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Re: terminology question

From: Roy T. Fielding <fielding@kiwi.ics.uci.edu>
Date: Tue, 06 Apr 1999 06:52:48 -0700
To: jschroeder@becomsys.de
Cc: http-wg@hplb.hpl.hp.com
Message-Id: <9904060652.aa23416@paris.ics.uci.edu>
>After reading the spec for a while I suspect that
>every possible entity from a given resource is a
>"variant" and if content negotiation comes into play
>it is termed "representation" as well. 

Nope, that's backwards.  Each possible entity from a resource is
a "representation" of that resource at the time the message originated.
A representation is a variant if, at origination time, the set of
possible representations has a membership greater than one.  It is called
a variant because the chosen representation varies based on the request
parameters (content negotiation).

>If I have a document that changes only over time (eg CGI output), then
>are the different entities termed as different "variants"
>of the same resource as well? Or is it only sensible at a given
>instant? Is there any practical explanation available?

A resource is a mapping function based on time, so its value set is
based on the given instant.

A more extensive explanation is in my web architecture paper (submitted
to ESEC/FSE99, so I can't give people a copy right now).

Received on Tuesday, 6 April 1999 14:58:45 UTC

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