IPP Mail Archive: RE: IPP> MOD - Use of time [and Bake Off 2 Issue 17]

IPP Mail Archive: RE: IPP> MOD - Use of time [and Bake Off 2 Issue 17]

RE: IPP> MOD - Use of time [and Bake Off 2 Issue 17]

Stefan Andersson (stefan.andersson@axis.com)
Wed, 24 Mar 1999 15:46:02 +0100 (MET)

On Wed, 24 Mar 1999, Zehler, Peter wrote:
> The HTTP layer requires a time stamp. Simple time protocols exist that
> are very light weight. A page can be made available in the embedded we=
b
> server to set the current date and time. If all else fails the time ca=
n be
> grabbed from incoming HTTP packets.
>=20

It is true that the HTTP layer requires a time stamp, but there is an
exception to this rule. From draft-ietf-http-v11-spec-rev-06.txt=20
14.18 Date:
3. If the server does not have a clock that can provide a
reasonable approximation of the current time, its responses MUST =20
NOT include a Date header field. In this case, the rules in
section 14.18.1 MUST be followed.

To add a page for setting the current date and time is not a good idea. I=
f
a date is to be useful the client must be sure that the clock isn't
reseted between requests. The same argument can be used against grabbing
it from incoming HTTP packets, the server will have no way to control tha=
t
the incoming date/time is correct. The only way to get a date that would
work is to use for example NTP.

Since the Date field probably is most useful for clients when the server
is spooling. I would recomend one of this alternatives:
1) Add optional attribute that gives the time in an absolute form.
2) If the server can answer in an absolute form it should do that
otherwise it will answer in an relative form as the protocol states
today. =20

/Stefan

--
Stefan Andersson                         Software Engineer
Print Server Business Unit               Stefan.Andersson@axis.com
AXIS Communications AB                   Phone: +46 46 270 19 85
Scheelev=E4gen 16                          Fax: +46 46 13 61 30
S-223 70  LUND, SWEDEN                   http://www.axis.com