[lsb-discuss] Printing session on next LSB meeting?

[Till Kamppeter]

On 12/19/2013 07:47 PM, Jeff Licquia wrote:
> We discussed this on the LSB call Wednesday.  To sum up for the sake of
> the archives and people on the CC list: we will likely have a LSB track
> as part of the Linux Foundation Collaboration Summit in 2014, to be held
> in Napa Valley, California.  More info on the Summit is here:
> 
> http://events.linuxfoundation.org/events/collaboration-summit
> 
> The details will likely be worked out sometime after the New Year.  We
> will make sure OpenPrinting is on the agenda for discussion.
> 

Important remarks in printing which could influence the LSB are:


1. Printing stack for mobile
----------------------------

The development of Linux operating systems is covering mobile more and
more, for example Ubuntu Touch. There are also TVs, cameras, ... with
similar requirements.

These systems have usually limited resources and so a more lightweight
printing stack is needed, especially no large collection of
printer-model-specific drivers can be held by these devices. As one
usually does not connect a printer directly to the device via USB but
rather prints via network and most network printers understand standard
languages (PDF, PostScript, PWG Raster, PCL 5c/e, PCL XL) one can do
well by supporting only these languages and discovering printers
automatically via Bonjour and setting them up automatically.

The future tends to driver-less/PPD-less printing.

In the near future there will be IPP Everywhere printers. These are
network printers advertizing themselves via Bonjour, using IPP 2.x as
data transfer/communication protocol, and at least PWG Raster
(optionally also PostScript, PDF, PCL, JPEG, ...) as Page Description
Language (PDL). These are ideal for driver-less printing from mobile
devices.


2. From CUPS 1.6.x on cups-filters is required
----------------------------------------------

>From CUPS 1.6.x on the CUPS package does not ship anymore the filters
which are not used in Mac OS X environments, therefore the cups-filters
package maintained by OpenPrinting (me) is required. cups-filters
handles the jobs in a PDF-based workflow which is different to the
original filter chain of CUPS 1.5.x and older.


3. foomatic-rip has moved into cups-filters
-------------------------------------------

In a Google Summer of Code project this year foomatic-rip was cleaned
from support for obsolete printing systems, leaving in only the support
for CUPS and for spooler-less direct call. CUPS is the only maintained
free software printing systems, all the others have (at least more or
less) died: LPD, GNUlpr, LPRng, PPR, PDQ, CPS. I have put this new
foomatic-rip into cups-filters to be maintained there and to eliminate
the need of the foomatic-filters package for the distributions. Probably
for LSB changes in the testing are needed.


4. Driver interfaces IJS and OPVP
---------------------------------

The LSB requires the driver interfaces CUPS Raster, IJS, and
OpenPrinting Vector (OPVP). At least in Europe and the US drivers are
only using the CUPS Raster interface, not the others. Especially HP with
their HPLIP drivers are CUPS-Raster-only now as they have given up the
IJS flavor. IJS is currently used only by a few drivers perhaps
supporting around 20 older printer models. I did not see any OPVP
drivers for Europe/US printers but it is possible that there are some
Japan-only printers using it, we need to ask the Japanese folks.

Perhaps IJS and perhaps also OPVP could be deprecated in the LSB.


5. Technologies: IPP, Bonjour/Avahi, D-Bus, UDEV
------------------------------------------------

The modern printing stack is a lot based on these technologies: IPP to
communicate with printers and remote (CUPS) servers, Bonjour/Avahi to
discover printing-related network resources (printers, servers), D-Bus
for the printing stack communicating with the user's desktop and
applications (esp. system components running as root interacting with
user software running as the user), and UDEV for discovering local printers.

We should look into getting these technologies into the LSB.


So there is a lot to discuss on a meeting, much more than new CUPS APIs.

   Till