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. See https://developers.google.com/cloud-print/docs/devguide 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. -- Brian.
