Background Digital technology is moving rapidly to distributed computing. It is now possible for parts of a database to be stored and maintained at different locations, for users to take advantage of economical or specialized processing at remote sites, for decision-makers to collaborate across computer networks to make decisions, and for large archives to offer access to their data to anyone connected to the Internet. New wireless technologies now allow communication virtually anywhere on Earth, and can potentially support a host of new types of mobile computing activity in the field. Modules may coexist in one system or may be distributed across a network and assembled only when needed and with minimal user intervention. Several common threads underlie these developments, and define distributed computing.
Wireless communication is particularly important for mobile computing.
Computing is ubiquitous if the user s ability to compute is independent of location. Computing is distributed if the data, software, and hardware needed for a project are distributed across several locations but appear to the user as if they were united. The problems and applications that GISs address seem particularly suited to take advantage of distributed computing. Geographic decisions supported by GISs must often be made by many stakeholder groups who are distributed both geographically and socially. In addition, stakeholders are often located in different tiers of an administrative hierarchy.