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Re: Clarification on cacheability

From: Roy T. Fielding <fielding@kiwi.ICS.UCI.EDU>
Date: Wed, 22 Dec 1999 11:54:38 -0800
To: "Josh Cohen (Exchange)" <joshco@exchange.microsoft.com>
cc: "HTTP-WG (E-mail)" <http-wg@hplb.hpl.hp.com>
Message-ID: <199912221154.aa11963@gremlin-relay.ics.uci.edu>
>So, my question essentially comes down to this:
>If I invent a new 3xx status code, or overload an existing 3xx
>code but I include a cache-control: header to explicitly
>allow caching, can a cache cache the results?

Only if the cache recognizes (understands the semantics of) the
new status code.

Rationale: Consider the addition of the 206 status code (partial content).
The contents are cacheable, but only by a cache that understands that
the contents are a splice of the cacheable content and not the content
itself.  Thus, unrecognized status code responses must not be cached,
regardless of the presence of cache-control, since the contents of
cache-control are intended for those recipient that do recognize the code.

BTW, this is what you want for the WAP answer.  If they try to use anything
other than a 3xx, they are on their own.

....Roy
Received on Wednesday, 22 December 1999 19:55:45 EST

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