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Re: Netscape 4.5 and HTTP/1.1 Accept-Encoding

From: Ted Hardie <hardie@thornhill.arc.nasa.gov>
Date: Tue, 3 Nov 1998 12:05:19 -0800 (PST)
Message-Id: <9811031205.ZM1740182@thornhill.arc.nasa.gov>
To: Dave Kristol <dmk@research.bell-labs.com>
Cc: http-wg@cuckoo.hpl.hp.com
Dave,
	Content negotiation is hard, ain't it?  I think you
have run into an "infelicity" rather than a true bug, and
that the infelicty is shared between server and client.  It seems
quite likely that the Netscape 4.5 client is using a gzip plugin
or program capable of handling compress, so it would be better
were it configured to send an Accept-Encoding header which
indicated that capability.  The server can't presume that, though,
as someone might have implemented a library which did gzip
encoding but not compress encoding (for licensing or religious reasons).
	The infelicity on the server side is that it is sending
out pre-compressed files in a single format.  In the best of all
possible worlds it would always have the non-compressed format
available, or would be applying the compression on the fly based
on the accepted encodings, or even removing the compression on
the fly.  Since the Accept-Encoding header has a default inclusion
of "No Encoding", that would guarantee that *something* was always
available.
	Not really a bug in either case, just an infelicity.
			regards,
				Ted Hardie


PS.  Today is my last day at NASA; mail will be forwarded, but communication
after November 11th should go to me as hardie@equinix.com

On Nov 3,  2:38pm, Dave Kristol wrote:
> Subject: Netscape 4.5 and HTTP/1.1 Accept-Encoding
> Something interesting has come up that's one of: a bug or infelicity in
> my server, or a bug or infelicity in Netscape 4.5
>
> Netscape 4.5 sends an HTTP/1.0 request with Accept-Encoding: gzip
> header.  A web site has a paper.ps.Z file, i.e., Content-type:
> application/postscript, Content-Encoding: compress.  When NS 4.5 tries
> to GET the paper, my server returns 406 Not Acceptable, because
> "compress" is not one of the accepted encodings.
>
> There seem to be two (not mutually exclusive) conclusions to draw:
>
> 1) Netscape 4.5 should send Accept-Encoding: gzip, compress, because
> gzip (well, the gzip program, anyway) understands the Unix compress
> format.
>
> 2) My server should not send 406, since it's only a SHOULD requirement
> anyway.  Or perhaps it should send 406 only for HTTP/1.1 requests.
>
> Opinions/comments?
>
> Dave Kristol
>-- End of excerpt from Dave Kristol
Received on Tuesday, 3 November 1998 20:06:59 EST

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