Ruixin Yang,Menas Kafatos, and X. Sean Wang George Mason University Managing Scientific Metadata Using XML This XML-based distributed system manages scientific metadata in various formats and supports sophisticated search and interactive data-access capabilities. S atellites and other Earth-observing systems produce huge amounts of data at ever-expanding rates. The EOS satellite Terra alone adds more than half a terabyte of data each day, 1 and other Earth-observing platforms and computer weather and climate models produce even more. To use this data in their research effectively, scientists need distributed user-centric information sys- tems with effective search, analysis, and ordering capabilities. A data access and analysis system must let scientific data users find, evalu- ate, access, and use data online regardless of its location or format. A data-delivery mechanism as simple as FTP is useful for data exchange, but its limitations are obvious. The Distributed Oceanographic Data System (DODS, www.unidata.ucar. edu/packages/dods), which enables dis- tributed access to online digital data, is a more sophisticated data-delivery system. When one integrates DODS with the Grid Analysis and Display System (Grads), 2 the resulting GDS 3 lets users define opera- tions performed on the server and obtain the resultant data. However, GDS does not possess enough searchable metadata to let users locate data quickly. In this article, we present our XML- based Distributed Metadata Server (Dimes) 4 — which comprises a flexible metadata model, search software, and a Web-based interface — to support mul- tilevel metadata access, and introduce two prototype systems. Our Scientific Data and Information Super Server (SDISS), which is based on Dimes and GDS, solves accurate data-search and outdated data-link problems by in- tegrating metadata with the data sys- tems. On the implementation front, we combine independent components and open-source technologies into a coher- ent system to dramatically extend system capabilities. Obviously, our ap- proach can be applied to other scientif- ic communities, such as bioinformatics and space science. 52 JULY • AUGUST 2002 http://computer.org/internet/ 1089-7801/02/$17.00 ©2002 IEEE IEEE INTERNET COMPUTING Database Technology on the Web