gms | German Medical Science

The cognitive exploration of a database as the foundation of an application system is becoming more and more difficult, since the complexity of the average database has increased tremendously due to the ever-extending technical limitations of such systems. In the Seventies of the last century, a database comprising 50 to 100 tables was considered complex --- nowadays, a full-fledged ERP system database will hold close to 30,000 tables with a matching number of inter-table relationships. The tools used to manage such intricate data structures have basically remained the same: mainly two-dimensional dynamic diagrams based on Peter Chen's [Ref. 2] notation depicting the database in different levels of detail.

It would be rather arrogant to assume that the cognitive capability of the human mind has remained in step with this ever-growing complexity. Therefore, news ways of visualization have to be investigated to support human administrators. One could argue that database design and administration simply has to follow the lead of other fields of expertise, e.g. precision engineering and medicine, where a three-dimensional approach to visualization induced a paradigmatic step towards management of extremely complex information.

The project outlined in this paper aims at a three-dimensional immersive visualization of databases, on different levels of detail and with various functional properties.

This approach has already been used in many instances (see e.g. [Ref. 3], [Ref. 4]). However, the emphasis is invariably directed at visualization of data to increase its transparency, not at understanding of the conceptual structures underneath, whereas the project described in this paper is mainly focused on the administrator's view of a database.

The universal standard for the propagation, export/import, and screening of virtual worlds is the Virtual Reality Modeling Language (VRML, see e.g. [Ref. 1]). This descriptive language can been seen as a 3-D visual extension of the World Wide Web. People can navigate through 3-D space and interact with objects that respond by pre-programmed animations or lead to other virtual world represented by URLs. VRML includes sensory components, interpolating animations, and a script language for flexible control.

The programming environment was chosen to be Java, mainly for its platform-independence and the standardized JDBC database interface for relational databases. In particular, JDBC provides extensive metadata information via Java method calls to obtain in-depth information on all available database structures and their properties and parameters.

VRML provides a class concept to support different representations for tables, relationships, and table contents. The three-dimensional layout may be modified by parameters to enable the user to deviate from the standard layout chosen by default. This layout would classify the tables according to the number of their relationships to other tables, use that classification to assign tables to layers, and arrange tables in a circular way.

The basic version of the system uses a stand-alone generator written in Java which retrieves all data and metadata information from the relational database and creates a VRML virtual world as ASCII output in a wrl file. This file, in turn, is interpreted by a standard viewer providing the user with fixed viewpoints for a walkthrough, but also with absolute navigational freedom to study the structures individually.

This prototype version of the system mainly serves as playground for "innocent" users to test how comfortable they feel navigating among tables and to see what insights they gain from the inner structures of their database.

Even in the current version, the generator has proven to be a tremendous support in the classroom teaching database classes due to its intuitive handling and the dynamic presentation of otherwise drab material. Students show considerable motivation to use the system themselves and seem eager to improve their navigational and interpretive skill.

Future generations will be at ease with three-dimensional virtual worlds as their workroom, just as the present generation is comfortable with the desktop metaphor. The results of the research presented in this paper are but a small step --- a step, however, in the right direction.