A multi-tier framework for accessing distributed, heterogeneous spatial data in a federation based EIS

In the last nine years an integrated EIS (Environmental Information System) has been developed in the State of BadenWürttemberg, Germany, managed by the Ministry of Environment and Transport. As technologies has improved, the basic architecture of the EIS has been revised from a centralized to a distributed system based on the concept of services and objects. The main reason for this redesign was that environmental questions touch a large number of fairly different knowledge domains. These questions are normally addressed by different systems, which are usually heterogeneous, both technical and semantical. Geo-spatial data and GIS components play a leading role in any EIS and have to be integrated into various systems of the EIS. This is a difficult task, since in practice several geospatial data formats and various GIS systems are in use. Therefore a framework (named GIStermFramework) has been developed that allows the integration of GIS components into systems or service based architectures and hide the distributed, heterogeneous geo-spatial data sources. The components of that framework provide a system and data abstraction that use concepts of the upcoming OpenGIS standardization efforts. Another aim of the framework is that all GIS components can be easily integrated into network (internet) based information systems architectures. The framework is implemented in the programming language Java and uses many modern concepts like Java/Beans component technology and a middleware (Java/RMI) based multi tier architecture. Therefore the framework can be incorporated in different service architectures like middleware or WWW-Java/Applet service scenarios. The paper presents the architecture of the framework and shows how components of the framework are used in the network and service based system architecture of the EIS.