Hugo,
In your proposal for the "IPP Notification Delivery Protocol over HTTP", we
need to do whatever we can to make it most likely that fire wall
administrators will allow the notifications to flow out across the firewall
that contains the IPP Printer AND flow across the firewall that contains the
Notification Recipient.
In addition to using a new scheme (ipp-ntfy) and a new default port (???),
how about also using a new HTTP method for the "IPP Notification Delivery
Protocol over HTTP"? Perhaps we could call the new method "notify" or
"send-notifications".
Tom