WMS OPENDAP¶
The server can also read data remotely from an OpenDAP service. The same routine applies as given in Create a WMS service on a file, except that you have to provide an OpenDAP url.
For example:
<!-- Layer configuration --> <Layer type="database"> <FilePath>http://opendap.nmdc.eu/knmi/thredds/dodsC/essence/run031/2D_3hrly/temp2_031_2006-2010.nc</FilePath> <Variable>temp2</Variable> <Styles>rainbow</Styles> <Dimension name="time" interval="PT3H" default="max">time</Dimension> </Layer>
After you have added a new dataset, you always need to do:
/data/software/adagucserver/bin/adagucserver --updatedb --config /data/services/config/newservice.xml
Some facts about Opendap¶
- OPeNDAP is the name of the organization and the name of the protocol
- Open-source Project for a Network Data Access Protocol
- Data is stored at remote server
- Data model is similar to NetCDF’s data model (with differences)
- N-dimensional array container, with variables, dimensions and attributes
- Only requested pieces of data are sent
- Accessing small pieces of large files on a remote server can still be quick
- Data is requested based on sub-setting along dimensions
- OPeNDAP resources can be opened locally on your computer as if it were local files using the NetCDF library
- Local files versus remote files is transparent
- The concept of a file is gone, an OPeNDAP endpoint can represent thousands of files aggregated along a dimension
- E.g. Usually concatenate a large time series observation to one endpoint using the time dimension