Hi, I attended PWG meetup this week - due COVID-19 the meetup was completely virtual.
The notes from the first day are attached, new PWG standards were discussed during next days - proposals can be found here https://ftp.pwg.org/pub/pwg/ipp/wd/?C=M;O=D . -- Zdenek Dohnal Software Engineer Red Hat Czech - Brno TPB-C
OpenPrinting plenary
---------------------
- cups-filters - moving to printer application - no remote PPDs, reliability
enhancements,
moves to stable API of poppler
- future - printing in SNAP/flatpack
- new PAPPL project - framework for printer apps
- ippusbxd vs ipp-go for ipp-over-usb printers
- avahi patch - for advertising local services on local machine only - finally
megred,
no longer blocks printer applications and ipp-over-usb
- GSoC prolonged by two weeks later due COVID-19
- OP will try to participate in Google Season of Docs 2020 - starts in
September to November,
can go to March for longer projects
GSoC 2019-2020
--------------
- GSoC 2020 selected projects:
- linux GUI app for IPP system service
- common print dialog backend with Qt
- IPP scan server
- General printapp SDK
- speed/scaling optimization of cups-browsed - needs specific HW, delayed due
COVID
- extract raster data from PDF to direct printing - needs specific HW,
delayed due COVID
- configurable printapps
- OP community bridge - funding openprinting projects
Printer Applications
--------------------
- two printapps - ippeveprinter (ippserver), LPrint
- framework PAPPL
- printapps = replacement for PPD, ppd options are now ipp attributes + driver
specific UI by printapp
- printapp is ipp everywhere printer - requires only PWG raster/PDF and JPEG
(for color printers)
- CUPS libs and ippsample are good means how to create printerapp
- compatible with old CUPS 1.4 and older
ippeveprinter
------------
- started as ippserver, has 3 modes - ppd-based postscript printer mode, basic
legacy postscript/pcl printer, attribute file mode
- good for testing, not for production
- enhancements - in ippsample and ippeveselfcert, Mike will provide pull
requests to Apple to incorporate the changes in Apple CUPS
- support resource files
- clone-printer script - collects attrs, icons and strings from a printer
LPrint
------
- in snap or github
- for common network or USB label printers
- based on ippeveprinter - multiple printer support via subset of IPP system
service, daemon is run on demand, it doesnt use CUPS backend
- is standalone spooling without CUPS and runs as ipp everywhere printer
- support raw, apple/pwg raster and PNG files
PAPPL
-----
- C framework for writing printer apps
- should support any kind of printer or driver in all environments
- base for gutenprint and LPrint
- supports JPEG, PNG, PWG, Apple Raster and "raw" printing to USB/network
printer
- license the same as CUPS
- framework supports adding others filters
- it generates specific printerapp and web pages based on your provided options
Openprinting projects
---------------------
- cups-filters
- now supports clustering
- no longer downloads remote PPD and creates PPD based on IPP request
- works with chunks of print queues
- filters supports zero-page input files -> zero-page output without error
- fallback during get_printer_attributes - for IPP-1.1 and then without
media-col-database
Future:
- change of license to the same as CUPS
- move more functions into libcupsfilters
- filters should be PPD-less, except for foomatic-rip
- take PPD functions from CUPS and create libppd library to allow converting
legacy drivers into printerapps
- cups-browsed as printerapp
- cups-browsed may be forked from cups-filters
- driverless scanning
- 3 standards - IPP scan(open PWG standard), eSCL(from HP, used by Apple
AirScan), WSD(from Windows and W3C)
- 2 projects - escl and airscan - will be merged into one, supporting all 3
standards and added into sane-backends
- sane-backends currently has escl backend, but since it will be merged into
airscan the escl backend was removed
in Fedora
- works via ipp-over-usb (ippusbxd, ipp-usb)
- goal is to rework scanning model due sandboxed packaging -> introducing IPP
Scan:
- scanning drivers will be scanning application, emulates IPP scanner
- IPP scan client is scanning app
- app uses IPP scan SANE backend, old SANE drivers in legacy Scanner
Application
- ipp-over-usb:
- ipp-usb
- written in Go, better http handling library, high memory footprint - main
disapproval from ChromeOS
- ippusbxd
- written in C, has several problems which are fixed in ipp-usb (due better
HTTP library in Go)
- ChromeOS person wanted to implement the features which works in ipp-usb,
but no activity since then
- CUPS Snap:
- has CUPS, cups-filters, cups-browsed, gs, qpdf, no classic drivers (cannot
get dropped into Snap
filesystem)
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