[cups.general] Passing extra information from environment to backend?

Kurt Pfeifle k1pfeifle at gmx.net
Tue Nov 6 15:30:17 PST 2007


Michael R Sweet wrote:
> Johannes Meixner wrote:
>> ...
>> As far as I understand the PassEnv documentation it means that
>> an environment variable which is known to the cupsd would be
>> passed to its childs but as far as I see, this doesn't mean
>> that a client program like "lp" passes the environment variable
>> to the cupsd.
> 
> Correct.  I think Kurt was leaning towards the "run a local cupsd
> as the logged-in user for that session" type of solution, such that
> the system-wide cupsd would not be involved.

That's right.

That's why I asked if Cendio are running a private cupsd per remote
session when printing is enabled, and on which side of the connection
(client or server) it runs.

That is the *only* sane, clean solution that I can think of given the
tools that are currently available if you want to have a strict sepa-
ration of session resources (i.e. each session does only "see" its own
printers; CUPS does not allow for that currently, so it is not good to,
say, dynamically create re-directing printers on session start-up and
delete them again upon session disconnection).

In any case, all this stuff of "remoting" the screen displays, virtua-
lization of (not only VM *machines*, but) desktops and individual app-
lications, "application streaming" is getting much attention in the
coming years. Server-based computing is on the rise (but it won't be as
simple as the traditional type with ThinClients/FatServers we know from
LTSP, Citrix or Windows TS).

Just google for "SVS", "VDI", "Net2Display", "SPICE", "SpeedScreen",
"NX", "NoMachine", "Teradici", "OpenQRM", "SoftGrid", "Virtuozzo",
"KVM", "OpenVZ", "klik", "Thinstall", "PC-over-IP", "Ericom", "HOBlink",
.... and you'll find several *dozen* of companies and projects that work
like crazy on this (and have products available), Free and Open Source
ones as well as proprietary.


All this will not abolish printing, but pose new challenges to be re-
solved in a satisfactory way for users.

-- 
Kurt Pfeifle
System & Network Printing Consultant ---- Linux/Unix/Windows/Samba/CUPS
Infotec Deutschland GmbH  .....................  Hedelfinger Strasse 58
A RICOH Company  ...........................  D-70327 Stuttgart/Germany




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