About the GDS

About the GDS

The GrADS Data Server is a stable, secure, easy to install, and easy to configure data server that provides subsetting and analysis services across a network.

The subsetting capability allows a user to request a specified range of time and space from a large dataset, eliminating the need to download everything simply to access a small relevant portion of a dataset.

The analysis capability allows users to retrieve the results of a GrADS operation applied to one or more datasets on the server. Examples of analysis operations include basic math functions, averages, smoothing, differencing, correlation, and regression. This eliminates the need for a client to download large datasets to perform an operation that only generates a small amount of data---instead, the operation is performed on the server, and the small amount of generated data is transferred over the network. Analysis can include previous analysis results and datasets uploaded by the user, as well as datasets hosted on the server.

These services can be provided for any GrADS-readable dataset. Making datasets available on the server is simply a matter of typing in the location of the dataset in the configuration file. Datasets can be added to and removed from the server listings on-the-fly, with no need to restart the server, providing flexibility for data providers whose holdings change rapidly.

In addition, there are a number of parameters to control the performance and resource usage of the server. The central component is a Java servlet, which connects two pieces of pre-exising software: GrADS (see below), which handles the actual data operations; and the OPeNDAP core, which implements the protocol by which information is exchanged with the client across the internet. The Jakarta Project's Tomcat package is used to provide an execution environment for the servlet. All required software is free and open-source, except the JVM implementation in some instances.

For more on GrADS, see the GrADS home page.
For more on Tomcat, see the Tomcat home page.
For more on servlets, see Sun's Java Servlet home page.

What is OPeNDAP?

OPeNDAP (Open-source Project for a Network Data Access Protocol) is a software framework that simplifies all aspects of data networking. OPeNDAP provides tools for making local data accessible to remote locations regardless of local storage format. See the OPeNDAP home page for more information.