Re: [thredds] HTTPServer does not apply NcML changes to your data

On 5/24/2011 5:43 PM, John Maurer wrote:
Aloha TDS Folks,
This is a general word of caution that downloading data via the "HTTPServer" link in TDS does *not* apply any NcML changes. This is a straight download of the files from your disk server without aggregation or alteration of any kind. Although you may have (and in some cases painstakingly so) defined several NcML changes in your config files that make your data CF compliant, add global metadata attributes, or other fixes, these changes only get applied to your data when downloading them via one of the other TDS data services, such as: OPeNDAP, NetCDF Subset Service (NCSS), WMS, or WCS. If you require NcML changes, it is probably best advised to turn off the "http" service in your config file to avoid having two avenues to your archive: one with the changes and one without, which can lead to confusion or difficulties importing your data into other applications. We tend to leave ours on despite this peril for the sake of those users who may not understand how to use OPeNDAP, especially for non-gridded datasets who don't yet have a simple NetCDF download mechanism in TDS like the NetCDF Subset Service. Is there any possibility of modifying HTTPServer to apply NcML in the future? Just curious.
Cheers,
John Maurer
Pacific Islands Ocean Observing System (PacIOOS)
University of Hawaii at Manoa


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Hi John:

Yes, all correct above. HTTP Service is to allow people access to the underlying raw files. We dont modify those files for a number of reasons, partly because they may not be in netcdf-3 (the only format that CDM writes to). The plan is to continue to develop the netcdf subset service, that allows subsetting as well as conversion to netcdf. I realize we need to continue to develop that for non-gridded data.

You might consider putting the HTTPService in a separate catalog if you want to prevent people from getting confused.

John