Subject: Re: lpd and filter programs
To: None <tech-userlevel@NetBSD.ORG>
From: Greg A. Woods <>
List: tech-userlevel
Date: 07/30/1998 23:11:31
[ On , July 24, 1998 at 07:47:29 (GMT), Matthias Scheler wrote: ]
> Subject: Re: lpd and filter programs
> In article <>,
> > Really slick would be to integrate ghostscript into something like this.  Ie:
> > bob plugs in his printer, tells the magic configuration tool that he has "A
> > GoofyJet 500+" and things pretty much just work..
> That's exactly what the "magicfilter" package does. But to work properly
> with a network print server we need "lpd" to be modified.

Which is a perfect example of why the print spooling subsystems should
spool jobs to printers (and possibly configure printers to prepare them
for jobs), and other *optional* subsystems (possibly, though not
necessarily) layered on top of the spooling system should be responsible
for converting between output formats as necessary.

Yes, it's possible to configure BSD lpr in ways that emulate this model,
but it has a whole lot of goo that's unnecessary, and not enough support
for things that might be necessary for a true spooling system
(eg. notifying administrators when jobs requiring special forms or
"print wheels", etc. are ready to print, etc.).

As has been noted many times in the past there are many similarities
between a batch processing subsystem and a print spooling subsystem, and
often such systems have been used interchangeably with varying degrees
of success (with more success at making lp behave as a batch system than
lpr, so far as I know).  I think it should be possible to abstract the
particular requirements of each style of usage and design a system
suitable for both uses.

One other point I'd like to note:  WYSIWYG users don't really care how
the conversion between their document and the printer format happens,
but other users often care a whole lot more.  WYSIWYG systems are often
(always?) prepared to do the conversions themselves too.  So, with these
two facts combined I'd say there's little, or no, reason for the print
spooling system to ever manage document conversion duties.

							Greg A. Woods

+1 416 443-1734      VE3TCP      <>      <robohack!woods>
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