THEMATIC REAL-TIME ENVIRONMENTAL DISTRIBUTED DATA SERVICES (THREDDS) AND THE DIGITAL LIBRARY FOR EARTH SYSTEM EDUCATION (DLESE): FACILITATING PUBLICATION, DISCOVERY AND USAGE OF EARTH SYSTEM DATA

Unidata recently received word that its THREDDS (THematic Real-time Environmental Distributed Data Services) initiative would become part of the NSDL (National Science, Math, Engineering, Technology Education) sponsored by the National Science Foundation.

The overarching goal of THREDDS is to provide students, educators, and researchers with coherent access to a large collection of real-time and archived data sets from a variety of environmental data sources at a number of distributed server sites. The data sets will be conveniently accessible from an collection of THREDDS-enabled data analysis and display tools. THREDDS will provide real-time data delivery via reliable, event-driven "push" technology as well as transparent access to data sets using "pull" systems that make it possible to access data on remote servers as if they were on the users' own computer. The system will be built on a set of software components and data servers that are already in operation or under development.

The heart of THREDDS is metadata contained in publishable inventories and catalogs (PICats). The creation, publication, and distribution of PICats will be facilitated by the discovery system and services provided by DLESE. For example, Sites receiving real-time environmental data can create PICats automatically using decoders and crawlers to create PICats describing data products as they arrive. On the other hand, since PICats do not have to reside on the server with the data, researchers will be able to create PICats for online publications that point to datasets residing on several data servers. Similarly educators will incorporate PICats of illustrative datasets into educational modules that also include tools for data analysis and visualization and students will be able to use PICats to point to datasets related to their research projects, just as they now use URLs to point to relevant documents.

This paper presents an overview of THREDDS and an update on the current status.