Consistency in software system development

Abstract

An important aspect in the software development process is the consistency between various parts of the software system being designed and implemented. During the development of a system we are aware of the consistency problems and we usually solve these by special arrangements developed as part of the development of the software system. In general the solutions applied for some specific system cannot be reused for other systems. The purpose of this paper is to introduce a general understanding of consistency and the techniques and tools for handling consistency. We introduce a concept called description to denote the various pieces of information which must be consistent. The description covers any fragments software and data, e.g. such as source code, parse trees, and machine code. The interpretation of a description is defined as a mapping into the set of objects, that the description is supposed to describe. Consistency of descriptions is defined as relations between the interpretations of the descriptions. The concepts description, interpretation and relation are used as a framework for modeling consistency in software systems. A consistency model includes interfaces, control parts and representions for descriptions in a system, and a specification of the consistency relations, that are relevant for the system. The model provides consistency as a new and very important perspective on software systems. It provides a graphical notation, which gives an overview of the consistency relations in a software system being designed. The model is very general and it does therefore apply to any type of software systems. This restricts the level of detail in the model of consistency, but the model allows enhancement of the specification once the type of software system is given. We define four basic techniques for handling consistency in software systems modeled in terms of descriptions. By combining these techniques we are able to describe the handling of consistency in a given software system. These techniques and the graphical consistency modeling language form a first step towards an engineered approach to the construction of software systems from a consistency view.