[erlang-questions] how to check if an application has been upgraded

[Jay Nelson]

> I am for now polling from time to time the applications I have registered
> to watch if one have been upgraded and then optionally discover some
> resources from it.

Presuming you are using standard relup/reldown you should be able to
add a module to each application which will receive the upgrade / downgrade
notifications. Just make it an fsm that can transition on appropriate appup
instructions and then continue running in the upgraded state until you’ve
discovered the resources, after which it can transition back to the
‘WAITING_FOR_UPGRADE’ state.

jay