ConfD warning capability towards clients

In manual for ConfD there is the following paragraphs:

“We also have yet another special return value which can be used (only) from the validate() callback which is CONFD_VALIDATION_WARN. Prior to return of this value we must call confd_trans_seterr() which provides a string describing the warning. The warnings will get propagated to the transaction engine, and depending on where the transaction originates, ConfD may or may not act on the warnings. If the transaction originates from the CLI or the Web UI, ConfD will interactively present the user with a choice - whereby the transaction can be aborted.
If the transaction originates from NETCONF - which does not have any interactive capabilities - the warnings are ignored. The warnings are primarily intended to alert inexperienced users that attempt to make - dangerous - configuration changes. There can be multiple warnings from multiple validation points in the same transaction.”

My questions are:
a) The mentioned Web UI and CLI are integrated to ConfD?
Can you share a more detailed description on how a warning case scenario works?
Which interface is used?

The premium version of ConfD provides support of various northbound interfaces including CLI, and JSON-RPC API which can be used to build a WebUI.

In addition to the user documentation, the best way to understand this is to go through the examples that come with ConfD Basic. The two examples under examples.confd/valildate called c and c_dependency shows how warnings are being used.