Configuring the Web Coverage Service

Available WCS datasets are listed in a THREDDS catalog like other datasets. This is not necessarily of much use to WCS clients, who are more likely to expect a WCS Catalog. However it does allow users to find the needed URLs by browsing the catalog, or eventually through a search service. The files can be explicitly named in the catalog, e.g.:

<?xml version="1.0" encoding="UTF-8"?>
<catalog xmlns="http://www.unidata.ucar.edu/namespaces/thredds/InvCatalog/v1.0" 
 xmlns:xlink="http://www.w3.org/1999/xlink" version="1.0.1">
 <datasetRoot path="testwcs" dirLocation="/data/grids/" />
 <service name="wcs" serviceType="WCS" base="/thredds/wcs/" suffix="?request=GetCapabilities&version=1.0.0&service=WCS"/>
 <dataset name="GALEON Test Data">
 <metadata inherited="true">
 <serviceName>wcs</serviceName>
 <authority>unidata.ucar.edu:</authority>
 <dataType>Grid</dataType>
 </metadata>
 <dataset name="striped.nc" urlPath="striped.nc" />
 <dataset name="sst.nc" urlPath="sst.nc" />
 <dataset name="ocean.nc" urlPath="ocean.nc" />
 <dataset name="eta.nc" urlPath="eta.nc" />
 <dataset name="RUC.nc" urlPath="RUC.nc" />
 </dataset>
</catalog>

The files named here all reside in the /data/grids/ directory, named by the datasetRoot element in the service. You can also use a DatasetScan element to serve all the files in a directory tree. See TDS Configuration for details. The only thing you need for WCS is to make the serviceType WCS and the base /thredds/wcs/ . The optional suffix is added at the end of the URL, and forms the WCS GetCapabilities request URL. You may find it more convenient to not include the suffix.

In summary, to enable WCS:

  1. In your configuration catalogs, you must define a WCS service element as above, and indicate whicg datasets should use it.
  2. In the threddsConfig.xml file, set allow to true in the <WCS> element.

Serving Remote Datasets

A slight extension of the WCS Dataset URL format allows the TDS 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 might be

 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
This document is maintained by John Caron and was last updated on Oct 08, 2007