[cups.general] local filtering for remote unknown mime types

Michael Sweet mike at easysw.com
Thu Jul 15 08:27:47 PDT 2004

Hermann Lauer wrote:
> Dear list members,
> while trying to print from Mac OSX 10.3 to a CUPS 1.1.20 server
> (solaris machine) I stumbled over the following question:
> If the mime type application/pdf is disabled on the solaris server
> any pdf printed on the the MAC Client is rejected with a
> document-format-not-supported by the solaris machine. The cupsd
> on the mac received the available mime types of the solaris
> machine correct, so
> Why couldn't the local cupsd on the Mac filter the pdf to postcript
> locally ? (which sould produce superior quality compared to the
> xpdf conversion) 

That is questionable; I think Xpdf supports a superset of what the
cgpdftops filter does...

> I tried to search for such a solution, but up to now found no hint how
> to enable such a feature in the local cupsd.
> Please tell me if I overlooked something obvious.

We don't currently offer a generic solution for this; the PICT
format is a special-case, and quite frankly we've never had anyone
ask for this sort of functionality.

One issue with this is that the server may not support PostScript,
and in order to support remote raster printers you start getting
into a lot of rasterization and driver issues that are not easily
solved.  Many filters produce printer-specific PostScript as well,
so you'd be introducing potential problems there as well.

In addition, CUPS 1.2 passes ALL files in a job to the remote server
in one call (this particular code isn't commited yet, as we are
working out some kinks) so adding more logic would bloat the IPP
backend even further.

In short, we aren't keen to implementing more filtering into the IPP
backend since the potential gains are few and the potential for
harm is great (think network bandwidth usage, uncontrolled resource
usage on the local system, etc.)  PICT is and will always be a
special case, and its use will hopefully fade away now that Apple
has deprecated it.

Michael Sweet, Easy Software Products           mike at easysw dot com
Printing Software for UNIX                       http://www.easysw.com

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