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/

Received on Tuesday, 7 October 2003 12:40:26 UTC