Information engineering for systems in Ada

Abstract

This paper describes a method for information engineering of Ada systems. It uses the "Principle of Locality" as a metric for structuring. The focus is on the information processed by the system. Information elements are related to Ada packages and procedures in an "Information Processing Matrix" (IP-matrix). A method for establishing the IP-matrix is described. Algorithms for transforming the IP-matrix to optimum diagonal form are also given. A metric for locality of information processing — called Dispersion Index — is defined.

The "IP-method" which is proposed in this paper is shown to give an overview over the system with respect to where and how information is processed. It also highlights structuring properties of the system with respect to how close around its level of abstraction the information in the system is processed. If the recommendations which this method presents are observed, it will be easier to manage implementation and maintenance of the system, since it will be simpler to control side-effects. The dispersion index presents a one-dimensional metric of the quality of system structuring in this aspect.

The concept of mapping information against processing in a tabular form has been presented before and is applied by some Information Engineering (IE) CASE products on the market. Application of IE methods to technical systems is however not commonly done. The definition of a "Dispersion Index" is specific to this paper. The method can be used for the early stages of design as well as for evaluating existing systems. It may be automated to parse and generate reports on existing software.