Subject: http-link-header in GRDDL

From: "Danny Ayers" <[email-masked]>
Date: Thu, 8 Feb 2007 11:43:00 +0100

re. http://www.mnot.net/drafts/draft-nottingham-http-link-header-00.txt

GRDDL is a set of mechanisms for automatically providing an RDF view
of XML documents. The W3C grddl-wg [1] is aiming to request the
specification, primer and use case documents (drafts linked from [1])
go forward to Last Call on, or soon after the 15th Feb.

A proposal has just been accepted by the GRDDL WG to provisionally
include a mechanism [2] (pasted below) involving the Link: and
Profile: HTTP headers.

Inclusion is contingent on:

* IETF registration of Profile header
* successful test experience

The grddl-wg's charter has the 1st quarter 2007 as the target for
taking the spec to CR, so if anything can be done to expedite the
progress of the link-header draft to RFC it would be most welcome.

(Actions have been accepted to try the mechanism in two different
GRDDL implementations, results of which should be available in the
next few days).

Comments are invited on the GRDDL spec and associated docs through the
public-grddl-comments mailing list, see [1].

Proposed text:
----
Using GRDDL With HTTP Headers

To accommodate XML dialects that do not have the necessary extension
mechanisms in either their schemas or instances we can use HTTP headers
to specify the necessary profile and transformation.

To associate an instance document with a GRDDL transformation include a
Link and a Profile header in the HTTP message. The Link header contains
the URI of the transformation and a "rel" parameter having a value of
"transformation". The Profile header contains the URI of the GRDDL
profile http://www.w3.org/2003/g/data-view

An example HTTP Message

This HTTP message is the response to a request for the document at
http://example.com/doc

HTTP/1.1 200 OK
Date: Tue, 06 Feb 2007 08:34:16 GMT
Content-Length: 35537
Content-Type: application/xml; charset=utf-8
Last-Modified: Fri, 03 Feb 2007 15:00:10 GMT
ETag: "45c3a65a;42380ddc"
Link: <http://www.w3.org/2000/06/dc-extract/dc-extract.xsl>;
rel="transformation"
Profile: <http://www.w3.org/2003/g/data-view>

<?xml version="1.0" encoding="utf-8"?>
<doc>
...
</doc>

----

Cheers,
Danny.

[1] http://www.w3.org/2001/sw/grddl-wg/
[2] http://lists.w3.org/Archives/Public/public-grddl-wg/2007Feb/0020.html

-- 

http://dannyayers.com

---

From: Harry Halpin <[email-masked]>
Date: Sat, 10 Feb 2007 22:53:51 -0500

As the chair of the W3C GRDDL WG, the GRDDL WG has achieved
consensus on the use of "Link" headers and are so supportive of Mark
Nottingham's draft[1] " HTTP Header Linking" that proposes
re-introducing "Link" headers and also "Profile" headers to HTTP 1.1.
GRDDL is a W3C Recommendation stack standard to help convert
HTML/XML/microformats to RDF, and thus very important for the W3C's
future efforts [2], and has received considerable interest from the
wider Web community, being voted the best discussion at the 2006 W3C
Tech Plenary.

       In order for us to include this dependency of HTTP's "Link" and
"Profile" header in GRDDL, we will include these headers as "Features at
Risk." However, if Mark Nottingham's draft does not achieve consensus
and approval we are going to have to drop the feature. So as the W3C
GRDDL WG Chair, I would like to lend my support to Mark Nottingham's draft.

[1] http://www.mnot.net/drafts/draft-nottingham-http-link-header-00.txt
[2] http://www.w3.org/2006/10/grddl-pressrelease

-- 
		-harry

Harry Halpin,  University of Edinburgh 
http://www.ibiblio.org/hhalpin 6B522426