Thematic Real-time Environmental Data Distributed Services (THREDDS)

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The UCAR Unidata program is developing an organizational infrastructure and a software infrastructure, Thematic Real-time Environmental Distributed Data Services (THREDDS), to enable educators and researchers to locate, analyze, visualize, and publish a wide variety of environmental data in both their classrooms and laboratories. The framework for this infrastructure is based on the concept of publishable (data) inventories and catalogs (PICats) and ties together a set of technologies already in use in existing, extensive collections of environmental data that reside on remote, distributed servers. These include client/server data-access protocols from the University of Rhode Island and the University of Wisconsin-Madison, the real-time Internet Data Distribution system from Unidata, the discovery system at the Digital Library for Earth System Education (DLESE), and an extensive set of client visualization tools. Based on the eXtensible Markup Language (XML), metadata in the form of PICats are created in many different ways. Sites receiving real-time environmental data instrument decoders to create PICats describing data products as they arrive. Crawlers can also create PICats by traversing existing retrospective data collections. Since the PICats do not necessarily reside on the server with the data, researchers can create PICats for research publications that point to datasets residing on several data servers. Likewise educators can incorporate PICats of illustrative datasets into educational modules that also include the tools for data analysis and visualization. Students may also use PICats to point to datasets related to their research projects, just as they now use URLs to point to relevant documents. Finally, the text-based nature of PICats allows them to be harvested and indexed in digital libraries not only by current document search engines, but also by specialized tools that make use of the internal structure and semantic content of the PICats. Partial co-funding of this project is being provided by the Division of Earth Sciences in NSF's Geosciences Directorate.