A standards-based, web services gateway to netCDF datasets

Teams at the Unidata Program Center and University of Florence are working with a number of international partners to implement a web services interface to traditional atmospheric and oceanographic datasets currently stored in netCDF form or served via the OPeNDAP protocol. The project will result in a gateway service using Web Coverage Service (WCS) specification of the Open Geospatial Consortium (OGC). Underneath the WCS interface will be a combination of technologies including THREDDS (THematic Real-time Environmental Distributed Data Services) and HDF5 (Hierarchical Data Format) in addition to netCDF and OPeNDAP. A key component of the project is to develop mechanisms for explicit encoding of coordinate system information in the form of Coordinate System extensions to NcML (the netCDF Markup Language), directly in the data files themselves and in the form of GML (Geography Markup Language) extensions to NcML. These extensions, called NcML-GML, include a subset profile of the standard GML which is in the late stages of adoption by the International Standards Organization (ISO). The WCS interface specification will be developed in the context of an OGC Interoperability Experiment called GALEON (Geo-interface to Atmosphere, Land, Earth, Ocean NetCDF). The paper presents the current status and updated objectives of the project.