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Re: More small edits to draft 04a

From: Roy T. Fielding <fielding@liege.ICS.UCI.EDU>
Date: Tue, 04 Jun 1996 06:03:31 -0700
To: Jeffrey Mogul <mogul@pa.dec.com>
Cc: jg@w3.org, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Message-Id: <9606040603.aa00544@paris.ics.uci.edu>
>     semantically transparent cache
>       A cache that does not affect the semantics of a request and the
>       resulting response.  A response is considered to be unaffected by
>       the cache when the client receives a response equivalent to what
>       it would have received if it had made the request directly to the
>       origin server.
> 
> I think this leaves the definition of "equivalent" unbound, and omits
> the notion of timeliness.

Is it necessary to bind "equivalent"?  I was thinking in terms of
entity comparison, wherein the origin server sometimes doesn't
require exact equality.  The notion of timeliness is implied by
"if it had made the request directly".

> I do agree that the current wording is awkward and imprecise.  I'd suggest
> 
>    semantically transparent
>       A cache behaves in a "semantically transparent" manner, with
>       respect to a particular response, when its use affects neither
>       the requesting client nor the origin server, except to improve
>       performance.  When a cache is semantically transparent,
>       the client receives exactly the same response (except for
>       hop-by-hop headers) that it would have received had its request
>       been handled directly by the origin server.

Do you really want it defined as no affect on the origin server?
That would make it impossible for any cache to be semantically
transparent because they interfere with demographic collection
(even log forwarding is not enough to avoid that affect).
I think that would make the definition less than useful.


 ...Roy T. Fielding
    Department of Information & Computer Science    (fielding@ics.uci.edu)
    University of California, Irvine, CA 92717-3425    fax:+1(714)824-4056
    http://www.ics.uci.edu/~fielding/
Received on Tuesday, 4 June 1996 06:17:13 EDT

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