http-link-header in GRDDL


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

An example HTTP Message

This HTTP message is the response to a request for the document at

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: <>;
Profile: <>

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





Received on Thursday, 8 February 2007 10:43:04 UTC