have a look at:
There is also a dedicated REST api under external-job-api in the flowable-external-job-rest module. There will be a dedicated Swagger documentation for it as well.
Please have a look at it, try it out and any feedback is very appreciated so we can improve on this before the final release.
Cheers,
Filip