[Printing-architecture] On the Continued Need for PostScript Workflows

Michael Sweet msweet at apple.com
Tue Jun 18 12:13:44 UTC 2013


On 2013-06-17, at 8:45 PM, Ira McDonald <blueroofmusic at gmail.com> wrote:
> Hi James,
> I sympathize with your concerns, but...
> (1) PostScript filters aren't going to be maintained in CUPS in the future
> (as far as I know)

This isn't exactly correct.

The CUPS PPD APIs were deprecated in CUPS 1.6 in favor of new APIs based on IPP Everywhere that better abstract the implementation details of printers and drivers in the system.  In fact, the current implementation is (internally) based on PPDs, as that is how CUPS does printer drivers.

The goal is to eliminate dependence on PPD files, not to eliminate PostScript printing specifically, because PPDs are (and always were) a limiting factor in supporting printer features in CUPS.  The last update to the PPD spec was in 1996 - printers (and how they are used) have changed a LOT since then...

Once applications and drivers no longer depend on the CUPS PPD API, we can work to separate the PPD API and PostScript printer support so that it can be maintained in parallel to any non-PS support.

> (2) PWG IPP Everywhere (the only open standard mobile printing protocol)
> abandons PostScript entirely and requires PDF

Just to be clear: IPP Everywhere does not forbid PostScript, and in fact is completely silent on support for it.  I suspect that future IPP Everywhere printers may offer PostScript support as part of the "legacy" language support for older OS's.

> (3) Of the recent printers that I'm aware of, more are supporting native PDF
> than native PostScript

My view of the products coming out does show some new products that are PDF-only vs. PDF + PostScript.  The combo products typically use a RIP (internal or external) that supports both with a common rendering backend, usually with an intermediate display list representation (for banding).

Most printers are still raster-only, but there are some new printers in the sub-$250 price point that are offering PDF support now...

> (4) PostScript is deservedly disliked by government standards agencies 
> around the world because of how easily it can be exploited for security
> attacks

In the realm of security, PDF has its share of issues as well.  I avoid slinging the security arrow because of that...

Michael Sweet, Senior Printing System Engineer, PWG Chair

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