Re: Re: Which format?

On Thu, 06 Jan 2005 00:52:50 -0000, Richard Gaskin
<[email protected]> wrote:

> Here's a dumb newbie question:  in the example in section 7 of
> <http://web.resource.org/rss/1.0/spec>, the channel element is show
> disjointed from the items related to it.  Since items are part of a
> channel, I would think it would be more "normal" to nest them within
> the channel tag.
> 
> Am I reading that right?

Arguably the channel-item relationships could have been expressed more
clearly using nesting in the XML doc (assuming it still worked as
RDF/XML). But as it came out the association is made through the use
of URIs in the items list. If you paste the cut-down snippet below
into the RDF Validator (http://www.w3.org/RDF/Validator/) and select
"Triples and Graph" you can see it graphically. The emphasis with RSS
1.0 is generally more towards the model rather than the way it's
passed around in XML syntax.

Whatever the document structure, the use of URIs as identifiers does
offer a huge advantage over, say, the arbitrary strings of RSS 2.0's
<guid>s. Using URIs the items are unambiguously identified as unique
Web resources, which means that you could for example add annotations
to the items in another document on the Web, and those would in effect
be joined to the same (Web-wide) node & arc structure.

This doesn't necessarily mean that the contents of RSS 2.0 feeds can't
be treated in the same structural way, only that the spec doesn't
cover it. You can treat 'Simple' RSS as RDF either by doing a syntax
transformation (there's XSLT for this at [1]) or using a
parser/toolkit that understands the XML dialect, e.g. Raptor [2].

Going the other way, because the syntax of RSS 1.0 is constrained
(compared to RDF/XML in general), you can treat it as yet-another
domain-specific XML format, just like RSS 2.0 etc.

Cheers,
Danny.

[1] http://purl.org/net/syndication/subscribe/feed-rss1.0.xsl
[2] http://librdf.org/raptor/

<rdf:RDF 
  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns="http://purl.org/rss/1.0/">

<channel rdf:about="http://www.xml.com/xml/news.rss">
  <items>
    <rdf:Seq>
      <rdf:li resource="http://xml.com/pub/2000/08/09/xslt/xslt.html" />
      <rdf:li resource="http://xml.com/pub/2000/08/09/rdfdb/index.html" />
    </rdf:Seq>
  </items>
</channel>

<item rdf:about="http://xml.com/pub/2000/08/09/xslt/xslt.html">
<title>Processing Inclusions</title>
</item>

<item rdf:about="http://xml.com/pub/2000/08/09/rdfdb/index.html">
<title>Putting RDF to Work</title>
</item>
</rdf:RDF>


-- 

http://dannyayers.com


 
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