The THREDDS project is developing middleware to bridge the gap between data providers and data users. The goal is to simplify the discovery and use of scientific data and to allow scientific publications and educational materials to reference scientific data. The mission of THREDDS is for students, educators and researchers to publish, contribute, find, and interact with data relating to the Earth system in a convenient, effective, and integrated fashion.
The THREDDS project consists mainly of two software packages and two related XML encodings:
- the netCDF-Java/CDM library;
- the NetCDF Markup Language (NcML);
- the THREDDS Data Server (TDS); and
- the THREDDS Catalog specification.
Source code for each of these is available from GitHub at
The latest released and snapshot software artifacts (.jar and .war files e.g.) are available from Unidata's Maven repositories
- https://artifacts.unidata.ucar.edu/content/repositories/unidata-releases/
- https://artifacts.unidata.ucar.edu/content/repositories/unidata-snapshots/
Copyright and licensing information can be found here
as well as in the COPYRIGHT file accompanying the software. (??????)
More details on each of these can be found below.
The netCDF Java library implements the Common Data Model (CDM) which provides an interface to netCDF files and other types of scientific data formats.
For more information about netCDF-Java/CDM, see the netCDF-Java web page at
and the CDM web page at
http://www.unidata.ucar.edu/software/netcdf-java/CDM/index.html
You can obtain a copy of the latest released version of netCDF-Java software from
More documentation can be found at
A mailing list, netcdf-java@unidata.ucar.edu, exists for discussion of all things netCDF-Java/CDM including announcements about netCDF-Java/CDM bugs, fixes, enhancements, and releases. For information about how to subscribe, see the "Subscribe" link on this page
For more general netCDF discussion, see the netcdfgroup@unidata.ucar.edu email list.
We appreciate feedback from users of this package. Please send comments, suggestions, and bug reports to support-netcdf-java@unidata.ucar.edu. Please identify the version of the package.
NcML is an XML representation of netCDF metadata, it approximates the header information one gets from a netCDF file with the "ncdump -h" command. NcML is similar to the netCDF CDL (network Common data form Description Language), except, of course, it uses XML syntax.
Beyond simply describing a netCDF file, it can also be used to describe changes to existing netCDF files. A limited number of tools, mainly netCDF-Java based tools, support these features of NcML
For more information about NcML, see the NcML web page at
http://www.unidata.ucar.edu/software/netcdf/ncml/
The THREDDS Data Server (TDS) is a web server that provides metadata and data access for scientific datasets, using a variety of remote data access protocols.
For more information about the TDS, see the TDS web page at
You can obtain a copy of the latest released version of netCDF-Java software from
A mailing list, thredds@unidata.ucar.edu, exists for discussion of the TDS and THREDDS catalogs including announcements about TDS bugs, fixes, enhancements, and releases. For information about how to subscribe, see the "Subscribe" link on this page
We appreciate feedback from users of this package. Please send comments, suggestions, and bug reports to support-thredds@unidata.ucar.edu. Please identify the version of the package.
THREDDS Catalogs can be thought of as logical directories of on-line data resources, encoded as XML documents, which provide a place for annotations and other metadata about the data resources to reside. This is how THREDDS-enabled data consumers find out what data is available from data providers.
THREDDS Catalog documentation (including the specification) is available at