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RE: a protocol analog to abstract/concrete identifiers (and direct metadata access)

From: Dan Connolly <connolly@w3.org>
Date: Mon, 22 Sep 2008 09:15:26 -0500
To: Drummond Reed <drummond.reed@cordance.net>
Cc: 'www-tag' <www-tag@w3.org>
Message-Id: <1222092926.6800.795.camel@pav.lan>

On Mon, 2008-09-22 at 00:03 -0700, Drummond Reed wrote:
[...]
> [1] http://www.hueniverse.com/hueniverse/2008/09/discovery-and-h.html

Thanks for the pointer; that is an interesting read...

> What we're looking for is a solution that provides direct metadata access
> without violating the principles of Web architecture.

Not an easy task. It reminds me of the case of P3P... you want
to know the privacy policy of a resource before you access it,
but in asking what the privacy policy is, you have already
given away at least your IP address...


for reference...

ISSUE-36
siteData-36
Web site metadata improving on robots.txt, w3c/p3p and favicon etc.
http://www.w3.org/2001/tag/group/track/issues/36

It looks like Tim suggested a Metadata: header when he brought
up that issue; I think it's pretty analogous to the Link header
with rel="meta" or the like.

This is the "HTTP Response Header" solution in [1]. Hmm...
I wonder about this:

"Direct Metadata Access - the header is only accessible when interacting
with the resource itself via a GET request."

Oh... there's a separate "HTTP Response Header over HEAD" heading.
Odd...

"HTTP HEAD should return the exact same response as HTTP GET with the
sole exception that the response body is omitted. By adding headers only
to the HEAD response, this solution violates the HTTP protocol and might
not work properly with proxies as they can return the header of the
cached GET request."

I'd expect Link to show up in responses to both GET and HEAD.

By my reading, this meets the "Web Compliant" requirement
and gets as close to "Direct Metadata Access" as
the others that got a + rating.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
gpg D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Monday, 22 September 2008 14:14:55 GMT

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