OK, I need to add my two penneth here.
I wrote a short blog entry-like piece last night [1]. My basic point
being that I agree wholly with Ian's analysis but disagree with his
conclusions and I argue the case for a new HTTP status code.
I've taken a keen interest in this kind of thing for a while as it
chimes with the discussion that went on around identifying metadata for
a given resource (which is relevant to the work I did on POWDER).
Metadata discovery was discussed at length in the W3C TAG and is at the
heart of the Web Linking RFC 5988 [2]. That began life many years ago
when Mark Nottingham wanted to bring back the HTTP Link Header (formally).
The formal definition of wdrs:describedby is at [3] and it says:
"The relationship A 'describedby' B asserts that resource B provides a
description of resource A. There are no constraints on the format or
representation of either A or B, neither are there any further
constraints on either resource."
You can use it as the RDF property but it has /exactly/ the same
semantics as the link relationship that we put into the ATOM registry
initially and is now included in RFC 5988. In other words these three
are equivalent (by design)
HTTP
Link: </doc>; rel="describedby" type="foo/bar";
HTML
<link rel="describedby" href="/doc" type="foo/bar">
RDF
<> wdrs:describedby </doc>
This morning I've been mulling over the idea of suggesting a new MIME
type that says "the thing you've asked for isn't an information
resource" and that /might/ help us out of a double round trip to find
RDF about such a thing but even that doesn't really get us past the fact
that 200 means "here's a representation of what you asked for". If I
dereference a URI that identifies beer and it says 200 OK - I at least
expect to be able to drink it, not read about it.
Phil.
[1] http://philarcher.org/diary/303/
[2] http://tools.ietf.org/html/rfc5988
[3] http://www.w3.org/TR/powder-dr/#appD
On 05/11/2010 00:58, Kingsley Idehen wrote:
All,
So when all is said an done, post 303 redirection imbroglio, the moral
of the story *seems* to read as follows:
When you make a hypermedia based Ontology for deployment on an HTTP
network (intranet, extranet, World Wide Web) do include a relation that
associates it with the Properties and Classes that it describes.
Commonly used predicate for this is: rdfs:isDefinedBy [1] .
When you create hypermedia based structured data for deployment on an
HTTP network (intranet, extranet, World Wide Web) do include a relation
that associates each Subject/Entity (or Data Item) with its
container/host document. A suitable predicate for this is:
wdrs:describedBy [2] .
At the current time, most ontologies deployed on the Web do not include
rdfs:isDefinedBy triples. The same applies to descriptor documents (RDF
included) currently deployed on the Web re. wdrs:isDescribeBy.
As a best practice, common use of these predicates would increase
navigability, link density, and overall cohesiveness of the burgeoning
Web of Linked Data. It would truly demonstrate practicing what we
preach, dog-food style!
Links:
1. http://www.w3.org/2007/05/powder-s#describedBy
2. http://www.w3.org/TR/rdf-schema/#ch_isdefinedby.
--
Regards,
Kingsley Idehen
President & CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
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