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Re: PROPOSAL - i109: Clarify entity / representation / variant terminology

From: Jonathan Rees <jar@creativecommons.org>
Date: Fri, 6 Feb 2009 15:56:36 -0500
Cc: Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <00A2AA39-50BA-4AF7-8FA3-6F3C4C430DA4@creativecommons.org>
To: Roy T. Fielding <fielding@gbiv.com>


On Feb 6, 2009, at 2:03 PM, Roy T. Fielding wrote:

> Sorry, that is not true.  There are many resources involved in HTTP,  
> only
> one of which is identified by the requested URI.  Each of those  
> resources
> may have representations, and the meaning of the payload in a  
> response message
> is defined by the status code.  A 404 response is going to contain a
> representation of a resource on the server that describes that error.
> A 200 response is going to contain a representation of the resource  
> that
> was identified as the request target.
>
>> Webarch goes further and says that a 'representation' is 'of' the  
>> resource, meaning that there is a special relationship between the  
>> entity and the resource -- it carries the information associated  
>> with the resource's current state (in the REST sense), or something  
>> like that (a different story for services). This relationship  
>> doesn't hold for requests or non-200 responses. This sort of makes  
>> sense because in the English language a representation always  
>> represents something (is a representation of something).  I'm not  
>> saying there is a reason for HTTPbis to make such a commitment -  
>> that could be considered 'application layer', and any theory of  
>> 'representation' could be left out of the protocol.
>
> I am not aware of any such conclusions in webarch, at least in the  
> one that
> I approved for publication.
>
> ....Roy

Cool!  I guess I did make a logical leap there, assuming that  
'representation' was shorthand for 'representation of the resource  
named by the request-URI'. Never occurred to me it could mean anything  
else.

I always forget that you can CN a 404 entity.

I prefer 'entity', though, as it is more neutral and doesn't lead to  
this confusion. Am I an outlier, or could anyone else make the same  
mistake? Maybe there should be an explanation "representation of what"?

Sorry for adding to the muddle!

Jonathan
Received on Friday, 6 February 2009 20:57:26 GMT

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