connectivity for BPM external custom UIs
I'd like to use the new PO feature of BPM tasks based on custom UIs deployed on external servers as documented on the help
Of course the application implementing the UI will be connecting to the BPM engine to fetch process data.
My question is related to connectivity the other way around:
does the BPM engine strictly need connectivity to the remote server where UIs are deployed?
In my understanding it should not be necessary since the url configured in http destination is only used by the user browser.
However I'm not sure whether it might be required for proper behavior or SSO.
Could anyone please assist?