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RE: I-D ACTION:draft-whitehead-http-etag-00.txt

From: Larry Masinter <LMM@acm.org>
Date: Thu, 02 Mar 2006 15:18:20 -0800
To: "'Julian Reschke'" <julian.reschke@gmx.de>, "'HTTP Working Group'" <ietf-http-wg@w3.org>, "'WebDAV'" <w3c-dist-auth@w3.org>, discuss@apps.ietf.org
Message-id: <000301c63e4f$988cca60$46832099@corp.adobe.com>

> Jim's draft summarizes the various issues 

Looking through this for the issues, this is what I come up with:

It looks like the HTTP spec doesn't say enough about
ETag headers in 200 and 204 responses to PUT. 

And there is a question, when a HTTP server accepts a PUT
but will modify the octet stream before a subsequent GET
of whether it can return a strong ETag (presumably for
the data it has, not for what was sent).

But doing so wouldn’t be useful -- the client stored
something, but gets back a strong etag for data that it
doesn't have.

So, I'd suggest a couple of things:

(a) any server response for a successful PUT may contain
 an ETag header (200 and 204 as well as 201).
(b) If a strong ETag is returned, then the client can 
   assume that the data was stored exactly as sent.
(c) If the server modifies the data before storing it
  in a way that it cannot guarantee a byte-for-byte
  copy in a subsequent GET, it shouldn't use strong eTags.


Larry
-- 
http://larry.masinter.net
Received on Thursday, 2 March 2006 23:19:12 GMT

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