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Re: Proposed new specification for THREDDSS Catalogs



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 address@hidden, 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.






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