[Printing-architecture] Some suggestions for the DNS-SD (Bonjour) printer support in the dialog

Michael Sweet msweet at apple.com
Thu Jun 13 14:05:49 UTC 2013


This would be a fine solution until cupsd (or some standard intermediary) does it.

The DBUS service would need to be a system-level service (root or a user account in one of the CUPS system groups) in order for it to auto-add/remove queues, but otherwise it would do the trick.

On 2013-06-12, at 6:52 PM, Till Kamppeter <till.kamppeter at gmail.com> wrote:

> On 05/19/2013 08:08 AM, Michael Sweet wrote:
>> The reason I mention DBUS is that it a simple way to implement a per-user spooler that provides "temporary" print queues.  This could also be part of cupsd (it used to be for CUPS browsing), but I want to be careful not to re-introduce the problems of CUPS browsing.
>> The key is that auto-adding every printer you see has a huge overhead and isn't particularly useful for the user when there are more than a few printers - how many printers does one user print to in the typical case?  Browsing and adding-on-first-use is a much better solution since then you just manage those printers you use on a particular system.
> What about cups-browsed offering a D-Bus service to create a temporary
> print queue, queue creation being triggered when a Bonjour-discovered
> network printer is selected in the print dialog and "Print" is selected.
> Queues are removed if they stay for a time X without job (preferred), on
> another D-Bus command, or on shutdown of cups-browsed. These queues get
> visible for other users, but this is no problem if they look the same in
> the other user's print dialog then. The job of the other user gets into
> the same temporary queue then and correctly waits until the first user's
> job finishes.
> This would make all print spooling be done by CUPS and not require any
> extra per-user or per-dialog spooler. Also if different users send jobs
> shortly one after the other, the jobs get correctly queued and cannot
> mix up.
>   Till

Michael Sweet, Senior Printing System Engineer, PWG Chair

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