Requirements engineering aspects for sustainable eLearning systems

Sustainability in software engineering is about (1) continued functionality and maintainability in changing circumstances, and (2) functionality's effect on the surrounded environment, economic and people. Frequent changes of software requirements negatively affect sustainability of software systems. To reduce the number of requirements' changes and improve sustainability, sustainability requirements have to be considered from the beginning of the requirements engineering stage of software development. Sustainability in requirements engineering has five dimensions including individual, social, technical, economic and environmental dimensions. Most of the existing work analysed only one or two dimensions and ignore the interrelated effects among other dimensions. To address this issue, we selected eLearning systems because they provide comprehensive example to study. This thesis focuses on analysing sustainability requirements of eLearning systems with regard to the five sustainability dimensions. The following studies were performed: (1) identifying theoretically the sustainability requirements of eLearning systems, (2) investigating empirically the sustainability of eLearning systems, (3) constructing a methodology for the analysis and evaluation of sustainability requirements on eLearning systems, and (4) evaluating the constructed methodology. To the best of our knowledge, this is the first research conducted to investigate sustainability requirements of eLearning systems covering the five sustainability dimensions. Our findings highlighted that (1) technical, economic and environmental sustainability requirements are similar to other software domains, where individual and social sustainability requirements are specific for the domain of eLearning systems, (2) individual and social sustainability requirements need to be carefully considered and analysed together because of the strong correlation, and (3) culture and gender diversity play an important role for sustainability requirements. On this basis, we developed a framework for analysing sustainability requirements of software systems as well as a web-based tool SuSoftPro (the name stands from Software Sustainability Profiling) that allows requirements engineers to: investigate sustainability of software systems based on the systems' requirements, analyse the sustainability dimensions of software systems, measure the sustainability of each individual requirement, visualise analysis results to support decision making towards high-quality software, involve stakeholders to rate their requirements for one or more of the five sustainability dimensions, and manage requirement and stakeholder details easily. We evaluated the SuSoftPro framework through case studies, comparative evaluation and a quantitative questionnaire. Our framework successfully provides a comprehensive view of analysing sustainability requirements to improve the attention to sustainability and allow practitioners to develop sustainable software