How should geographic information systems be developed? There is a strong demand from users for enhanced functionality and power. Vendors can and do respond to these demands. But where will this lead? Will the result be one all-embracing and all-conquering program or geographic information system (GIS)? A GIS could grow to incorporate all statistical functions, all visualisation techniques, all data management functions etc. It is possible to perceive a scenario in which GIS is developed to ‘bloatware’ proportions.
An alternative scenario is one in which a GIS is interfaced with other software systems. Embedding database bridges and other product-specific links, providing data import and export routines, and system calls are all ways of interfacing GIS with other systems. GIS vendors could opt to produce a ‘linkware’ GIS, interfaced to as many third party systems as possible.
Given these two alternatives to GIS development, an interesting set of questions arises. How far do vendors go with enhancing their systems compared with interfacing with third party systems? Is there a balance? Or do GIS users just keep calling for ‘more’, regardless of the solution set?
There is a balance. GIS is likely to be developed by being enhanced AND by being interfaced with third party software. In a way, this is a third developmental track leading to an increasingly functional GIS whose ability to interact with other systems is greatly improved. This interoperable GIS allows flexible combinations of systems components while still providing a comprehensive range of spatial operations and analytical functions.
Of these three developmental tracks, this paper presents an example of what can be achieved with the interoperable GIS. Expert systems are introduced along with the client/server and object-oriented paradigms. By using these paradigms, a generic, spatial, rule-based toolbox called SES (spatial expert shell) has been created. SES is described using examples and contrasted with other documented expert system-GIS linkages. But first integration is modelled in three dimensions to highlight the need for improvements in how GISs can interact with other systems.
