IPP> MOD - part of Issue 17 - don't need negative "time-at-xxx" Job Attributes

IPP> MOD - part of Issue 17 - don't need negative "time-at-xxx" Job Attributes

IPP> MOD - part of Issue 17 - don't need negative "time-at-xxx" Job Attributes

Anthony Porter anthony.porter at computer.org
Mon May 3 04:36:28 EDT 1999


It is just that the printer clock may be wrong. If the user sees server
times it is possible to get a picture of the job.  For example, if server
time is 20:34 and the job started printed at 20:29 server time, the user can
imagine that this particular job is nearly done, even if local client time
is 13:15.

On the other hand if the time is 13:15, and the user sees that the job
started printing at 13:29, the user hasn't a clue what is going on.

The problem with summertime is that there are so many different ways to
adjust for it.  Some people adjust the time zone, some leave the time zone
and change the clock, some click on a check box somewhere.  The printers on
our local network here all display a time one hour in the future.  That is
an operator error of course, but nevertheless, come summer, half of the
printers are likely to return the wrong time.

That is why I still think that it is better for the server to return the
elapsed time since the event occured for the job events.  The client can
convert that into local times, the server doesn't need a clock and the only
error is network latency.
Anthony Porter

-----Original Message-----
From: owner-ipp at pwg.org [mailto:owner-ipp at pwg.org]On Behalf Of Hastings,
Tom N
Sent: Friday, 30 April, 1999 8:18 PM
To: anthony.porter at computer.org
Cc: 'ipp'
Subject: RE: IPP> MOD - part of Issue 17 - don't need negative
"time-at-xxx" Job Attributes


Anthony,

It is ok to say that a client SHOULD display times to users using the client
local time?

So when displaying a queue of jobs, I'd like to see the client convert the
time returned by the server from whatever times the server returns to my
local time zone.

I didn't understand the comment about summer time, since my understanding is
that the so-called "time zone" field in the dateTime data type is NOT really
time zone, but rather is the offset in minutes from UTC time (which doesn't
change in summer).  So a Printer could have a different offset from UTC time
during summer time than winter time.  Or a Printer could always use UTC (or
Zulu) and have the offset be 0 all year long.

Tom

-----Original Message-----
From: Anthony Porter [mailto:anthony.porter at computer.org]
Sent: Wednesday, April 28, 1999 02:12
To: 'Hastings, Tom N'
Cc: 'ipp'
Subject: RE: IPP> MOD - part of Issue 17 - don't need negative
"time-at-xxx" Job Attributes


Tom,
Yes, the time zone should be the local time of the printer.  I think that if
the printer supports time, then it must support time zones, and allow the
operator to change it.  The operator may have a good reason to set the time
zone to UTC on a particular printer, but it is a problem if the operator
cannot set the local time zone at all.

I am not sure that the specification should say how the client displays
times.  I think that it is more useful if the client displays server times,
together with the current server time.  If the client converts times to
local, it is relying on the client and server clocks being synchronized,
with the correct time zones and the proper allowance for summer time.

Anthony Porter

-----Original Message-----
From: Hastings, Tom N [mailto:hastings at cp10.es.xerox.com]
Sent: Tuesday, 27 April, 1999 8:30 PM
To: anthony.porter at computer.org
Cc: 'ipp'
Subject: RE: IPP> MOD - part of Issue 17 - don't need negative
"time-at-xxx" Job Attributes


You said:

>The job-hold-until attribute depends on the time-zone, so a printer that
>supports the "printer-current-time" attribute should support its local
>time zone.

Good point.

In other words, the time zone offset that comes back when a client queries
the "printer-current-time" SHOULD/MUST be the local time of the printer.

If we clarify the "printer-current-time" this way, then a client could also
use the "printer-current-time" to determine the time zone of the Printer,
whether the "job-hold-until" attribute is supported or not.  Something that
might be useful for the user submitting a job.

So we should change the clarifying sentence that I added to
"printer-current-time" from:

The time zone in this value NEED NOT be the time zone of the Printer object
or device.  Therefore, the vendor MAY ship the implementation using GMT, for
example, with no way to change the time zone.  The client SHOULD display any
dateTime attributes using the time zone of the client.

to:

The time zone in this value SHOULD be the time zone of the Printer object
or device.  Then the client can use this attribute to determine the time
zone of the printer, even though clients SHOULD display any dateTime
attributes to users using the time zone of the client.




Ok to make this a SHOULD, instead of a MUST?

Other comments?

Tom




More information about the Ipp mailing list