Formal specification based prototyping

Rapid prototyping is an approach to software development which attempts to remedy some of the shortcomings of the linear life cycle model, e.g. its inability to cope with fuzzy requirements and system evolution. This thesis first presents a broad survey of rapid software prototyping. It describes the rationale behind the process, the applications of prototyping, and specific techniques which may be used to achieve them. We then describe a system, called EPROS, together with its methodology, which supports a number of prototyping techniques in a coherent framework. The system is comprehensive in its approach and covers the prototyping and development of both functional and human-computer interface aspects of software systems. The former is based on the execution of VDM-based formal specification notation META-IV; the latter is based on a textual representation of state transition diagrams. Dialogue development is further supported by a rich set of abstractions which allow interaction concepts to be specified and directly executed rather than implemented. EPROS is based on a wide spectrum language which supports the main phases of a software development process, namely specification, design, and implementation. Included in this notation is a meta abstraction facility which facilitates its extension by the programmer. The primary application of EPROS is for evolutionary prototyping, where a system is developed iteratively and gradually from the abstract to the detailed, while it undergoes use and while its capabilities evolve. EPROS copes with all the requirements of evolutionary prototyping, namely rapid development, intermediate deliveries and gradual evolution of the system towards the final product. The thesis also describes a number of case studies where the presented ideas are put in practice, and which provide data in support of the effectiveness of the described system

Evaluating technology for elders : towards a measure of attitudes

Technology is ubiquitous in modern day society and has the potential to enhance one's quality of life. Numerous innovative assistive technologies are designed to aid elderly people in every day activities and enable them to maintain a measure of independence longer. One such assistive technology was the PAM-AID walking aid: a robotic walking aid designed to provide frail, visually impaired elders with the physical support of a rollator, coupled with the navigational assistance necessary for safe, independent mobility. A user-centred design approach was integral to the design and development of PAM-AID and the first part of this thesis, details the research undertaken to ensure that, as far as possible, PAM-AID met the needs of potential users. Studies were conducted with carers and elders to establish elders' requirements for PAM-AID. The results of these studies directly influenced the functional specification of the first PAM-AID prototype. Following an iterative design life cycle, further studies were conducted to evaluate the usability of the first and second prototypes and the results of these studies enabled informed design decisions could be made. Therefore, elders were involved at every stage of the design process, to ensure that PAM-AID was an efficient and acceptable technology to this user group. However, throughout this preliminary work, an interesting discrepancy in elders' attitudes began to emerge. It became evident that although elders thought that PAM-AID was a useful walking aid for other frail elderly people, they did not think that PAM-AID was beneficial for them personally. In other words, elders' attitudes indicated that they might not use or accept PAM-AID, even though they would clearly benefit from this innovative technology. Indeed, other research has shown that many assistive technologies are often under utilised or discarded by elders, even when the potential benefits of the technology are clearly evident. This was a pivotal point in the research programme, as it highlighted the importance of monitoring elders' attitudes to predict future use of and acceptance of assistive technology. Since no applicable tool exists for measuring individuals' attitudes to technologies such as PAM-AID, the main empirical work of this research programme involved the development of a psychometric scale: the Attitudes to Technology Scale (ATS). The inductive approach to development of this scale involved: the generation of items, the reduction of the items into meaningful subscales, as well as the demonstration of the scale's reliability and validity. Throughout its development, the scale was applied to a number of different types of technology such as ATMs, computers, microwaves, mobile phones, VCRs and the Internet. The scale has been used to investigate the effect of age and sex differences in terms of attitudes to technology. Thus, the ATS is unique in that it has been developed for use with ID1 types of technology and with individuals of ~ ages. The limitations of the scale have been noted and further work is needed to address these limitations. It is hoped that this scale will have both academic and commercial research applications, but above all, the ATS could be applied to continually monitor users' attitudes during the design and development of new technologies. It is proposed that the measurement of users' attitudes should be an integral part of the design life cycle, resulting in more useable and acceptable technology

Estimating the effort in the early stages of software development.

Estimates of the costs involved in the development of a software product and the likely risk are two of the main components associated with the evaluation of software projects and their approval for development. They are essential before the development starts, since the investment early in software development determines the overall cost of the system. When making these estimates, however, the unknown obscures the known and high uncertainty is embedded in the process. This is the essence of the estimator's dilemma and the concerns of this thesis. This thesis offers an Effort Estimation Model (EEM), a support system to assist the process of project evaluation early in the development, when the project is about to start. The estimates are based on preliminary data and on the judgement of the estimators. They are developed for the early stages of software building in which the requirements are defined and the gross design of the software product is specified. From these estimates only coarse estimates of the total development effort are feasible. These coarse estimates are updated when uncertainty is reduced. The basic element common to all frameworks for software building is the activity. Thus the EEM uses a knowledge-base which includes decomposition of the software development process into the activity level. Components which contribute to the effort associated with the activities implemented early in the development process are identified. They are the size metrics used by the EEM. The data incorporated in the knowledge-base for each activity, and the rules for the assessment of the complexity and risk perceived in the development, allow the estimation process to take place. They form the infrastructure for a 'process model' for effort estimating. The process of estimating the effort and of developing the software are linked. Assumptions taken throughout the process are recorded and assist in understanding deviations between estimates and actual effort and enable the incorporation of a feedback mechanism into the process of software development. These estimates support the decision process associated with the overall management of software development, they facilitate management involvement and are thus considered as critical success factors for the management of software projects