06/01/1990 09:00 AM
Computer Science
A distributed heterogeneous environment is created when a variety of different computer systems are connected and interacting with each other over a network. In such a situation, it is often desirable to make the same program work in environments using different I/O devices, window systems, and processors. The purpose of this thesis was to make it easy for application developers to write programs compatible with different environments. An interactive application program has two components, its functionality(sometimes called computational component) and its user interface. The only component that changes in a different environment is the user interface. The functionality of a program remains the same. If the user interface is intertwined with the functionality, the whole program will need to be rewritten when the program is moved to a new environment. If the functionality and the user interface are developed independently, only the user interface will need to be changed in a different environment. In this thesis the design of an User Interface Abstraction Model is presented. The model facilitates dialogue independence between the functionality and the user interface by providing an interface abstraction. Dialogue independence means that the design decisions affecting the computational component can be changed independent of the user interface. The interface abstraction creates a buffer between the two components using abstract data types. The data types support choices from a list for tables and selections. The design of the User Interface Abstraction Model is validated by the implementation of an `Image Browser\' application in two different environments: the X Window System and a character-based terminal environment. Only the user interface required changes in a different environment; the computational component remained unaltered. Notes: M.S. Thesis

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