Hi Roy -
FYI - We're currently experimenting with implementing WCS services, and
the same requirement (wish?) as what you're describing has been raised.
Basically, the need to discover a data set via a cataloging mechanism
(THREDDS, an OGC catalog, a DOD NCES catalog) and then be able to access
it via a WCS that resides somewhere on the network. My initial take on
it is that since WCS data access requests work with unique identifiers
(not URLs), this limits the capabilities of the service in the sense
that the Id-to-resource (data file or db) mapping is managed locally by
the WCS. In other words, the WCS has to 'know about' the resource in
advance of the request, in order to do the mapping.
I think the WCS service should support a mode of operation where a
resource's URL is included in the requests to the service, in order to
support the external WCS concept. I think it is still important to
maintain the Id as a separate entity, so it is not just a question of
using a URL for the coverage identifier, though that idea might be tempting.
The idea needs flushing out a bit, but it is still early enough in WCS's
development that changes like this can be incorporated into the spec via
the OGC working group (my opinion). It definitely seems like it would be
a useful capability to address the situation you describe.
-Oliver
Roy Mendelssohn wrote:
Hi Glenn:
No problem. But we were interested in the general problem, as there
are other datasets which also do not have WCS and which we would like
to add it, rather than trying to get each of them to add it (Some
just have an OPeNDAP server, not a THREDDS server). Yours allowed me
to give Ethan a concrete example so he could look at the catalogs.
Thanks,
-Roy
On Jul 9, 2007, at 7:52 AM, Glenn.Rutledge wrote:
Hello Roy-
That particular dataset will be turned on shortly via WCS. That was
an oversight. Nice to have users telling us where we need stuff!
Glenn
Ethan Davis wrote the following on 7/6/2007 6:02 PM:
Hi Roy,
Looks like you are referencing NCDC catalogs rather than serving the
datasets yourself. So, users would get redirected to the NCDC server
and access the data through the NCDC server. So, as things stand,
NCDC would have to add the WCS service.
You could point to each NCDC dataset with an NcML wrapper and
actually serve the data from your server rather than redirecting to
NCDC. If you did that, you could add the WCS service. However, the
performance wouldn't be as good as direct from NCDC.
I'm afraid I don't know about the WCS request for a time range. So,
I'll leave that for others to answer.
Ethan
Roy Mendelssohn wrote:
Hi Ethan:
I am not certain I follow. To be more specific, look at:
http://oceanwatch.pfeg.noaa.gov/thredds/catalog.html
and scroll down to the datasets " Remote test to Nomads THREDDS
catalog", which is actually on a THREDDS server on an NCDC
computer. They are remotely served through catalogs. Can we add
the WCS service on our end, or will it only work if NCDC adds the
WCS service.
While I have your attention, I have not been able to get a straight
answer if there is a way to send the WCS request to get a time
range, rather than a single time, and if so what is the syntax for
that.
Thanks,
-Roy
On Jul 6, 2007, at 11:24 AM, Ethan Davis wrote:
Hi Roy,
If you are actually serving the dataset through your server (which
it sounds like you are since you mention existing NcML for the
dataset) rather than providing a link in your catalog to the
remote server, I believe you can simply add the WCS service to
your TDS configuration catalog and serve the data via WCS. It
shouldn't require any changes to the NcML, just to the service
element in the catalog.
Of course, this depends on the dataset meeting the WCS server
requirements, e.g., evenly spaced grid.
I'm not sure how it would perform. But I'll leave it for John to
respond on that.
Ethan
Roy Mendelssohn wrote:
Hi:
The question for today is if our TDS is "serving" a dataset
remotely (ie. the remote site has their own TDS and we just link
indirectly to it), can we add a service to our version that they
don't have (just like we can aggregate a remote dataset that is
not aggregated). In particular the remote dataset only has an
OPeNDAP response, but we would like to be able to respond to both
an OPeNDAP and a WCS response.
If we change our NcML appropriately, will that work?
Thanks in advance,
-Roy
**********************
"The contents of this message do not reflect any position of the
U.S. Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097
e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
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--Ethan R. Davis Telephone: (303)
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Software Engineer Fax: (303)
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---------------------------------------------------------------------------
**********************
"The contents of this message do not reflect any position of the
U.S. Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097
e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
--Glenn K. Rutledge
Services Team Leader
Remote Sensing and Applications Division
NOMADS Project Manager
National Oceanic and Atmospheric Administration
National Climatic Data Center
Asheville NC 28801
Phone: (828) 271-4097
Fax: (828) 271-4328
NOMADS: http://nomads.ncdc.noaa.gov/
**********************
"The contents of this message do not reflect any position of the U.S.
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097
e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
===============================================================================
To unsubscribe thredds, visit:
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