Re: RDF/XML syntax question - parseType="Collection" plus nodeID

Hi Toby,

first, there is a small confusion in what you write.

There are two kinds of ordered collections: rdf:Seq and rdf:List.

an rdf:Seq looks like that (as the value of property ex:foo)

<rdf:Description><ex:foo>
  <rdf:Seq rdf:node="theSeq">
    <rdf:li><rdf:Descriprion rdf:about="#item1" /></rdf:li>
    <rdf:li><rdf:Descriprion rdf:about="#item2" /></rdf:li>
    <rdf:li><rdf:Descriprion rdf:about="#item3" /></rdf:li>
  </rdf:Seq>
</ex:foo></rdf:Description>

which is equivalent to

<rdf:Description><ex:foo>
  <rdf:Seq rdf:node="theSeq">
    <rdf:_1><rdf:Descriprion rdf:about="#item1" /></rdf:_1>
    <rdf:_2><rdf:Descriprion rdf:about="#item2" /></rdf:_2>
    <rdf:_3><rdf:Descriprion rdf:about="#item3" /></rdf:_3>
  </rdf:Seq>
</ex:foo></rdf:Description>


an rdf:List looks like (as the value of property ex:foo)

<rdf:Description>
  <ex:foo rdf:parseType="Collection">
    <rdf:Description rdf:about="#item1" />
    <rdf:Description rdf:about="#item1" />
    <rdf:Description rdf:about="#item1" />
  </ex:foo>
</rdf:Description>

which is equivalent to

<rdf:Description>
  <ex:foo>
    <rdf:List>
      <rdf:first><rdf:Description rdf:about="#item1" /></rdf:first>
      <rdf:rest rdf:parseType="Resource">
        <rdf:first><rdf:Description rdf:about="#item2" /></rdf:first>
        <rdf:rest rdf:parseType="Resource">
          <rdf:first><rdf:Description rdf:about="#item3" /></rdf:first>
          <rdf:rest rdf:resource="&rdf;nil"/>
        </rdf:rest>
      </rdf:rest>
    </rdf:List>
  </ex:foo>
</rdf:Description>

As you can see, the two are quite different. The main difference is that
nothing prevents an rdf:Seq to be extended (you could add an rdf:_4
property to it), while an rdf:List is closed by the final <rdf:nil>.

So first of all, you should decide if what you need is an rdf:Seq or an
rdf:List.



Now, to answer your question, rdf:parseType and rdf:nodeID are mutually
exclusive, so the quick answer is no.

A workaround would be to explicitly declare the list, with a nodeID, and
use parseTyp in the rdf:rest of the list.

<rdf:Description>
  <ex:foo>
    <rdf:List>
      <rdf:first><rdf:Description rdf:about="#item1" /></rdf:first>
      <rdf:rest rdf:parseType="Collection">
        <rdf:Description rdf:about="#item2" />
        <rdf:Description rdf:about="#item3" />
      </rdf:rest>
    </rdf:List>
  </ex:foo>
</rdf:Description>

Not the most elegant, but it does the trick.

  pa


Toby A Inkster a écrit :
> 
> Little question about using two features of RDF/XML in conjunction. Say
> I have the following RDF/XML:
> 
> <rdf:Description>
>   <ex:foo>
>     <rdf:List rdf:nodeID="theList">
>       <rdf:_1><rdf:Description rdf:about="#i1" /></rdf:_1>
>       <rdf:_2><rdf:Description rdf:about="#i2" /></rdf:_2>
>       <rdf:_3><rdf:Description rdf:about="#i3" /></rdf:_3>
>     </rdf:List>
>   </ex:foo>
> </rdf:Description>
> 
> Now, this can be simplified, removing the rdf:List and rdf:_n stuff,
> using parseType="Collection":
> 
> <rdf:Description>
>   <ex:foo rdf:parseType="Collection">
>     <rdf:Description rdf:about="#i1" />
>     <rdf:Description rdf:about="#i2" />
>     <rdf:Description rdf:about="#i3" />
>   </ex:foo>
> </rdf:Description>
> 
> But note now that the nodeID for the list no longer has an element upon
> which to be hung. If I want to refer to the same list again, I can't
> reference it as a named node. Is there a way around it? Can I use, for
> instance, rdf:nodeID on the <ex:foo/> element?
>

Received on Monday, 24 November 2008 11:08:31 UTC