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Re: Link header is representation metadata?

From: Nathan <nathan@webr3.org>
Date: Sun, 06 Mar 2011 15:54:45 +0000
Message-ID: <4D73AE45.9090903@webr3.org>
To: Jonathan Rees <jar@creativecommons.org>
CC: "Roy T. Fielding" <fielding@gbiv.com>, Mark Nottingham <mnot@mnot.net>, Julian Reschke <julian.reschke@gmx.de>, HTTP Working Group <ietf-http-wg@w3.org>
indeed, there seems to be a bit of confusion now on whether a rel is 
between a two resources (in both RFC 5986 and HTML5, or a representation 
and another resource, one example of the latter would be rel=stylesheet 
- I won't even get in to the combination rels like alternative or the 
annotation ones like nofollow!


Jonathan Rees wrote:
> But if you look at RFC 5988, most of the relations seem to be
> *resource* relations, not representation relations. The introduction
> speaks of "relationships between resources"; also
>    "links between resources
>    need not be format specific; it can be useful to have typed links
>    that are independent of their serialisation, especially when a
>    resource has representations in multiple formats."
> So it's a bit confusing to say that Link: is an entity-header (which,
> I admit, 5988 does). I guess a "next" Link: on a 404 response would
> tell you what the next resource is after one that the representation
> carried in the 404 response is a representation of, not the next one
> after the requested resource (which may still exist somewhere).
> This rules out one application I really wanted to use Link: for, which
> is to use it with a 301 or 302 response to give information about the
> resource identified by the URI. You could call this a "value-added
> redirect". With this interpretation it would refer to some resource of
> which the entity in the redirect response was a representation - a
> very different beast.  Oh well!
> Jonathan
> On Tue, Feb 1, 2011 at 4:24 PM, Nathan <nathan@webr3.org> wrote:
>> Roy T. Fielding wrote:
>>> On Feb 1, 2011, at 11:50 AM, Nathan wrote:
>>>> Julian Reschke wrote:
>>>>> On 12.10.2010 01:02, Nathan wrote:
>>>>>> I'm looking for a quick bit of guidance on whether the Link header
>>>>>> would
>>>>>> class as representation metadata
>>>>> The Link header spec says "entity header", which is the terminology we
>>>>> used in HTTPbis until draft 10; so I think it's supposed to fall into the
>>>>> same class as "Content-Language", for example.
>>>> Sorry but I need to come back to this one, can I get a definitive answer
>>>> (please :)) on whether the Link header is representation metadata (like
>>>> Content-Type), or not?
>>> It is sometimes metadata. Some of those times it is representation
>>> metadata, like Content-Type, whereas in other times it can be
>>> resource metadata, like Vary.
>>> And occasionally it is just part of the representation, though that
>>> tends to confuse people who think data == body and headers == meta.
>>> What the link is for depends entirely on the rel value.
>> Thanks Roy, that's exactly the answer I was hoping for!
>> Best,
>> Nathan
Received on Sunday, 6 March 2011 15:56:25 UTC

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