Re: Recommended way to manually add an undiscovered IPP printer in CUPS 3.x

Thank you for the explanations. I think I now understand the
separation between printer profiles, the local server, and the sharing
server.

My current understanding is the following:

1. cupsEnumDests() should be the source of truth for the destinations
displayed on the main Printers page.
It can return automatically discovered IPP destinations, remote CUPS
queues, Printer Application destinations, and eventually destinations
supplied through profiles.
Therefore, a destination must still be displayed even when I cannot
find a corresponding local DNS-SD advertisement.

2. DNS-SD should be an enrichment and grouping source, rather than the
authoritative destination list.
I currently use Avahi to obtain information such as the service
instance, hostname, port, resource path, TXT UUID, and the
relationship between _ipp._tcp and _ipps._tcp advertisements.
I will correlate this information with the destinations returned by
cupsEnumDests() and use it for physical-device grouping. Where
possible.

3,. COSMIC Printers should not create or edit printer profile files.

4. Profiles belong to the local-server/libcups discovery mechanism.
When libcups supports them, profile-defined destinations should appear
naturally through cupsEnumDests().
Queues owned by the sharing server are a separate concept.
I should query the sharing server using its IPP System Service
operations, such as Get-Printers, when I specifically need to list or
administer the queues owned by that server. I should not infer that
every destination returned by cupsEnumDests() is a configured
sharing-server queue.

5. A normal driverless destination returned by cupsEnumDests() is
already usable and does not require an Add operation. A queue on the
sharing server should only be created if the user explicitly requests
server-side sharing, relaying, accounting, access control, or similar
policies, for example, when the user opens the Add Printer dialog and
selects that printer.

6. For an undiscovered driverless printer entered manually via IP
address or hostname, printer setup tool should probe it using
Get-Printer-Attributes and then create a queue for it on the sharing
server.

Thanks,
Abdelrahman