The official public repository for CUPS, an Apple open-source project widely used for printing on Linux, is all-but dormant since the lead developer left Apple at the end of 2019.
Apple adopted CUPS for Mac OS X in 2002, and hired its author Michael Sweet in 2007, with Cupertino also acquiring the CUPS source code. Sweet continued to work on printing technology at Apple, including CUPS, until December 2019 when he left to start a new company.
Asked at the time about the future of CUPS, he said: “CUPS is still owned and maintained by Apple. There are two other engineers still in the printing team that are responsible for CUPS development, and it will continue to have new bug fix releases (at least) for the foreseeable future.”
Despite this statement, Linux watcher Michael Larabel noted earlier this week that “the open-source CUPS code-base is now at a stand-still. There was just one commit to the CUPS Git repository for all of 2020.” This contrasts with 355 commits in 2019, when Sweet still worked at Apple, and 348 the previous year.
We asked Apple about its plans for CUPS and have yet to hear back. We also note Sweet is not counting on Apple's continued involvement. At the Linux Plumber’s conference in August, Sweet spoke on the future of printing in Linux, which you can also find on video here.
“How you print today is much different than 30 years ago,” Sweet said, explaining that development continues on IPP Everywhere, which is a protocol that can be used by clients to print to networked or USB-connected printers without any special software. The firmware in the printer should do all the heavy lifting in getting the print job done, once it receives the data via IPP, and this relies on the printer manufacturers implementing the protocol correctly. CUPS implements IPP Everywhere, so the hope is the printing system can benefit from improvements to the protocol.
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The documentation and code samples for IPP Everywhere can be found here in repositories belonging to the IEEE-ISTO Printer Working Group. Sweet said he “will be providing pull requests to Apple to incorporate these changes back into CUPS.”
Sweet is also working on LPrint, designed for the world of label and receipt printers, and PAPPL (Printer Application Framework), a C-based framework for creating printer applications that support IPP Everywhere, with a 1.0 release candidate planned soon. Note that these projects build on CUPS rather than replacing it.
If CUPS development, in effect, continues, where is Apple in all this? Till Kamppeter, leader of the Linux Foundation's OpenPrinting effort and organizer of the printing micro-conference at Linux Plumbers, commented on Larabel’s observations, pointing to this post where he says: “Due to dormant upstream development, we have discussed to creating a temporary fork on OpenPrinting [of CUPS] for bug fixes and distribution patches, and Michael Sweet has done it now."
The “dormant” bit refers to Apple's CUPS project; and OpenPrinting's CUPS fork is here. Kamppeter added that “in case that Apple does finally cease CUPS development, I will continue the project together with Michael Sweet on OpenPrinting. CUPS will still be needed in Linux.” In other words, it's forked, and it will stay forked unless Apple returns from whichever outer Earth orbit it is in.
CUPS, Kamppeter continued, “will drop PPD file support soon.” PPD is the old printer definition file used since way back when to describe printer capabilities for CUPS. At that point, “classic drivers consisting of PPDs and filters are not supported any more, and Printer Applications are the only form to supply printer drivers … the manufacturers are aware of the deprecation and soon removal of PPDs and the new standard way of Printer Applications,” he said.
Is Apple neglecting its open-source responsibilities, despite these big changes in the world of Linux printing? Since the key people working on these projects seem uncertain of Apple’s commitment, it does look that way, but who knows, it could change any time and the CUPS project could come back to life. ®