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Re: Accept headers and media parameters

From: Jim Seidman <jim@rafiki.spyglass.com>
Date: Tue, 5 Sep 1995 14:30:58 -0500
Message-Id: <9509051930.AA29728@rafiki.spyglass.com>
To: Larry Masinter <masinter@parc.xerox.com>
Cc: fielding@beach.w3.org, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
At 11:32 AM 9/5/95 PDT, Larry Masinter wrote:
>Suppose that the definition of application/foobar is such that both
>client and server recognize that anything that is
>application/foobar;version=2.x is also application/foobar;version=2.y
>for y<x. Then you can just accept 2.5 and leave the others implied.

How would something like this be defined?  Is backwards-compatibility
between versions something that goes into the IANA registry when the MIME
type is registered?

Also, a definition such as you describe only helps if that
backwards-compatibility is made clear when application/foobar;version=2.0
comes out.  If you wait until application/foobar;version=2.1 is available,
then an older server wouldn't know that it could send a version=2.0 response
to a version=2.1 request.  Clients would then have to request version 2.0

IMHO, relying on servers to parse and interpret these media parameters is a
very un-robust way of going about this anyway.  Hard-coding the MIME-types
which have backwards compatibility defined for them is a poor solution, and
expecting users to correctly configure this information (e.g.
text/html;version=2.0 can be returned for text/html;version=2.1 or
text/html;version=2.2, etc.) is unreasonable.

Jim Seidman, Senior Software Engineer
Spyglass Inc., 1230 E. Diehl Road, Naperville IL 60563
Received on Tuesday, 5 September 1995 12:33:38 UTC

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