Web-based access to distributed high-performance geographic information systems for decision support

A number of applications that use GIS for decision support can potentially be enhanced by the use of high-performance computers, broadband networks and mass data stores. We describe our efforts in integrating together these powerful resources to provide useful services to Web-based clients for applications including environmental analysis for agricultural planning and land management; analysis of satellite and photo-reconnaissance images for national defence; and emergency services planning and response. Many decision support applications that manipulate spatial data involve operations on very large data sets internally, which may require the use of high-performance compute servers, but carry out data reduction operations to provide summarised information to the end user. We have investigated the consequences of connecting high-performance resources together with broadband networks, but providing user access at the modest network capabilities or a modem link via the World Wide Web. A range of technologies exist to manipulate spatial data and to integrate modules together. We focus on Web, Java and CORBA technologies and discuss the issues we have encountered in implementing prototype distributed geographic information systems incorporating "active" digital libraries, which provide remote data processing as well as remote data access.