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Re: Reviving HTTP Header Linking: Some code and use-cases

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 11 Mar 2008 12:22:32 +0100
Message-ID: <47D66B78.3040807@gmx.de>
To: Harry Halpin <hhalpin@ibiblio.org>
CC: ietf-http-wg@w3.org

Harry Halpin wrote:
> ...
>> So when defining new link relations, I think it's wise to do so in a
>> way that doesn't rely on profiles.
> That's a very good point. What our code currently does is, if it sees a
> single GRDDL Profile header, then it assumes all the Links might be to
> GRDDL transforms. Ditto with multiple Profiles. If it does not see a
> GRDDL Profile header, we don't follow the Link header URIs.  While it's
> not exact disambiguation (which would be better, but I cannot see how
> that would be accomplished without demanding a 1:1 relationship between
> Profiles and Headers, which would disturb some other use-cases), it
> gives one a smaller space of possible URIs to "follow-our-nose", and
> does disambiguate if only one Profile URI or one Link URI is given.
> In essence, a GRDDL Profile URI is about the best message one can give
> that the author intends the page to be GRDDL'ed. A Link with a GRDDL
> transform is also by itself a pretty good message, but not great, since
> the author may just be using something like microformats but does not
> want their page to have a RDF version. In our spec, we call it author
> "licensing" the GRDDL transform.
> e say it is possible for non-licensed transforms to be followed, but
> they may not preserve the meaning that the author of the document
> intends and thus are inherently not safe.
> ...


So as far as I understand you have two sorts of GRDDL transforms, a 
"licensed" one, and another one.

Why don't you just define two separate link relations then, avoiding the 
Profile stuff?

> Since Link is already approved in an earlier RFC and could be used for
> all sorts of things (i.e. currently there is large discussion of using
> it to distinguish between different types of SemWeb resources in
> www-tag, etc.), we don't "follow the link" looking for a GRDDL unless it
> has the GRDDL Profile URI specified in the HTTP Header.
>> BR, Julian
>> PS: I'm really trying to understand whether Profile is going to help
>> here.
> Thanks for your time and patience. I'm just trying to describe what we
> currently do. We can change if it necessary, but we thought HTTP folks
> would at least want to know. We thought Profile and Link were a good
> combo together.

Of course this kind of input is extremely useful, in particular given 
the fact that the WHATWG crowds has removed profile (which I think is a 

So, let's rephrase this: if a link relation could be a URI (or IRI), 
would we need Profile?

BR, Julian
Received on Tuesday, 11 March 2008 11:22:53 UTC

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