Applying visualisation to model-based formal specifications.

The most important and challenging activity in developing new software systems is arguably ascertaining their features and characteristics before development takes place. This activity, known as requirements engineering, involves software developers identifying the requirements of the customers who are procuring the system, and then documenting them in a requirements specification.Producing a requirements specification is a complex, time consuming and human-centred activity. It is essential that both parties discuss the requirements, analyse them and negotiate any issues, uncertainties or conflicts that arise. To assist in this process, a prototype of the software can be developed and then thrown away after the requirements process has been completed. Such a prototype helps to stimulate discussion and to provide a vehicle for experimentation and evaluation. This form of prototyping is now a popular and well-known requirements engineering technique. One powerful throwaway prototyping approach involves developing prototypes quickly using executable model-based formal specifications. These are based upon mathematical notations that possess a defined syntax and semantics. They have a useful dual role in the requirements process. On the one hand, they can be used to express requirements specifications in a precise and unambiguous manner, whilst on the other they can also be subjected to execution to produce a prototype. However, despite the benefits that such executable specifications have for the developer, their use can be problematic in situations that involve communication with customers. This is because traditionally, for reasons of productivity, the execution behaviour of prototypes developed in this manner is often depicted using developer-centred representations. Such representations often do not correspond to the perceptions or expertise of the customer, as they are often too abstract or technical. If the customer cannot recognise or comprehend these, accurate evaluation of the prototype cannot take place, stifling much needed dialogue and rendering the prototyping process ineffective.This research advocates that applying visualisation to this form of prototyping can alleviate the problems of comprehension and the subsequent breakdown in dialogue. The objective is to employ the techniques and principles of visualisation to transform the developer-centred prototype execution behaviour into customer-oriented representations based upon pictorial and graphical forms from their own universe of discourse. Applying visualisation in this way can retain the advantages of using executable formal specifications to build prototypes, while at the same time stimulating and sustaining effective dialogue between developers and customers. The objective of the research concerns the production of a system for visualising the execution of a specific executable formal specification-based prototype development technique. The resulting system is then evaluated by demonstrating its application in a series of case studies. These reveal the capabilities of the approach, and demonstrate the benefits that can be gained over and above the use of existing prototyping techniques based on executable formal specifications.