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Re: Feedback for draft-nottingham-http-link-header-03

From: Williams, Stuart (HP Labs, Bristol) <skw@hp.com>
Date: Wed, 3 Dec 2008 15:20:26 +0000
To: "mnot@mnot.net" <mnot@mnot.net>
CC: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>, Eran Hammer-Lahav <eran@hueniverse.com>
Message-ID: <233101CD2D78D64E8C6691E90030E5C8245CD7FA50@GVW1120EXC.americas.hpqcorp.net>

Hello Mark,

[just dipping into the achive and found this between you and Eran]

> >>   The context of links conveyed in the Link header field is the
> >>   representation that the header is part of.
> >
> > This makes sense since the header is provided in the context of the
> > representation. However, is there a way to indicate that a link is
> > persistent across representations and is not representation-
> > specific? Do 404 and 303 considered representations?
>
> *sigh* this is the tricky bit; HTTPbis has at least one open issue on
> this. I believe the current position is that all messages have
> entities, and all entities are representations, the trick being that
> the representation isn't always of the resource which the request was
> sent to; sometimes it's an "anonymous" representation.

Oh dear... I think we need to be clear about the whether the relations being conveyed in Link: headers are intended to hold between resources or between the conveyed representation and whatever the target URI refers to.

Personnally, my hope is that the relations are regarded as holding between the resources that are referenced by URIs (as opposed to one party to the relation being a more ephemeral representation or message being conveyed).

Of course the question is what resource supplies the context, particularly in the case of a response that carries a "Content-Location:" header that carries a different URI from that in the request.

It seems to me that candidate choices for the context resource are:

a) the resource referenced in the request line of the corresponding HTTP request.
b) the resource referenced in a Content-Location: header returned in the same response.

are there any other candidates?

Does one take a) as the default and allow b) if present to override a), or simply stick with the original request URI.

Simplicity suggests just a) and that if you want to find out about links associated with the resource reference by a "Content-Location:" then you go ask there.

Regards

Stuart
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Received on Wednesday, 3 December 2008 15:24:54 GMT

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