Re: [Gnome-print] Re: [Gimp-print-devel] An introduction to gnome-print (fwd)

[Michael Sweet <mike easysw com>]

Ben Woodard wrote:
> ...
> hands you a BLOB (big lump of binary data). You initiate a
> connection to the printer, read the page count, send the BLOB, then
> read the page count again. Virtually any printer which would be used

Not all printers (or connection types) support a status channel with
page information.

> in a setting in which accounting must be done has some sort of
> pagecount either through PS or SNMP. In the worst case almost all

Inkjet printers are very popular in corporate environments - cheap
initial cost and reasonable quality - and few inkjets (basically
the PS capable ones) provide page status/count info.

> printers have some sort of JCL in addition to the PDL. You cand
> divide a job up into three pieces, the first and last detect count
> the pages.

Again, this isn't usually available with inkjet printers.

> Plus, you cannot depend on DSC to give you any semblence of an
> accurate accounting of page utilization. People have been hacking
> PS/DCS to give false readings ever since I was in in college (circa
> 1989 -- I know, I did it).

True, but you can hack the page counter on some printers, too.

However, we're missing the mark here - for non-PS printers (most
of which do not support hardware page counters) we use a RIP,
for which the drivers can provide an accurate page count as they
send the job.

(before someone says, "then we can provide accounting info from
 GNOME-print to the printing system", remember that a malicious
 user can just as easily send false information; better to put the
 accounting in the print server which is "controlled", as well as
 providing accounting for non-GNOME printing)

> Why don't we simply specify the "submit_job" spooler interface call
> must have a pagecount parameter if accounting is turned on.

Because that isn't any more reliable than using DSC comments, and
doesn't address accounting for other apps.

> ...
> Quite a few universities are using my program npadmin,
> http://npadmin.sourceforge.net, to track actual page utilisation. As
> long as the printer is either an HP or supports RFC 1759 then it
> should work.

That works for most network printers, but what about inkjet or
specialty printers, which are far more costly to operate?

And how do you track usage by user/group then?

> ...
> This number went down the bigger the printer you bought. I would
> bet that the total operating cost of the new high quality ink jet
> printers is remarkably high.

Especially if you use anything other than plain paper...

Quick comparison for the typical lifetime of a HP laser printer toner
cartridge vs. an equivalent number of EPSON ink cartridges and paper:

                                B&W Laser  Color Laser  Inkjet
    5000 sheets of paper        $60        $60          $600
    Toner/ink for 5000 pages    $100       $520         $1040
    Total cost for 5000 pages   $160       $580         $1640

Laser pricing based upon HP LaserJet 4000 and Color LaserJet 4500
and Hammermill 24lb LaserPRINT paper.

Inkjet pricing based upon EPSON 720dpi inkjet paper, 25 black,
and 20 color cartridges.

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products                  mike@easysw.com
Printing Software for UNIX                       http://www.easysw.com