W3C home > Mailing lists > Public > ietf-http-wg-old@w3.org > September to December 1994

Re: More followups

From: Keith Ball <kball@kballuw.sjf.novell.com>
Date: Mon, 5 Dec 1994 16:06:33 pst
Message-Id: <9412060007.AA20494@ka.SJF.Novell.COM>
To: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
> From "Roy T. Fielding" <fielding@avron.ICS.UCI.EDU>
> 
> > 1. In a HEAD response, what should Content-Length be set to?  The
> >    length of the (non-existent) object body, or 0?
> 
> The length of the object-body that would have been returned had
> the request been a GET.

This is not very clear in the description of the Content-Length field
that it describes the length of the object referenced by the URI,
which may or may not be present in the message.  Maybe HEAD should
return the description of the object as the object body of the message
so such ambiguities and overloading dont occur.

> > 2. Is there a view on how locally-time-stamped data should have their
> >    Last-Modified GMT computed?  It's impractical to recreate the
> >    true original GMT time-stamp (as the timezone and daylight savings
> >    regime of the place of last modification is usually unknown).  Using
> >    the current GMT offset will result in the timestamp of some data
> >    jumping forwards or backwards an hour, twice a year, which could
> >    affect caching.
> 
> There are many views as to how this should be done, but none of them
> are within the realm of the HTTP protocol.  All that matters is that
> the date used within the protocol is GMT (UT).  How the date is obtained
> (and, in fact, what it means to be "modified") is entirely up to the
> application sending the object.

Doesnt the lack of a clear meaning of modification make this almost '
useless, except maybe for a matched pair of client and server that
have a common meaning.  It needs to reflect that either the content
as returned is different then previous to the date.  I could also 
reflect metainformation change, such as expiration updated.  But, I
think that is a little too nebulous.

Either way, some agreed meaning needs to be assigned to modified.

Keith
-----------------------------------------
Keith Ball                       Unix/SMTP mail:  kball@novell.com
Building 1                      MHS mail: KBALL@NOVELL
2180 Fortune Drive
San Jose Fortune  (sjf.novell.com)
(408) 577 8428
Fax: (408) 577 5855

Novell, Inc.

-- sent via the LAN WorkPlace Mailer
Received on Monday, 5 December 1994 16:09:52 EST

This archive was generated by hypermail pre-2.1.9 : Wednesday, 24 September 2003 06:31:09 EDT