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Re: If-Modified-Since No Longer Cool?

From: John W. James <jjames@firstfloor.COM>
Date: Mon, 07 Oct 1996 17:42:08 -0700
Message-Id: <2.2.32.19961008004208.006a7b1c@homeplate>
To: Ari Luotonen <luotonen@netscape.com>, jjames@firstfloor.COM (John W. James)
Cc: www-talk@w3.org (www-talk mailing list)
I looked through the HTTP 1.1 spec (section 14.24), and the only mention
about Last-modified is that you have to be careful of things like clock
synchronization. Is this an "open to interpretation" thing? This wouldn't
seem to indicate to me that you only send back a 304 if the last modified
and IMS dates match.

In most cases I have the date lying around that came from the server. I just
happen to be in a situation this time where I don't have the original date.

        John

At 05:23 PM 10/7/96 -0700, Ari Luotonen wrote:
>
>Use the time string given by the Last-modified date.  The comparison
>is (as per the HTTP spec) an equality-check, not a less-than-or-equal.
>
>-- Cheers, Ari --
>
>> At 02:31 PM 10/7/96 -0700, you wrote:
>> >
>> >> I actually tried the four digit year hooked up to a Netscape Enterprise
>> >> Server and didn't have any luck either. I should have mentioned all the
>> >> formats I tried. I tried using both the long and short form of the day
>> >> string (Mon and Monday), both the long and short form of the year (96 and
>> >> 1996), tried using both dashes and spaces between the date fields
(07-Oct-96
>> >> and 07 Oct 96), 
>> >> and might have tried a couple of other things I can no longer remember.
>> >
>> >In the case of Netscape, this is probably due to our DNS load
>> >balancing, and the filesystem times not being synchronized.  Try with
>> >a fixed homeNN.netscape.com number, where NN is 1..32.
>> >
>> >-- Cheers, Ari --
>> >
>> >> {homeplate 51} telnet splendid-splinter 4040
>> >> Trying 198.206.195.12 ...
>> >> Connected to splendid-splinter.
>> >> Escape character is '^]'.
>> >> HEAD / HTTP/1.0
>> >>  
>> >> HTTP/1.0 200 OK
>> >> Server: Netscape-Enterprise/2.0a
>> >> Date: Mon, 07 Oct 1996 21:06:37 GMT
>> >> Accept-ranges: bytes
>> >> Last-modified: Thu, 29 Aug 1996 19:05:16 GMT
>> >> Content-length: 2863
>> >> Content-type: text/html
>> >>  
>> >> Connection closed by foreign host.
>> >> 
>> >> {homeplate 51} telnet splendid-splinter 4040
>> >> Trying 198.206.195.12 ...
>> >> Connected to splendid-splinter.
>> >> Escape character is '^]'.
>> >> GET / HTTP/1.0
>> >> If-Modified-Since: Monday, 07 Oct 1996 16:00:00 GMT
>> >>  
>> >> HTTP/1.0 200 OK
>> >> Server: Netscape-Enterprise/2.0a
>> >> Date: Mon, 07 Oct 1996 21:08:22 GMT
>> >> Accept-ranges: bytes
>> >> Last-modified: Thu, 29 Aug 1996 19:05:16 GMT
>> >> Content-length: 2863
>> >> Content-type: text/html
>> >>  
>> >> <HTML>
>> >>  
>> >> <HEAD>
>> >>   <TITLE>Enterprise Home Page</TITLE>
>> >> </HEAD>
>> >>  
>> >> ... etc etc etc ...
>> >> 
>> >> 
>> >> At 01:39 PM 10/7/96 -0700, Ari Luotonen wrote:
>> >> >
>> >> >> Are there good reasons I just can't think of for not supporting
>> >> >> If-modified-since in the request? Did I take a nap and miss a format
>> change?
>> >> >> 
>> >> >> GET / HTTP/1.0
>> >> >> If-Modified-Since: Monday, 07-Oct-96 16:00:00 GMT
>> >> >
>> >> >That's one of the older formats.  The best thing to use is the
>> >> >preferred format with full 4-digit year, that is:
>> >> >
>> >> >If-Modified-Since: Mon, 07 Oct 1996 16:00:00 GMT
>> >> >
>> >> >or use blindly the same string as is sent by the server in the Date:
>> >> >header.
>> >> >
>> >> >Cheers,
>> >> >--
>> >> >Ari Luotonen	* * * Opinions my own, not Netscape's * * *
>> >> >Netscape Communications Corp.		ari@netscape.com
>> >> >501 East Middlefield Road		http://home.netscape.com/people/ari/
>> >> >Mountain View, CA 94043, USA		Netscape Proxy Server Development
>> >> >
>> >> >
>> >> 
>> >> ---------------------------------------------------------------
>> >> John James                    Email:  jjames@firstfloor.COM
>> >> First Floor, Inc.             Web:    http://www.firstfloor.COM
>> >> 444 Castro Street, Suite 200  Tel:    (415) 254-5101
>> >> Mountain View. CA 94041       Fax:    (415) 968-1193
>> >> 
>> >> 
>> >> 
>> >> 
>> >
>> >Cheers,
>> >--
>> >Ari Luotonen	* * * Opinions my own, not Netscape's * * *
>> >Netscape Communications Corp.		ari@netscape.com
>> >501 East Middlefield Road		http://home.netscape.com/people/ari/
>> >Mountain View, CA 94043, USA		Netscape Proxy Server Development
>> >
>> >
>> 
>> ---------------------------------------------------------------
>> John James                    Email:  jjames@firstfloor.COM
>> First Floor, Inc.             Web:    http://www.firstfloor.COM
>> 444 Castro Street, Suite 200  Tel:    (415) 254-5101
>> Mountain View. CA 94041       Fax:    (415) 968-1193
>> 
>> 
>> 
>> 
>
>Cheers,
>--
>Ari Luotonen	* * * Opinions my own, not Netscape's * * *
>Netscape Communications Corp.		ari@netscape.com
>501 East Middlefield Road		http://home.netscape.com/people/ari/
>Mountain View, CA 94043, USA		Netscape Proxy Server Development
>
>

---------------------------------------------------------------
John James                    Email:  jjames@firstfloor.COM
First Floor, Inc.             Web:    http://www.firstfloor.COM
444 Castro Street, Suite 200  Tel:    (415) 254-5101
Mountain View. CA 94041       Fax:    (415) 968-1193
Received on Monday, 7 October 1996 20:45:11 GMT

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