Re: [office-metadata] Any option for a RDF/XML subset?

[Michael Brauer <Michael.Brauer@Sun.COM>]

Hi,

a couple of comments about formal and informal constraints:

First of all, I think we have to differ between constraining the schema 
itself (by providing our own one), or by stating which variants of the 
RDF-XML schema *shall*, *should* or *may* by supported by metadata-aware 
applications. Both will work (and both would be acceptable for me 
personally). I think what's most important at the moment is to reach an 
agreement whether we need some constraints (my impression is that many 
of us think that this is the case), and what they may look like. Whether 
it is better to "implement" them by providing a schema or by providing a 
formal description is something we may decide when we know what 
constrains we do need.

We further have to differ between general constrains (which the RDF-XML 
in ODF has to meet in any case), and use-case specific constrains. So, 
we may not have or may have only a few general constrains, but we may 
have additional constrains (or guidelines) that apply only if an RDF-XML 
instance should be processed with XSLT or XForms.

Regarding the constraints itself: My understanding is that RDF-XML 
supports multiple variants. Unfortunately, I have no experience
- how difficult it is to implement all of them,
- what RDF-XML frameworks exists, and whether they support all variants,
- whether there is a common subset of RDF-XML that is known to work in 
all applications.

What I'm mostly concerned is the implementability of metadata in ODF. If 
it is easy to implement the full RDF-XML specification, then we may not 
need any constrains. But if the RDF-XML specification has variants that 
are difficult to implement or aren't implemented in practice, then we 
should make sure that we find a language (or schema) for ODF that saves 
ODF implementations from implementing these variants.

Michael

Bruce D'Arcus wrote:
> 
> On Feb 13, 2007, at 11:52 AM, Svante Schubert wrote:
> 
>> Considering the time we have left for the complete proposal, I would 
>> rather consider for this version the solution to restrict the included 
>> RDF/XML in the package to a subset of the syntax, as provoking a 
>> normalization and upgrade to a alternative RDF XML metadata standard, 
>> when it becomes available as a standard.
>> Such a normalization could be achieved by a transformation that have 
>> to be written once for ODF applications and might help all XML 
>> processing, therefore seems wort to be considered
>>
>> Do you have a proposal for a RDF/XML subset?
> 
> I worked on this months ago. Spec language and schema is here:
> 
> <http://wiki.oasis-open.org/office/Metadata_Model_and_Syntax>
> 
> However, I no longer favor such formal constraints. Our focus is the RDF 
> model, and I don't think it's our business to be constraining the syntax.
> 
> As a simple example, XMP is also a profile of the RDF/XML syntax (as 
> well as the RDF model). But it's non-standard, and would actually be 
> invalid according to my earlier proposed schema (in link above). So if 
> we foramlly constrain the syntax, we say that XMP is invalid.
> 
> I really think it's enough to offer suggestions for serialziation.
> 
> Curious what John and Dan Brickley think of this.
> 
> Bruce
>