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Re: Confusion about Collections

From: Garret Wilson <garret@globalmentor.com>
Date: Sun, 12 Jan 2003 09:23:45 -0800
Message-ID: <3E21A4A1.7060003@globalmentor.com>
To: fmanola@mitre.org
Cc: Shelley Powers <shelleyp@burningbird.net>, www-rdf-comments@w3.org

Frank,

Frank Manola wrote:
> Shelley Powers wrote:
>>Clarification on this, Frank: there is a strong mapping between the RDF/XML
>>of the Container and the generated graph, but almost no mapping at all
>>between the Collection RDF/XML and the generated graph. One could say that
>>the Collection is the ultimate RDF shortcut. This is going to cause
>>confusion, particularly as people try and figure how to programmatically
>>access a 'Collection'. (N-Triples of the graph might help with that.)
>>
>>Wouldn't be a good idea to show the 'long form' of the Collection, as
>>tedious as it is, in addition to the short form? With this, then people can
>>see for themselves the mapping. They'll be able to take the steps that get
>>them from Point A to Point B.
> 
> I need some clarification about your clarification.  I understand what
> you say about the mapping between the RDF/XML of the collection and the
> generated graph (there is one;  it's described in the Syntax
> specification, but reading it isn't for the faint of heart), and I'm
> concocting some words to try to describe it.  However, I'm not sure I
> understand what you mean by the "long form" of the Collection.

Simple: the long form would be, for example (from the primer):

   <rdf:Description rdf:about="http://example.edu/courses/6.001">
     <s:students>
       <rdf:Description>
         <rdf:type="&rdf;List"/>
         <rdf:first="http://example.edu/students/Amy"/>
         <rdf:rest>
           <rdf:Description>
             <rdf:type="&rdf;List"/>
             <rdf:first="http://example.edu/students/Tim"/>
             <rdf:rest>
               <rdf:Description>
                 <rdf:type="&rdf;List"/>
                 <rdf:first="http://example.edu/students/John"/>
                 <rdf:rest>
                   <rdf:Description>
                     <rdf:type="&rdf;List"/>
                     <rdf:first="http://example.edu/students/John"/>
                     <rdf:rest rdf:resource="&rdf;nil"/>
                   </rdf:Description>
                 </rdf:rest>
               </rdf:Description>
             </rdf:rest>
           </rdf:Description>
         </rdf:rest>
       </rdf:Description>
      </s:students>
   </rdf:Description>

Note that this "long form" doesn't show that each referenced student has 
an rdf:type of s:student. Maybe the example should just use 
rdf:Description for each Collection node.

 > It seems
> to me that the graph is the "long form" (that is, it shows the consed
> list, in all its "glory"), and there's a drawn graph in the Primer.  Are
> you saying that a *triples* version of that graph would be clearer, and
> would help people more than the drawing (he asked in astonishment)?  If
> so, do you mean in addition to or instead of the drawing?

Not the graph, not the triples---the long form of the RDF+XML 
serialization. (Of course, the graph is very useful, too.)

Garret
Received on Sunday, 12 January 2003 13:31:57 GMT

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