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Re: terminology question

From: Roy T. Fielding <fielding@kiwi.ics.uci.edu>
Date: Sat, 10 Apr 1999 15:08:07 -0700
To: Koen Holtman <koen@win.tue.nl>
Cc: jschroeder@becomsys.de, http-wg@hplb.hpl.hp.com
Message-Id: <9904101508.aa26511@paris.ics.uci.edu>
>>> Nope, that's backwards.  Each possible entity from a resource is
>>> a "representation" of that resource at the time the message originated.
>
>The best way to think of an entity, in my opinion, is to consider it
>to be a _copy_ of a representation which was made at some time.  A
>representation exists internally in a server.  An entity exists in a
>HTTP response (or request).

The representation is the information you get when the entity is
extracted from the HTTP message -- it is the data transferred, not
the internal machine representation on the server.

>>> A representation is a variant if, at origination time, the set of
>>> possible representations has a membership greater than one.
>
>No, this is not how the 1.1 spec defines it.  I would say that in 1.1,
>'representation' and 'variant' are synonymous terms.  A cut-and-paste
>of the definition:
>
>   variant
>      A resource may have one, or more than one, representation(s)
>      associated with it at any given instant. Each of these
>      representations is termed a `variant.' Use of the term `variant'
>      does not necessarily imply that the resource is subject to
>      content negotiation.
>
>All this means that the term 'variant' is not very useful when
>defining details of content negotiation.

No, it means the definition in the spec is wrong, as I said a couple
hundred times in our teleconferences.  You cannot make a wrong thing right
just because I was outvoted.  These are terms defined by the architectural
model of the Web, not defined by HTTP.

....Roy
Received on Saturday, 10 April 1999 23:11:41 EDT

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