Formal object oriented requirements: simulation, validation and verification

Requirements engineering is the first step in the software engineering process. A major part of building requirements is the modelling of the system to be developed (or updated) together with the system environment. These models are, of course, abstractions of the real world and as such we can say that they are simulations which need to be validated to show that they actually correspond to what exists or what is required. They also have to be verified to show their consistency. Requirements models have 3 distinct roles — they are the principle media of communication between clients and requirements engineers, they are the only model upon which rigorous and automated analysis can be carried out before development begins, and they are the structural foundation upon which design and implementation depend. We advocate a formal object oriented approach which can be presented in a client-friendly manner, using graphical representations. The overall theme of this paper is the triangle of integration in our simulations — we integrate user-friendly (graphical) animation of operational requirements during validation, together with proof of logical properties during verification, together with the structural object oriented concepts which support formal incremental development techniques.