Roland Schweitzer wrote:
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
Hi Roland:
<excuse> Sorry its taken me so long to answer this </excuse>
Anyway, its not clear that the XPointer spec will become an official
standard. XPath seems useable though, and i am open to it. Both the
serviceName and the alias = dataset ID are more or less the simple case
of XPath using IDs. I think using IDs for datasets is so useful that it
should probably be required. Which I would do if we could do so and
still allow the minimal datasets like the DODS File Server. This ID
reference is so simple that even DTDs have it.
So Id say full XPath is a bit of overkill right now, but i am open to
using it in the future. Do you forsee any new features that might need it?
