[printing-discuss] RE: [printing-driver] proposal of what features the communication to aprinter driver should support

[Glen Petrie]

   I still think that defining a programmatic way to query the
   language level is feasible.  The driver developers could come up
   with a structure that describes how the language is formatted.  But
   you are right in that it would be difficult and perhaps error
   prone.

We need to define what a language is, first.  For PCL (at least the
LaserJet version) and PostScript, it's reasonably well defined, and
generally useful.  Probably even for ESCP, although there's the matter
of 9-pin and 24-pin printers.  I'm just not sure what good "ESCP/2
Raster" would do as a printer language; it's useless for actually
generating output unless the precise printer model is known.

[glen] Isn=92t the question of =93query the language=94 a question to the d=
river
about the input format the driver accepts?   So for PS, PCL, HG/GL this are
input languages that drivers accept; but, ESCP/2 is how the driver talks to
the printer not the =93language=94 if accepts (except in pass through mode).
In this context, wouldn=92t the possible range of =93languages=94 be someth=
ing
like;

Raw (I assume this means image data of some format)
PS
PCL
HG/GL
HTML
XHTML-Print
IPP
. . . . . .

------------------------------------------------------------------------

> It seems like a weird concept to me.  With on-the-fly output
> generation, this can be done with most inkjets, but it still feels
> very strange to me.  With laser printers, this doesn't make a whole lot
> of sense at all, and even I have difficulty envisioning a situation
> where this would be useful.  In any event, aborting a page is
> something I think we should defer.

Yes.  I agree.  It was a weird concept for me as well.  Which is why
I chose to go with the abort job path.


[glen] I hope you reconsider the abort-page.   Example; some print manager
process has defined a 200 page job and began a session with the driver.  The
driver has accepted the job, printed 199 pages and start page 200.   The
toner (ink, whatever) is reported out (or the paper is out) via the
status/monitoring I/O channel from the driver to the print manager process.
Does the print manager process abort the entire job and restart or does it
abort the current page; wait for the problem to be resolved; then resend
page 200 to complete the job.

[glen] If the driver is managing the entire job =96 it received (or at least
has means to access) all pages, then an API call for abort-page is not
necessary since processing is done internally.

------------------------------------------------------------------------

But even if we're not talking about a raw file (and I seriously hope
we're not; those things are just too big!), I think we should take a
higher level look at what constitutes a "similar print queue" from the
user's perspective.  Suppose I have three printers:

  Epson Stylus Photo 780
  Canon S800
  Epson Stylus C80

Suppose the 780 is down, but there are some (non-raw) files queued for
it.  Which printer should they be diverted to?  It isn't clear.  Most
likely I would want to divert it to the S800 (which is a very high
quality, 6-color photo printer), not to the C80.  The reasoning -- and
this cannot be captured by knowing anything about the familial
resemblance -- is that the C80 is a fast 4-color printer, so if I'm
printing to the 780 I'm probably printing a smaller graphic with more
demanding quality requirements.

[glen]  I am not sure I understand the group=92s definition of a =93print q=
ueue=94
.    I think of a =93print queue=94 as process that manages a set of similar
=93printer queues=94.   In other words, there can be any number of devices
associated with a =93print queue=94.   All of those devices have common
capabilities.  In this example, the Epson Stylus Photo 780 and Canon S800
belong to the same =93print queue=94 (each printer has their own =93printer
 queue=94) while the Epson Stylus C80 would belong to a =93print queue=94
consisting of 4-color inkjet printers.    The challenge is to define the
classes of =93print queues=94 =96 this may be doable by using the informati=
on from
[printing-cap] sub-team effort.


Rgds,
Glen W. Petrie
Manager, Software Printing Solutions
Epson Imaging Technology Center
150 River Oaks Parkway, Suite 200
San Jose, CA, 95134
Voice: 408.576.4131  Fax: 408.474.0511

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