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Re: I-D ACTION:draft-nottingham-http-link-header-01.txt

From: Phil Archer <parcher@icra.org>
Date: Thu, 20 Mar 2008 17:18:48 +0000
Message-ID: <47E29C78.9000708@icra.org>
To: Alan Ruttenberg <alanruttenberg@gmail.com>
CC: Mark Nottingham <mnot@mnot.net>, www-tag@w3.org

There's a lot of crossover going on here... the discussion about 
relationship types has played out extensively on the IETF/HTTP WG list. 
See, for example, Julian Reschke's comment [1].

Mark's original proposal was to use Link-Profile to make the 
relationship type extensible which seems sensible at first pass, but...

Link: <file.ext1>; rel="rel-1"
Link: <file.ext2>; rel="rel-2"
Link-Profile: <profile.html>

Does the profile define the first or second relationship type, or both?

Link-Prefix would have the same problem but there may be a way through.

Could IANA be the default Link-Prefix? So if that header is absent, OK, 
you know that any relative URI is relative to the IANA namespace.

If supplied, then the prefix URI MUST apply to ALL relationship types, 
even if using one from the IANA namespace - and whatever the namespace 
is should use something like owl:sameAs to map from its own terms to the 
IANA ones - seems a bit wasteful.

Alternatively, we could, perhaps have an id for each Link, something like

Link: <file.ext1>; rel="rel-1"; id="a";
Link: <file.ext2>; rel="rel-2"; id="b";
Link: <my.css>; rel="stylehseet"; id="c";
Link-Profile: <profile.namespace> for="a b";

(i.e. the Profile header would take a space separated list of 
identifiers for the link headers to which it applied. Again, the 
un-qualified relationship type (header c) is from the IANA namespace.


[1] http://lists.w3.org/Archives/Public/ietf-http-wg/2008JanMar/0468.html

Alan Ruttenberg wrote:
> Hi Mark,
> Having the link types be URIs will be a great help in solving a number 
> of issues we've been dealing with around associating metadata with 
> resources.
> I have one suggestion for the document - rather than having the 
> link-extensions, with the default (i.e. not necessarily stated in the 
> headers) base of
> http://www.iana.org/assignments/link-relations.html I would instead 
> either leave that mechanism out, or add something like a Link-Prefix: 
> header that allows one to set a prefix in the way one does for 
> namespaces or RDF serializations.
> Ideally the IANA registry would be served as RDF (perhaps by conneg). In 
> this way, resolution and discovery of relations could be uniform. An 
> agent wishing to discover what
> Link-Prefix: "", "http://www.iana.org/assignments/link-relations#"
> Link: <http://www.cern.ch/TheBook/chapter2>; rel="Previous"
> Would do exactly the same thing as working with:
> Link-Prefix: "dc:", "http://purl.org/dc/terms/"
> Link: <http://mumble.net/~alanr/ThePersonAlanRuttenberg>; rel="dc:creator"
> Regards,
> Alan
> On Mar 19, 2008, at 3:11 AM, Mark Nottingham wrote:
>> See referenced I-D for a rough idea of what I've been kicking around 
>> WRT the Link header with a few people.
>> Note that while it resolves the relation mess, it still has to get 
>> some buy-in by both the HTML and Atom communities, as it asks some 
>> non-trivial things of them.
>> Also, this draft is still rough, with some outstanding issues already 
>> identified. See discussion on the ietf-http-wg list.
>> Cheers,
>> [ note: I've deleted the MIME attachment, because the last time I 
>> forwarded this message, it appeared to crash Mail.app instances that 
>> received it. Oops. ]
>> Begin forwarded message:
>>> From: Internet-Drafts@ietf.org
>>> Date: 18 March 2008 5:30:01 AM
>>> To: i-d-announce@ietf.org
>>> Subject: I-D ACTION:draft-nottingham-http-link-header-01.txt
>>> Reply-To: internet-drafts@ietf.org
>>> A New Internet-Draft is available from the on-line Internet-Drafts
>>> directories.
>>>     Title        : HTTP Header Linking
>>>     Author(s)    : M. Nottingham
>>>     Filename    : draft-nottingham-http-link-header-01.txt
>>>     Pages        : 13
>>>     Date        : 2008-3-17
>>> This document clarifies the status of the Link HTTP header and
>>>  attempts to consolidate link relations in a single registry.
>>> A URL for this Internet-Draft is:
>>> http://www.ietf.org/internet-drafts/draft-nottingham-http-link-header-01.txt 
>>> Internet-Drafts are also available by anonymous FTP at:
>>> ftp://ftp.ietf.org/internet-drafts/
>>> Below is the data which will enable a MIME compliant mail reader
>>> implementation to automatically retrieve the ASCII version of the
>>> Internet-Draft.
>>> ______________________
>>> I-D-Announce mailing list
>>> I-D-Announce@ietf.org
>>> https://www.ietf.org/mailman/listinfo/i-d-announce
>>> Internet-Draft directories: http://www.ietf.org/shadow.html
>>> or ftp://ftp.ietf.org/ietf/1shadow-sites.txt
>> -- 
>> Mark Nottingham     http://www.mnot.net/

Phil Archer
Chief Technical Officer,
Family Online Safety Institute
w. http://www.fosi.org/people/philarcher/
Received on Thursday, 20 March 2008 17:19:33 UTC

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