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Re: Apple raster, PWG raster and non-free filters/drivers

On Mon 16 Jan 2017 at 15:51:15 -0200, Till Kamppeter wrote:

> On 01/16/2017 03:32 PM, Brian Potkin wrote:
> [...]
> >The word "if" supports your idea of a GCP printer having only to process
> >one of PDF or PWG raster. The page
> >
> > https://developers.google.com/cloud-print/docs/proxyinterfaces
> >
> >does talk about PWG raster as a fallback to PDF but does not mandate it,
> >although I suppose a printer manufacturer could choose to provide it in
> > addition to PDF for that purpose.
> >
> >I'm abandoning my contention and moving on to more fruitful things.
> >
> My question is here whether the Google Cloud Print server polls printer
> capability info from the printer or whether it has a database with info
> about thousands of printer models? In the latter case we do not have
> driverless printing here and a GCP printer has its model capabilities in
> Googles database, in addition to understanding one of PWG Raster and PDF.

I do not know whether any sort of a database is used, but suspect not.


During the registration phase the capabilities are obtained. I can only
connect a classic printer and have seen the PPDs of the queues being
uploaded (over an XMPP/https connection, I suppose). The downloaded file
for a job is a PDF.

I do not have a Cloud Ready printer so assume the printer's firmware is
queried in the same way.

> So the fact that a printer is a GCP printer only helpos for driverless
> printing if Google can actually poll the printer's capabilities from the
> printer and if Google publishes the protocol for this kind of poll.

The Chromium browser (and Chromebooks, I believe) can do driverless
printing through GCP from the point of view of the user. The technique
does not involves CUPS. I understand the significance of the term
"driverless printing" when applied to CUPS+cups-filters+cups-browsed
but, at the same time, it is quite a well-used and general term whose
implementation depends on the service being used.


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