back to the dataset parameter

[John Caron <caron@xxxxxxxxxxxxxxxx>]

I previously removed the dataset parameter to the WCS server, in favor 
of using the URL path to identify which _local_ dataset to serve.

Now Ive been asked to allow the WCS server to serve remote datasets, eg 
OPeNDAP datasets on another server. For this, I dont see any other good 
way to specify the dataset.

Heres a snippet of some preliminary documentation. Comments welcome. You 
can try this out on motherlode if you want (the example dataset is 
rather large and slow, but pretty).

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A slight extension of the WCS Dataset URL format allows us to serve 
remote datasets. Identify the dataset by adding the parameter dataset 
whose value is a URL:

 http://servername:8080/thredds/wcs?dataset=datasetURL&;

The URL must be a dataset readable by the NetCDF-Java library, typically 
an OPeNDAP dataset on another server. It must have gridded data, with 
identifiable coordinate systems, etc. For example, an OPeNDAP URL is

 
http://las.pfeg.noaa.gov/cgi-bin/nph-dods/data/oceanwatch/nrt/gac/AG14day.nc 


This can be served remotely as a WCS dataset with this URL:

 
http://servername:8080/thredds/wcs?dataset=http://las.pfeg.noaa.gov/cgi-bin/nph-dods/data/oceanwatch/nrt/gac/AG14day.nc&;