IPP> Re: MOD - RE: Base printer implementation requirements

IPP> Re: MOD - RE: Base printer implementation requirements

IPP> Re: MOD - RE: Base printer implementation requirements

Peter Zehler pzehler at ocp.mc.xerox.com
Wed May 7 11:15:42 EDT 1997


All,
____________
<snip>
JKM> As far as deriving base constraints goes, to me the real question =
is:
JKM>
JKM>    Must an "IPP Printer" must be able spool print jobs?
JKM> I would like to see an answer of "Yes", but clearly this is where =
desktop
JKM> printers (and many, if not most, network printers) fail to perform. =
 And I
JKM> believe this is usually the reasons behind most case of "we can't =
do that
JKM> due to printer limitations."


SAI>I fail to see why a "yes" answer matters?  If someone decides to =
implement
SAI>IPP in a printer that can not spool, what changes?  If it is too =
busy
SAI>processing one job and another comes in from another client, it =
returns a
SAI>"busy" or a "out of spool space"  just as in the case where a server
SAI>implementation supports 2000 spooled jobs and the 2001st job comes =
in. =20
<snip>
SAI>Will anybody implement IPP in a printer like this?  Probably not.  =
Does the
SAI>model preclude them from doing so?  No.   Will this type of printer =
ever be
SAI>used as as a shared network printer?  Probaly not, but if it is, and =
it does
SAI>not embed IPP then it can be front ended by a "server" that does.
__________
PJZ:
I have been listening.  I am prototyping IPP on a printer that can only =
accept and process a job at a time.  I chose this printer specifically =
to check the lower bounds of an IPP implementation.  I have to agree =
with Scott.   Spooling is not the printer feature that determines if a =
printer is capable of supporting IPP.  IPP will be sitting (somewhere) =
on top of TCP.  The flow control capabilities of this layer of the =
protocol should allow me to gate the inflow of PDL data while the =
printer "catches up" with the PDL stream.  I also have the job-k-octets =
to limit the job size for a low-end printer. =20
This class of printer will not be IPP feature rich.  The printer itself =
will not be feature rich.  It is true some clients will be denied =
service while the printer is busy. All services must handle the =
"capacity + 1" problem.  IPP seems to handle this problem.  There is =
still the issue for the application to determine when it should time =
out.  IPP level print job submission operations should help accomodate =
application level timeout detection.  We will have to see where the =
print operation semantics discussion ends up.
Will this type of printer be used as as a shared network printer?  Yes =
it can, if the workload is low enough.  If IPP service is not available =
often enough for the site's needs, an IPP spooler can be put between the =
client and the printer.  A bigger printer could also be used.
The factor that will determine if a printer can be IPP compliant will be =
the complexity of IPP, IPP conformance specification, and the available =
printer resources that are available for IPP.
_________________________________
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Pete                                                                     =
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