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Re: Atom and RDF

From: Graham Klyne <GK@ninebynine.org>
Date: Mon, 11 Oct 2004 14:58:53 +0100
Message-Id: <>
To: Danny Ayers <danny.ayers@gmail.com>, rdfweb-dev@vapours.rdfweb.org, www-rdf-interest@w3.org, semanticweb@yahoogroups.com
Cc: rss-dev@yahoogroups.com, atom-syntax@imc.org

I think one of the key benefits of RDF is described in this blog-piece by 
DanBri ("missing isn't broken"):


Atom's scope isn't as broad as RDF, so maybe the full-on RDF approach is 
more promiscuous than necessary, but I think it's important, for example, 
to take two or more Atom feeds, possibly containing different and/or 
overlapping information, and compose them in a well-defined way into a 
single feed.  This is what RDF can do.


At 14:19 10/10/04 +0200, Danny Ayers wrote:

>Issues of extensibility and language interop for the Atom Syndication
>Format [1] have been bouncing around the Atom (IETF) group from day
>one. Right now I think discussions may (again) be at a point where
>input from the RDF/FOAF community could be helpful.
>The Atom charter [2] says:
>The format must be able...
>...to represent additional information in an user-extensible manner.
>The Working Group will also take steps to ensure interoperability, by -
>...describing how one migrates from the various RSS versions to the
>Atom syndication feed format.
>There are various dialects in use, but generally RSS syndication
>material comes under the umbrella of either RSS 1.0 or RSS 2.0 (the
>version numbers are only of political significance).
>RSS 1.0 [3] is defined as an RDF vocabulary, with a constrained subset
>of RDF/XML as its exchange syntax (over HTTP), so there's clearly some
>overlap with RDF efforts. RSS 1.0 extensions must follow the
>constraints of RDF. So RDF is at least potentially a factor in Atom's
>user-extensibility and must be a consideration when format migration
>is under discussion.
>RSS 2.0 [4] is defined as a 'simple' XML format. It hasn't got a
>namespace itself, though any material in other XML namespaces can
>appeared in the document and be called an extension. Most syndication
>tools (for publishing and reading) support both formats. Most
>syndication tools only support enough of the RDF model to be able to
>extract the syndication-domain data (there are notable exceptions, and
>of course virtually all RDF tools can consume & process RSS 1.0 out of
>the box). Developers of syndication tools tend to have expertise with
>regular expressions.
>Aside from all else, there is (loosely) a polarization of opinion
>among Atom WG members on how it should tackle extension and interop
>issues, this being roughly parallel to that of RSS 1.0 vs. RSS 2.0.
>One pole is probably most easily expressed by saying Atom should've
>been defined as an RDF/OWL vocabulary and the exchange syntax made
>compatible with RDF/XML.
>The other pole is that Atom Core should be totally bolted down, and
>extensions should simply be partitioned off using XML namespaces.
>There would be no systematic approach to those extensions, anything
>could go anywhere.
>I would guess that group consensus generally leans towards the latter
>pole. (Come to think of it, probably everyone agrees with the
>bolted-down core part).
>In [5] Robert Sayre describes an option for applying potentially
>arbitrary properties to Atom entries in a uniform fashion, which may
>be enough (given a bit of polish) to disambiguate extensions into
>RDF-compatible statements. His suggestion hasn't brought immediate
>condemnation from the core+namespace-only camp. Which is promising.
>But how workable does this seem from the RDF point of view? To me it
>looks like the kind of structural constraint suggested will go a long
>way towards allowing extraction of viable RDF from fairly arbitrarily
>extended Atom documents e.g. using XSLT -> RDF/XML. All the usual
>suspects like FOAF and DC could be used to make richer Atom documents,
>without compromising the core format. Does that sound about right? Or
>wouldn't it work? Or is there a better approach to RDF-compatibility
>that wouldn't worry the simple-XML camp?
>Why does it matter? I think RDF potentially stands to gain quite a lot
>from Atom, in the form of a relatively lightweight but versatile and
>thoroughly spec'ed transport (and editing protocol) which is likely to
>gain widespread deployment. Atom can gain potentially a lot from RDF,
>up front for its intuitions into modelling on the Web and longer term
>through compatibility with (and adoption by) RDF-based systems. Then
>everyone gains when all these systems are joined together...
>[1] http://www.intertwingly.net/wiki/pie/FrontPage
>[2] http://www.ietf.org/html.charters/atompub-charter.html
>[3] http://purl.org/rss/1.0/spec
>[4] http://blogs.law.harvard.edu/tech/rss
>[5] http://www.imc.org/atom-syntax/mail-archive/msg10481.html

Graham Klyne
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Received on Monday, 11 October 2004 15:19:22 UTC

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