The NetCDF Subset Service (NCSS) is one of the ways that the TDS can serve data. It is an experimental REST protocol for returning subsets of CDM datasets. We want to eventually serve all CDM-compatible datasets through NCSS, but right now there are some restrictions on the types of datasets that are supported.
This documentation is for TDS administrators. If you are a client wanting to access data through the NetCDF Subset Service, look at NetCDF Subset Service Reference.
Enabling NCSS In the TDS
The NetCDF Subset Service must be enabled in the
threddsConfig.xml configuration file before it can be used.
This is done by adding an
allow element to the
NetcdfSubsetService element as follows:
<NetcdfSubsetService> <allow>true</allow> </NetcdfSubsetService>
Serving Datasets With NCSS
In your configuration catalogs, you must define the service like this:
<service name="subsetServer" serviceType="NetcdfSubset" base="/thredds/ncss/" />
Then as usual, add the service to any datasets that you want served, e.g.:
<dataset name="datasetName" ID="datasetID" urlPath="/my/urlPath"> <serviceName>subsetServer</serviceName> </dataset>
Note that the name of the service (
subsetServer in this example) is arbitrary, but the
serviceType and base must be exactly as shown.
Restrictions On What Files Can Be Served
First, only datasets in the format that the CDM can read are supported.
Second, the data must represent one of the following Feature Types:
Verifying A Dataset Is Gridded
Open your file in the ToolsUI program, using the
Any fields identified as grids will show up in the top table.
To be sure, go into the viewer (click to bring up the Viewer, then click again to show the data) and make sure the data is displayed correctly.
If all that works, then the data should be served correctly by the TDS.
Verifying A Dataset Is Pointed
Open your file in the
ToolsUI program using the
In the top table, verify that
featureType is either