| The GrADS Data Server
What is the GrADS
Data Server?
The GrADS Data Server (GDS, formerly known as
GrADS-DODS Server) is a stable, secure data server that provides subsetting
and analysis services across the internet. The core of the GDS is OPeNDAP
(also known as DODS),
a software framework used for data networking that makes local data accessible
to remote locations. GDS services can be provided for any GrADS-readable
dataset: GRIB, Binary, NetCDF, HDF, BUFR, and GrADS station data format.
The GDS unifies all these data formats into a NetCDF framework. The GDS
subsetting capability allows users to retrieve a specified temporal and/or
spatial subdomain from a large dataset, eliminating the need to download
everything simply to access a small relevant portion of a dataset. The
GDS analysis capability allows users to retrieve the results of an operation
applied to one or more datasets on the server. Examples of analysis operations
include basic math functions, averages, smoothing, differencing, correlation,
and regression; the GDS supports any operation that can be expressed in
a single GrADS expression. The GDS is based on Anagram, a modular framework
for high-performace scientific data servers. For more information, please
see the Anagram home page.
What do I need to install
and run a GrADS Data Server?
The GrADS Data Server can run on any
UNIX platform for which both Java and GrADS are available.
- The current release of the GDS is 1.3, and
the software is available here.
- You will also need a Java Virtual Machine (JVM) that supports Java
1.3 or higher. Enter
java -version at the Unix command
prompt to find out what JVM you have currently installed on your system.
The Java Virtual Machine is a free download either from Sun
Microsystems, or your operating system manufacturer's website.
- You will also need GrADS. Because the server uses
some new features in GrADS, you will need version 1.8 or higher. Handling
station data and client uploads requires version 1.9. To take full advantage
of all the features in GDS version 1.3, it is recommended that you use
the latest GrADS release, version 1.9b4. All these versions of GrADS
are available at the GrADS
downloads page.
What's new in the latest
version of GDS?
GDS version 1.3 is now under the GNU public license -- please read the
new COPYRIGHT. The java DAP class library has
been upgraded to version 1.1.7 which implements DAP 2.0. The THREDDS catalog
defaults to version 1.0. GDS version 1.3 also features a complete overhaul
of attribute handling, with additional metadata for gridded and station
data sets. The organization of environment variables and code relating
to disk paths has been updated to support various server resources. See
the README file for a detailed list of improvements.
GDS version 1.2.9 added a new XML-based THREDDS catalog
and support for high-resolution (<= 5km) and large (> 2Gb) data
sets.
GDS version 1.2 and higher does not support the configuration
file format used by GDS 1.1. You can upgrade easily by using this Perl
script to automatically do the conversion: ini2xml.pl
[FTP].
Where is the documentation?
The GDS
documentation includes the User's
Guide, the Administrator's Guide,
the Configuration Reference Page,
and the Source Code Documentation.
A list of some GDS sites:
Reporting GDS problems and
comments
You can report problems/feedback on the GDS three
ways:
1. Post a message to the gradsusr
mailing list
2. Use the "Trackers" on GDS GForge site http://gforge.iges.org/projects/gds/
3. Send an email to www@cola.iges.org
Read more about the GDS
2001 AMS conference proceedings paper entitled
"GrADS
and DODS" by Joe Wielgosz and Brian Doty.
2003 AMS conference proceedings paper entitled
"The GrADS-DODS
Server: An open source tool for distributed data access and analysis"
by Joe Wielgosz, Brian Doty, and Jennifer Adams.
GDS Support
Funding for GDS development and maintenance was
provided by the SIESIP grant from NASA's
Earth Science Information Partnerships. |
