Preserving the time dimension in information systems (database, graphics)

Time is a universal and pervasive aspect of human activities, yet it is rarely reflected in the ways computer-based information systems are constructed. This dissertation thus focuses on the identification of a useful and feasible design of a data management system that captures and preserves the inherent dynamics of its content, and explicitly deals with time as it stores, retrieves, and presents data. The major results of this study are the identification of functional requirements for temporally oriented information systems, the formulation of a data model that captures subtle aspects of the time dimension, the formulation of end-user's syntax for querying a database based on such data model, and the design of an integrated user interface that graphically conveys temporal properties of data retrieved from the associated database. The initial part of the dissertation explicates the guidelines along which the temporally oriented data model and a corresponding data management system were developed. These quidelines are based on a comprehensive survey of time notions in conceptual data models, human perception of time, structures of memory and managerial planning and control, and informational propagation delays. The resulting data model introduces the cube, a data construct which operationalizes the pervasive spatial metaphor for time: time augments the traditional dimensions (i.e., objects and attributes) of the relational data construct. The cube provides the framework for storage and basic manipulations of data within its temporal context. This data model underlies the Temporally Oriented Data Management System (TODMS), which integrates a historical DBMS with a compatible user interface. The implementation design of the DBMS includes the specification of a temporally enhanced SQL query syntax, and a graphic interface that automatically generates animated pictorial representations for the queries' output. This integrated design provides a tangible means for experiencing the temporal dimension of data: users can thus retrieve a data cube from the database and then spatially browse through it.