Printing and the XO

[david at lang.hm]

apologies for not maintaining threading, but I've just subscribed

on Wed Jan 2 16:43:39 EST 2008 Peter Krenesky said:

<nice overview of printing>
>==== Configuration - XO ====
>The number of printers, the models, and their locations will be
>unknown.  It may be 1 printer per school, or many depending on the
>country or region.
>
>Adding or selecting a printer needs to be simple.   Autoconfiguration is
>the best case scenario but some manual configuration is still needed.  A
>GUI is required for all of this.
>
>The presence service may be a way to discover printers and configuration
>information.  IE. the advertisement includes the configuration to be
>added to /etc/cups/printers.conf  A printer would really only be
>configured, once, at the server.
>
>Some unanswered questions are:
>    * What does this GUI look like.
>    * Where is it located within sugar.   Within the configure activity?

in the past when I have needed to support printing from many machines and 
have not wanted to have to change them all when swapping out a printer for 
a different model I have had very good success with the approach of just 
telling all the machines that they have a postscript printer and let the 
server do all the printer-specific conversions. if you really wanted to 
get fancy, let the server accept HTML as well as postscript to avoid the 
work on the laptop to convert things (although I suspect that the 
conversion of HTML to postscript is trivial enough to not be a big deal 
anyway)

this would be the first piece, because you really don't want to have to 
touch every laptop when you swap out one printer for another one.

at this point the remaining problem becomes picking which printer to use. 
For this you can get a _lot_ of mileage out of simply defining a default 
print queue (lp or printer, just pick something) and have the laptops use 
that queue on the school server they are registered to by default.

after that a simple dialog that lets you pick a different queue or a 
different server will cover almost everything else.

as for CUPS, I understand that it's the current fad for printing, but I 
question if it's the right thing to use for resource constrained machines 
like the XO. CUPS wants to have each machine load the printer driver and 
do the rendering for the printer before sending it to the server. the 
servers are almost certainly going to have more resources available then 
the laptops, and so there's a good argument to be made that the laptops 
should just send the unconverted print image to the server and let the 
server render it for whatever printer is attached.

the drawback to taking this approach is that it is harder to take 
advantage of all the features of the printer (paper sizes, trays, 
staplers, hole punches, etc), but while corporate users will miss these 
features, the vast majority of printers don't have such features and most 
people really don't care about them (they just want the image to show up 
on paper). the one feature that is worth going to some effort to produce 
is a way to print double-sided if the printer supports it, but it should 
be possible to do this in a way that won't interfere with normal printing.

David Lang