Re: [office-metadata] Some implementation drafts aside of RDFa

["Bruce D'Arcus" <bdarcus@gmail.com>]

We chatted about this off-list, but just to summarize (Elias, feel  
free to correct me if I'm off and you're there) ...

On Dec 12, 2006, at 11:44 AM, Svante Schubert wrote:

> After a discussion with Michael and Lars, let me bring in some  
> other implementation details than RDFa.
>
> There are various implementations.
> The earlier used is adding the meta:class attributes for each  
> element, which has meta data. more than one metadata is attached to  
> the same element, the attribute value might be a list of space  
> separated values.
> Another approach is quite similar to the first, but uses user given  
> names as attribute names in conjunction with the meta namespace:  
> 'meta:participant'.
> And the third is adding to each ODF element which has meta data an  
> xml:id and bundle these with an indirection similar to the XForms  
> binding to RDF.
>
> <text:list xml:id="meta1">
>  <text:li xml:id="meta2">Jane Doe</text:li>
>  <text:li xml:id="meta3">John Smith</text:li>
> </text:list>

I think you're confusing the issues here. I'd prefer to talk about  
the model (the RDF triples) and how to bind statements to content nodes.

The xml:id attribute provides a generic mechanism to identify a  
content node as an addressable *resource* (remember, resource and  
properties), so statements may be attached to it externally.

If we have a table with an xml:id attribute value of "table-1", then  
it allows you to do:

<rdf:Description rdf:about="content.xml#table-1">
   ... statements ...
</rdf:Description>

... or do to do from outside the package using an absolute URI.

The meta:about attribute is way to attach statements about other  
resources to a content node (this is where I'm a little unsure of the  
language).

See:

	<http://www.w3.org/2001/sw/BestPractices/HTML/2005-rdfa- 
syntax#id0x1dfedc80>

> Note: If you want mnemonic xml:id values, there should be certainly  
> an API to set them, but this is currently out of scope

Correct.

> In the new meta.xml, let's call it xmeta.xml, we have a binding  
> element similar to the XForms binding, forming the various xml:id's  
> to a set.
>
> <meta:bindings xml:id="binding1">
>    <meta:binding nodeset="content.xml#xpointer(id('meta1'))"/>
> </meta:bindings>
>
> <meta:bindings xml:id="binding2">
>    <meta:binding nodeset="content.xml#xpointer(id('meta2'))"/>
>    <meta:binding nodeset="content.xml#xpointer(id('meta3'))"/>
> </meta:bindings>
>
> Where binding1 and binding2 would be the subject of the RDF.

This seems a needless complication. The subject of a statement is the  
node as identified by the xml:id or the meta:about attribute.

<text:table xml:id="table-1">...</text:table>

If you want to add statements to it, just add them to the package.

It's really that simple. I don't see the value for the redirection.

> Question: How is validation being added? If I want to ask if for  
> example to document being an invitation has the required data and  
> location?

I see different options if you need to do datatyping.

1) you add a datatype attribute to the content node directly
2) you include it in the package

So imagine you have a property called ex:date. Perhaps you have a  
little configuration file along with your plug-in that gives the  
information; maybe the actual RDF/OWL schema:

<owl:DatatypeProperty rdf:about="http://ex.net/event#date";>
   <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#date"/>
   <rdfs:label xml:lang="en">date</rdfs:label>
</owl:DatatypeProperty>

You have something else that says the property is required. When the  
user selects the property there (in their UI they just see the label  
"date" if it's English), they get presented a little date pop-up to  
enter it.

That then looks like this in the XML:

	<text:span meta:property="http://ex.net#date";  
meta:content="2007-01-10">January 10, 2007</text:span>

I dunno; somthing like that. RDFa here actually helps you validate  
the datatype of the content precisely because you are binding a  
statement to specific content.

Bruce