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Re: If-Range and cache validation using Last-Modified

From: Roy T. Fielding <fielding@gbiv.com>
Date: Tue, 19 Jul 2011 17:14:17 -0700
Cc: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Message-Id: <957C8792-435D-42A3-B942-3CE97678DD6A@gbiv.com>
To: Matthew Cox <macox@microsoft.com>
On Jun 3, 2011, at 9:16 AM, Matthew Cox wrote:

> Part 5 section 5.3 If-Range has the following text in the case that the response has no etag and only Last-Modified.
>    If a client wishes to perform a sub-range retrieval on a value for
>    which it has only a Last-Modified time and no opaque validator, it
>    MAY do this only if the Last-Modified time is strong in the sense
>    described in Section 2.1.2 of [Part4].
> Section 2.1.2 in Part 4 has this text:
>    o  The validator is about to be used by a client in an If-Modified-
>       Since or If-Unmodified-Since header field, because the client has
>       a cache entry for the associated representation, and
>    o  That cache entry includes a Date value, which gives the time when
>       the origin server sent the original response, and
>    o  The presented Last-Modified time is at least 60 seconds before the
>       Date value.
> This seems to exclude If-Range which is strange since the If-Range text pointed to this section.  Is it possible to add If-Range to the text in the first bullet point, or make the text more generic such that it doesn’t exclude other methods that use the Last-Modified time?

I was in the process of rewriting part 4 the last time I swapped out.
My intention was to remove the reference to If-Range and simply copy the
last two bullets (one sentence) to Part 5.

Received on Wednesday, 20 July 2011 00:14:51 UTC

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