AW: [Desktop_printing] Role of CUPS and error handling

Michael Sweet mike at easysw.com
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        http://www.easysw.com



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