This is a matter of philosophy and practice, I imagine.

One of the reasons I recommend semantic URIs is that the URI represents a clue, if by some chance the web is not available or the information is not served at that URI any more. I think some semantic description should be included in the netCDF file -- on this I agree with Ed.

But I agree with Roy on the bigger picture -- we are building a system that is intended to be long-lived, and in fact much of the web is moving to systems that assume URLs are long-lived. There are a lot of problems that will result if vocabulary servers like Roy's go away.

And the fact is, you just can't store all the metadata in the file -- there is an expanding web of information associated with every observation, and much of that metadata can evolve as our knowledge evolves about the relevant instruments, best calibration values, algorithms, and so on. So we need to allow the ability to reference additional metadata, not just bring it all into every netCDF file (and then update all the files when additional metadata is obtained).

John


On Oct 27, 2009, at 0837, Ed Hartnett wrote:

<[email protected]> writes:

Hello Roy,

That is an interesting idea. There are definitions of these areas on a WWF site, of the form http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0908_full.html where "nt0908" is a tag associated with a particular flag value.

My first thought was:
URI=" http://www.worldwildlife.org/wildworld/profiles/terrestrial/ [flag_meaning]_full.html" with "nt/nt0908" in the flag_meanings attribute, but it appears that the cf-checker does not like having a "/" in flag_meanings. This means we need to either have a more complex syntax, or set up our definition URLs along the lines you suggest.

A more complex syntax might be:
URI=" http://www.worldwildlife.org/wildworld/profiles/terrestrial/ [flag_meaning][0:2]/[flag_meaning]_full.html"

Since the above returns html rather than skos/xml it should perhaps be complemented by a uri_content_type attribute, with value 'html/ text'.

I'll think about the option of setting up something like your vocab server -- or possibly putting some more definitions in the ndg vocab server?

Regards,
Martin

Howdy all!

I really don't think you should store metadata for a file on the
web. Just put it in the file.

Most scientific data are around a lot longer than most URLs. What
happens in 15 years when someone wants to understand this data, and the URL has vanished? It the metadata were stored in the file, then it would
be there for that programmer of the future. (And that programmer may
well be you! <insert scary Halloween laughter here>)

If the metadata seem too large to put in the file, consider storing them in variables, and then use netCDF-4 with compression turned on for those
variables.

Thanks,

Ed



--
Ed Hartnett  -- [email protected]
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I have my new work email address: [email protected]
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John Graybeal   <mailto:[email protected]>
phone: 858-534-2162
Development Manager
Ocean Observatories Initiative Cyberinfrastructure Project: 
http://ci.oceanobservatories.org
Marine Metadata Interoperability Project: http://marinemetadata.org

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