Re: Does anyone know how to configure a Brother MFC-J5720DW with cups?
On Sun 13 Mar 2016 at 22:48:07 -0500, David Wright wrote:
> On Sun 13 Mar 2016 at 19:32:04 (+0000), Brian wrote:
> >
> > I've said specifically it has a PDF converter. It must have; the printer
> > does not understand PDF.
>
> Once again, I don't understand this statement because I don't
> understand your terminology...
"PDF filter" would be a suitable substitute for "PDF converter". But not
"PDF interpreter".
> My question with pronouns removed: "So if a PDF arrives by AirPrint,
> how does the MFC-J5720DW printer interpret the PDF if the MFC-J5720DW
> printer doesn't have a PDF converter?"
>
> Your response AIUI with pronouns removed: "I've said specifically the
> MFC-J5720DW printer has a PDF converter. The MFC-J5720DW printer must
> have; the MFC-J5720DW printer does not understand PDF."
>
> Is that what you mean to say? If not, couuld you replace the
> appropriate nouns by different nouns.
Yes. But maybe my understanding of what an onboard PS/PCL/PDF interpreter
does (stated in an earlier mail) is different from yours.
> None of your examples (the bits -> like -> this) have "AirPrint"
> mentioned in them. I'm trying to learn from you what AirPrint is and
> what it does. And yet your statements about it say things like
> "The AirPrint facility handles a PDF (it has to)." and "Substitute PS,
> PCL, QPDL etc for BUL to see how other manufacturers might deal with
> AirPrint." which tell me nothing specifically about AirPrint.
We seem to be both agreed that a PDF arriving at an AirPrint-compatible
printer has to be dealt with in some way to ready it for printing. Let's
leave it there. It is interesting to speculate how a printer processes a
PDF sent from a driverless device but ultimately it is of no great
consequence because it is not under our control.
> > The part played by what is in the Bonjour broadcasts is crucial to the
> > whole thing working. Apart from the questionable use of cp, IPP is used
> > for printing and is what is advertised in the broadcasts.
>
> OK. I can see that CUPS has some work to do to find the printer with
> whatever it uses (dnssd/avahi/bonjour/...). That part doesn't really
> interest me in this discussion.
It really should. Without Bonjour broadcasting by the printer AirPrint
would not exist.
> > The CUPS backend converts PDF to BUL.
>
> Why bother? The AirPrint technology built into the MFC-J5720DW printer
> can do that. Why can't CUPS send PDF down the wire to the printer,
> thereby avoiding all the driver-crap? You've just said "The AirPrint
> facility handles a PDF" (requoted above). Why not let it do so?
Why not, indeed? The Bonjour broadcasts of the printer should be picked
up by avahi-daemon and the printer listed in the print dialogues of some
applications (e.g Iceweasel/Firefox). These applications produce PDFs as
a matter of course. They are sent directly to the printer and the
printer sorts them in some way. No filtering on the machine is
necessary so cupsd is not involved, whether or not it is on the system.
This implementation of this idea was the objective being worked towards
in
https://lists.debian.org/debian-user/2016/03/msg00401.html
as a solution to Jarle Aase's issue. All we need is someone with an
AirPrint printer to test it. :).
But if the printer is not AirPrint-compatible we will need cupsd and the
backend filter. (That lead to the discussion of what happens on the
printer).
> > But, as it happens, you do not
> > need cupsd to print to an AirPrint printer.
>
> OK. What's the minimum that you _do_ need? By minimum, I'm meaning
> things like drivers; the things that linux users get tripped up by;
> the things that make "perfectly functional" printers into doorstops.
When cupsd isn't running no drivers are needed because the print job is
sent directly to the AirPrint-compatible printer. avahi-daemon is
required, of course.
When sent to a non-compatible printer the minimum number of drivers
needed is determined by the printer make and model when it is set up as
a local or remote shared printer with CUPS.
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