AW: [Desktop_printing] Role of CUPS and error handling

Michael Sweet mike at
Fri Mar 31 17:59:42 PST 2006

Robert L Krawitz wrote:
> ...
>    (Note that I'm deliberately not addressing the issue of
>    proprietary, binary-only drivers.  I don't think that as an "Open
>    Source Development Lab" forum we should be particularly encouraging
>    binary-only drivers.  Aside from philosophical issues that people
 > ...

I'm sure this is going to be a sticking point for many at the summit,
I'm of the opinion that OSDL can *encourage* open source drivers but
definitely should not discourage or "punish" vendors that, for whatever
reason, choose to only ship binaries.  IOW, use a carrot, not a stick.

Aside from philosophical issues, there is also the pragmatic issue that
most users are not comfortable compiling software and will not have
compilers installed.  Assuming that a vendor wants to provide pre-
compiled binaries, they will want to be able to provide a common,
presumably LSB-compliant package rather than a different package for
each distribution.

Yes, Linux distributors can provide binaries, but in my experience it
is better for the developer to do the packaging rather than a bunch
of distro packagers that will do things differently - in almost all
cases, that leads to a better user experience.

 > ...
> 3) Finding the printer.  This gets harder.
>    Different distributions/operating systems use different naming
>    conventions and different ownerships for printer devices.  There's
>    still the problem that if the printer's not turned on when CUPS is
>    started it isn't visible to CUPS.

That's so CUPS 1.1.x... :)

CUPS 1.2 does a device scan every time you ask for the list of
available devices, so it will find newly connected printers right
away, no restarts, reboots, etc.

> 4) Bouncing CUPS to get it to recognize the new PPD file.  This is
>    somewhat vendor-specific; for starters, BSD-init systems do it very
>    differently from sysvinit-based systems.  Service management seems
>    to be an area for vendor creativity, also.

Again, this issue is gone in CUPS 1.2.

> ...
> It's a bit harder than that if you want to do bidirectional
> communication with the printer.  A lot of Windows users are used to

Again, CUPS 1.2 supports back-channel data, so a single driver/filter
can communicate with the printer.

> ...
> I won't get too far into my generic beef with PPD files here.  Read my
> slides for more on that.
 > ...

... and be sure to read mine.  For all but your lookup table option
type, CUPS 1.2 has this covered.

Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Publishing Software

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