[Printing-architecture] Request for comment to PCM draft

McDonald, Ira imcdonald at sharplabs.com
Sat Feb 11 11:21:13 PST 2006


Per current work (and minutes) of the FSG/OP Architecture WG,
both Status Monitoring and Device Discovery are first-class
_independent_ modules of the FSG "Open Printing System".

PCM should be _strictly_ concerned with establishing connections 
and/or paths to already _known_ services and devices and passing 

Neither PCM nor Status Monitoring should ever attempt to do 
their own device discovery.

The purpose of the FSG "Open Printing System" architecture is NOT
simply to serve the convenience (and current implementation design) 
of CUPS (or any other printing software).

Neither is the purpose simply to serve desktop printing needs.

The purpose is to define a single common printing architecture 
that spans from very low-bandwidth devices (e.g., PDAs and 
cellphones) to professional production printing devices and
can be implemented on any Linux, UNIX, or other operating

- Ira

Ira McDonald (Musician / Software Architect)
Blue Roof Music / High North Inc
PO Box 221  Grand Marais, MI  49839
phone: +1-906-494-2434
email: imcdonald at sharplabs.com

> -----Original Message-----
> From: printing-architecture-bounces at lists.freestandards.org
> [mailto:printing-architecture-bounces at lists.freestandards.org]
> On Behalf
> Of Michael Sweet
> Sent: Friday, February 10, 2006 4:50 PM
> To: Ide Kentaro
> Cc: printing-architecture at freestandards.org
> Subject: Re: [Printing-architecture] Request for comment to PCM draft
> Ide Kentaro wrote:
> > Hi, folks,
> > 
> > I posted link of PCM draft document to OpenPrinting web site.
> > 
> <http://www.openprinting.org/moin.cgi/OpenPrinting/PrintChanne
> lManager>
> > 
> > I would like you to comment these documents with two viewpoints.
> > 
> > 	1. Architecture
> > 		If you predict that a problem occurs to your 
> system with this architecture,
> > 		point out the problem, please.
> 1. Architecture Diagram
>     It isn't clear how this will work with CUPS; the architecture
>     diagram references an "Open Printing System", but the diagram
>     does *not* match up with how CUPS interfaces with and discovers
>     devices.
>     Basically, I'd focus on the PCM design/architecture itself, and
>     then show possible interfaces with other apps like CUPS, SANE,
>     and so forth.  All of the PCM stuff should be in the middle,
>     possible apps/users at the top, and devices at the bottom.
> 2. Device Discovery
>     The spec and API only focus on accessing a particular device.
>     There is no way to discover or enumerate devices, which is
>     most definitely going to be needed.
> 3. Asynchronous I/O, Non-Blocking IO, and/or Timeouts
>     The read and write APIs need to support non-blocking I/O or at
>     least basic timeouts so that an application can communicate
>     without getting hung/deadlocked.
>     It would also be useful to get a file descriptor or some
>     other mechanism so that you can poll() or select() for
>     ok-to-read/write conditions.
>     Without this, you are forced to use threading which is
>     problematic.
> > 	2. License
> > 		My questions are "Which license is better for us?" and
> > 		"As for we should we select the license that was unified
> > 		with all the Open Printing documents? ".
> > 
> > 		We chose BSD like license to PCM specification, today.
> > 		But some other documents chose another license as FDL.
> > 		One of the license of a BSD derivation may be 
> easy to accept,
> > 		in the case that the application in business with one,
> > 		although it is natural to use FDL and the licenses of
> > 		other GNU derivations, if I think with the position
> > 		that says FSG.
> > 		So, comment your idea about license of these 
> documents, please.
> As far as licensing goes, BSD or LGPL is suitable for the code, but
> simple copyright (with FSG as the copyright holder) should be used
> for the spec since you don't want to have others modify the spec
> once it has been accepted.
> That is, specifications/standards documents are normally controlled
> by the organization that produced them...
> -- 
> ______________________________________________________________________
> Michael Sweet, Easy Software Products           mike at easysw dot com
> Internet Printing and Document Software          http://www.easysw.com
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> ng-architecture

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