RE: Mapping between schemas

VRA explicitly permits multiple creators, so is modelling choice (a) broken in this context?

If so are you asking whether we need accept VRA data modelled using (a) anyway?  (certainly a change in modelling might be required to support schema evolution...)

- Mick

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> -----Original Message-----
> From: Butler, Mark [mailto:Mark_Butler@hplb.hpl.hp.com] 
> Sent: Tuesday, October 07, 2003 10:40 AM
> To: www-rdf-dspace@w3.org
> Subject: Mapping between schemas
> 
> 
> 
> Hi team,
> 
> After writing an XSLT transform to turn the Artstor XML into 
> RDF/XML, I decided to have a go at writing an RDFS schema for 
> the resulting RDF. I then decided to try to link this schema 
> to an earlier one I had done for VRA Core, because the 
> Artstor metadata is based on VRA Core.
> 
> There are a number of problems doing this, but I came across 
> one which I want to mention here because I suspect it may be 
> potentially very generic. It is the problem where one schema 
> uses properties whereas another schema uses classes.
> 
> For example, consider two schemas that both use the VRA 
> element creator that refers to an image record. Note I am not 
> using RDFS class / property terminology here deliberately, 
> because specifications like VRA Core do not use such terms. 
> Creator has a number of qualifiers, e.g. Creator.Role, 
> Creator.Attribution, Creator.Personal_name, 
> Creator.Corporate_name. So how do we represent this? Well 
> there are two approaches:
> 
> (a) We can create a property called creator, and then 
> subproperties called role, attribution, personal_name and 
> corporate_name. If we do this, we are making the assumption 
> that an image has exactly one creator.
> 
> (b) Alternatively we can create a class called Creator. Now 
> our Image instance has one or more properties called 
> hasCreator, each of which points to an instance of Creator. 
> The properties roles, attribution, personal_name and 
> corporate_name all have domain Creator. Now images can have 
> multiple creators, because each creator is an independent 
> object, rather than a property value. 
> 
> Now lets consider the mapping:
> 
> 1. It's fairly straightforward to map a:role, a:attribution, 
> a:personal_name and a:corporate_name onto their respective 
> counterparts in b.
> 
> 2. Mapping b on to a is may be more difficult, if an image 
> does have multiple creators.
> 
> 3. Mapping between creator is difficult, because it is a 
> property in a and a class in b.
> 
> any thoughts?
> 
> Dr Mark H. Butler
> Research Scientist                HP Labs Bristol
> mark-h_butler@hp.com
> Internet: http://www-uk.hpl.hp.com/people/marbut/
>