John,
I have a question about the THREDDS Dataset Inventory Catalog XML. I
don't intend this as a criticism, but rather I'm curious about the
choices and trade-offs. All of us that are messing around with XML are
wrestling with similar issues.
In general, it seems that relationships between elements in the XML are
done via attributes. For example, a <service> element is referred to in
the document via the serviceName attribute in the <dataset> element.
And a <dataset> element can be repeated by referencing the name of
another <dataset> element via the alias attribute.
It seems to me that using this technique then requires that client code
must be written to follow these connections. By contrast, it seems that
the XML community has attempted to create languages (like XPointer) that
would "standardize" these sorts of references. Admittedly, even though
the XPointer recommendation is a year old, I have not found (m)any
implementations in general purpose XML software.
Can you please comment on these choices and trade-offs for defining the
internal connections between bit of XML that went into developing the
Inventory Catalog?
Thanks,
Roland
John Caron wrote:
A proposed new version of the THREDDS Dataset Inventory Catalog is
ready for your comments. Please send them to thredds@xxxxxxxxxxxxxxxx,
or to me.
The new spec was created in collaboration with NCAR's Community Data
Portal group. It adds new types of information for "enhanced catalogs"
to facilitate interaction with search services and digital libraries.
Annotated specification is at:
http://www.unidata.ucar.edu/projects/THREDDS/techNew/catalog/InvCatalogSpec.html
Tutorial (not complete) is at:
http://www.unidata.ucar.edu/projects/THREDDS/techNew/catalog/Primer.html
The new spec is based on XML Schema. The schema is at
http://www.unidata.ucar.edu/schemas/thredds/InvCatalog.1.0.xsd
Changes from version 0.6:
http://www.unidata.ucar.edu/projects/THREDDS/techNew/catalog/Changes1.0.txt
Thanks for any comments on this spec.
