W3C home > Mailing lists > Public > public-rdf-dawg-comments@w3.org > June 2005

(Postponed) issue: accessingCollections

From: Danny Ayers <danny.ayers@gmail.com>
Date: Mon, 6 Jun 2005 10:19:54 +0200
Message-ID: <1f2ed5cd05060601191b549915@mail.gmail.com>
To: public-rdf-dawg-comments@w3.org

Good morning,

A post over on redland-dev [1] brought my attention to the current
postponed status of the question of accessing Collections/containers
(even though there appears to be some coverage for Collections in the
draft..?). As and when the issue returns from postponement, I'd like
the following to be taken into consideration.

It's the containers side this post concerns. I can totally understand
avoiding putting anything in place to cover the user-expected
semantics of containers, as opposed to what RDF Semantics covers. So
preservation of the order of an rdf:Seq probably doesn't have a place
in the spec. But to retain some utility, the current behaviour of
Redland seems to work.

Example - an RSS feed contains:

<channel rdf:about="http://www.xml.com/xml/news.rss">
    <title>XML.com</title>
    <items>
      <rdf:Seq>
        <rdf:li resource="http://xml.com/pub/2000/08/09/xslt/xslt.html" />
       ...  
    ...
  ...
<item rdf:about="http://xml.com/pub/2000/08/09/xslt/xslt.html">
    <title>Processing Inclusions with XSLT</title>
 ...

Given a query:

SELECT ?name, ?title, ?x, ?y  WHERE
{ 
 ?channel rdf:type rss:channel .
 ?channel rss:title ?name .
 ?channel rss:items ?x .
 ?x ?y ?item .
 ?item rdf:type rss:item .
 ?item rss:title ?title .
}
 
This will return:  
?name =  "XML.com"
? title = "Processing Inclusions with XSLT"

?x is bound a bnode, y is bound to a resource of the form rdf:_9. 

This kind of access provides the necessary connectivity, and I'd
suggest would do for at least a provisional approach for the spec,
with the proviso that the actual binding of ?y remains unspecified.

I don't know if there a precedent for deprecation by proxy, but it
wouldn't seem unreasonable to me to include a note saying "RDF
implementors intending to use SPARQL should avoid using containers in
their designs".

Cheers,
Danny.

[1] http://lists.gnomehack.com/pipermail/redland-dev/2005-June/000961.html

-- 

http://dannyayers.com
Received on Monday, 6 June 2005 08:20:00 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 8 January 2008 14:14:48 GMT