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Re: NEW: #225: PUT and DELETE invalidation vs. staleness

From: Yves Lafon <ylafon@w3.org>
Date: Thu, 29 Jul 2010 06:08:18 -0400 (EDT)
To: Mark Nottingham <mnot@mnot.net>
cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-ID: <alpine.DEB.1.10.1007290549160.6474@wnl.j3.bet>
On Fri, 23 Jul 2010, Mark Nottingham wrote:

> <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/225>
>
> p2 7.6 (PUT):
>
> If the request passes through a cache and the Effective Request URI 
> identifies one or more currently cached entities, those entries SHOULD 
> be treated as stale.
>
> p6 2.5 (Request Methods that Invalidate):
>
> Here, "invalidate" means that the cache will either remove all stored 
> responses related to the Effective Request URI, or will mark these as 
> "invalid" and in need of a mandatory validation before they can be 
> returned in response to a subsequent request.
>
> These sections conflict regarding the side effects of PUT; p2 only wants 
> it marked stale, whereas p6 says it cannot be served stale, but must (at 
> least) be revalidated.
>
> The same problem holds for DELETE.

> One point of data: Squid invalidates (i.e., removes from cache) as a 
> side effect of PUT/DELETE, although IIRC this is only in Squid-2.HEAD.
>
> Opinions?

Just checked my implementation, and it marks it as stale, mandating 
revalidation. It is really up to implementation, so p2 should defer to p6 
for the definition of what a cache should do in any case (to remove the 
current conflict), and let implementation decide.

Proposal:
p2:
> If the request passes through a cache and the Effective Request URI
> identifies one or more currently cached entities, those entries SHOULD
> be treated as stale.

=>

If the request passes through a cache and the Effective Request URI
identifies one or more currently cached entities, those entries SHOULD
be treated invalidated (See p6 2.5)

And for p6 change

> Here, "invalidate" means that the cache will either remove all stored
> responses related to the Effective Request URI, or will mark these as
> "invalid" and in need of a mandatory validation before they can be
> returned in response to a subsequent request.

=>

Here, "invalidate" means that the cache will either remove all stored 
responses related to the Effective Request URI, or will mark these as 
stale and in need of a mandatory validation before they can be returned in 
response to a subsequent request.

-- 
Baroula que barouleras, au tiéu toujou t'entourneras.

         ~~Yves
Received on Thursday, 29 July 2010 10:08:20 GMT

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