In october of last year we share the news here on the blog about the OpenPrinting project (supported by Linux Foundation) which created a branch of the CUPS printing system, where the most active part in development is by Michael R Sweet, the original author of CUPS.
And it is that after more than six months from that time, till kamppeter, leader of the OpenPrinting project, announced that due to lack of interest from Apple in maintaining the CUPS printing system, the CUPS fork, founded last year, can be seen as a start-up project of patches and distributions. The development of the fork is involved with Michael R Sweet, the original author of CUPS, who left Apple a year and a half ago.
Since early 2020, no changes have been made to the CUPS repository maintained by Apple and the project is in deep stagnation. Given the importance of CUPS to the Linux ecosystem, the OpenPrinting team decided to take CUPS code maintenance into their own hands and released a fork last fall. Six months have passed since the fork was created and Apple has not resumed work on CUPS.
In response to a request from Michael Sweet, Apple confirmed its lack of interest in further developing the CUPS functionality and intends to limit itself to maintaining the code base for macOS, including migration of fixes from the OpenPrinting fork. The OpenPrinting developers have announced that development will continue independently of Apple and have recommended that their branch be considered a major project. Future versions of the CUPS fork will ship with the project name retained and without the previously used "opX" suffix.
Among the changes already added, the integration of accumulated patches stands out in the package for Ubuntu, as well as the addition of the necessary capabilities to distribute the CUPS-based printing stack, Ghostscript, and Poppler in a Snap-format package (Ubuntu plans to switch to this plug-in instead of the usual packages). Another aspect of the job is to fix bugs that have been reported to the Apple repository in the last 15 months.
It is planned to include the changes in version CUPS 2.4, It is also expected to include compatibility with AirPrint / Mopria, as well as to add support for OAuth 2.0 / OpenID authentication, pkg-config support, improve TLS and X.509 support, among other changes.
Later, at the CUPS 3.0 release, it was decided to stop supporting the PPD printer description format and switch to a modular printing system architecture, completely free of PPD and based on the use of the PAPPL framework to develop printing applications based on the IPP Everywhere protocol.
The separate modules will include components such as commands (lp, lpr, lpstat, cancel), libraries (libcups), a local print server (responsible for processing local print output requests) and a shared print server (responsible for the network printing).
Let us remember that the organization OpenPrinting was created in 2006 as a result of the merger of the Linuxprinting.org project and the OpenPrinting working group of the Free Software Group, which was developing the architecture of the printing system for Linux (Michael Sweet, author of CUPS, was one of the leaders of this group). A year later, the project came under the wing of the Linux Foundation.
In 2012, the OpenPrinting project, according to Apple, took over the maintenance of the cups-filters package with the necessary components for CUPS to work on systems other than macOS, since since the release of CUPS 1.6 Apple has discontinued support for some print filters and backends used in Linux, but not of interest to macOS, and also deprecated the PPD drivers.
During his time at Apple, the vast majority of changes to the CUPS code base were made personally by Michael Sweet.
Finally if you are interested in knowing more about it, you can check the details In the following link.