How does inheritance work in XML document instances and how do searches know about that inheritance?

Hi,

I'm working on an implementation of the ISO 19115 Metadata Standard.  I know
that ISO 19139 is an W3C XML Schema implementation of ISO 19115.  What I want
to know is how does inheritance work with XML document instances and how do
searches know about that inheritance?

In this example I am using elements from the ISO 19139 XSD but it seems to me
that it doesn't matter what XSD is used.  If it allows inheritance then there
must be a way for XML document instances to know the content of its parents.


For example, An XML metadata record for a "Series" hierarchical Level will
contain information about:
organisation, 
abstract, 
bounding coordinates, 
etc.  
An XML metadata record for a "Dataset" hierarchical Level for that "Series"
will inherit some of these elements and will probably have the content of
other elements filled in.  For example; 
the abstract will be different, 
the attribute accuracy will be added, 
other information will stay the same.

This would indicate that the parent (Series) XML record should be the
authoritative list for the organisation and bounding coordinates.  It also
has content in the abstract but because the abstract is redefined in the
child (Dataset) XML record then the content of the child's abstract
overwrites the content of the parent's abstract.  Are you still with me? ;--)

When this is implemented.  Does the child (Dataset) XML record contain the
content of the organisation and bounding coordinates in the actual XML record
or does it use something like the "import" element to refer to the content of
those elements?  

If it is the former how does the child (Dataset) XML record obtain any
changes made to the parent (Series) XML record?

If it is the latter how does an index of the child (Dataset) XML record know
about the content of the parent's (Series) elements when someone is searching
for those documents?  If the content of the parent's elements are not part of
the index of the child then any search for the parent's elements, eg.
organisation, will not return the child record.

I hope that this is clear enough to define my problem. 

Thanks.


John Hockaday
Geoscience Australia
GPO Box 378
Canberra ACT 2601
(02) 6249 9735
http://www.ga.gov.au/ 
john.hockaday\@ga.gov.au

Received on Friday, 29 April 2005 00:34:36 UTC