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Re: ADAMS1, point 31. (cachability of methods).

From: Jeffrey Mogul <mogul@pa.dec.com>
Date: Mon, 16 Nov 98 12:32:03 PST
Message-Id: <9811162032.AA18651@acetes.pa.dec.com>
To: http-wg@hplb.hpl.hp.com
Henrik writes:
>   A caching system MUST NOT treat responses to other methods
>   as cachable (by the definition in section 1.3) unless the
>   response includes Cache-Control or Expires header fields
>   implying that the response is cachable.

    This doesn't work with the wording in section 13.11 which I am
    basing the cache interactions for the M- methods used by the HTTP
    Extensions Framework on:

    ...

    I don't mind that the request to the origin server is made
    conditional but it must not be served without having been forwarded
    to the origin server.

If the origin server is using an extension that does require
write-through, then it shouldn't be sending responses with
something like:
	Cache-control: max-age=12345
which implies cachability.  In the case you're describing, the
origin server has to send something like
	Cache-control: max-age=12345, must-revalidate
or
	Cache-control: max-age=0, must-revalidate
to get the right semantics.

Unless your extension mechanism wants to support extensions
where the origin-server is ignorant of the caching implications
(which seems foolish), then I think we already have the necessary
mechanisms in place, and we shouldn't be adding new restrictions.

-Jeff
Received on Monday, 16 November 1998 20:32:12 EST

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