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

From: Williams, Stuart (HP Labs, Bristol) <skw@hp.com>
Date: Thu, 4 Dec 2008 20:13:41 +0000
To: Eran Hammer-Lahav <eran@hueniverse.com>, Mark Nottingham <mnot@mnot.net>
CC: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Message-ID: <233101CD2D78D64E8C6691E90030E5C8245CDEB576@GVW1120EXC.americas.hpqcorp.net>

Hello Eran,

> -----Original Message-----
> From: Eran Hammer-Lahav [mailto:eran@hueniverse.com]
> Sent: 04 December 2008 17:32
> To: Williams, Stuart (HP Labs, Bristol); Mark Nottingham
> Cc: ietf-http-wg@w3.org
> Subject: RE: Feedback for draft-nottingham-http-link-header-03
>
> > From: Williams, Stuart (HP Labs, Bristol) [mailto:skw@hp.com]
> > Sent: Thursday, December 04, 2008 8:44 AM
> >
> > If you take the view, which I think is the correct view - and I think
> > that you do to, that the links being claimed at least in a response,
> > are between the requested resource and the resource targetted by the
> > link, the question of which representation is taken as "canonicial" or
> > in some sense 'supreme' becomes immaterial.
>
> [It takes a while to get used to my style, but while I
> usually talk in absolutes, there are very few things I have
> strong opinions on (this is not one of them). I'm also really
> new to web architecture (I served a 10 year term in
> investment banking before I escaped to a web job).]
>
> The 'canonical' question doesn't apply if you take the view
> that link is between resources and not representations.

So for the sake of this exchange lets just stipulate this to be the case for now (that relations are between resources)...

> But
> it becomes an implementation concern when building an
> application that defines links to be between resources, and
> the Link header is not fully compatible with that.

You'll have to unpack that some more for me to understand unless all your saying is that the Link header draft needs to be updated in line with what we have just stipulated (a few lines above). ie. is there a "But..." if the Link Header draft stated that the header claimed relations are claimed (we'll leave by what or whom asside) to hold between resource pairs?

> Resource
> discovery (XRDS, POWDER, OpenID, etc.) depends on links
> having a resource and not representation context. But again,
> there are easy implementation-based solutions if the spec
> goes the representation way.
>
> I prefer to define links as between resources regardless of
> their representation mostly for the following reasons:
>
> 1. I think links should be symmetric and 'representation -->
> resource' isn't symmetric. 'resource --> resource' is nice and clean.
> 2. If a 'rel' link is defined as 'representation -->
> resource' that forces 'rev' to be 'resource -->
> representation'. It means that 'B --(rev)--> A' has nothing
> to do with 'A --(rel)--> B' because each is between different
> objects (resource / representation).
> 3. The other way to accomplish symmetry is 'representation
> --> representation' which has been rejected here before. That
> would shift the meaning of 'type' from a hint to an actual
> part of the relationship context (needed to define the
> representation of the linked resource in context for the link).

Yes... I think those three points also make the case quite nicely.

> There are clear implications for defining link as
> 'representation --> resource' vs. 'resource --> resource'.
> One of them is the impact of the definition of the 'rel/rev'
> relationship. All I am asking for is clarity.

I'd be interested to know whether we have persuaded Mark (yet)... Mark?

> EHL

Stuart
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Received on Thursday, 4 December 2008 20:18:37 GMT

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