The growing need for computer software in different sectors of activity, (health, agriculture, industries, education, aeronautic, science and telecommunication) together with the increasing reliance of the society as a whole on information technology, is placing a heavy and fast growing demand on complex and high quality software systems. In this regard, the anticipation has been on non-functional requirements (NFRs) engineering and formal methods. Despite their common objective, these techniques have in most cases evolved separately. NFRs engineering proceeds firstly, by deriving measures to evaluate the quality of the constructed software (product-oriented approach), and secondarily by improving the engineering process (process-oriented approach). With the ability to combine the analysis of both functional and non-functional requirements, Goal-Oriented Requirements Engineering (GORE) approaches have become de facto leading requirements engineering methods. They propose through refinement/operationalisation, means to satisfy NFRs encoded in softgoals at an early phase of software development. On the other side, formal methods have kept, so far, their promise to eliminate errors in software artefacts to produce high quality software products and are therefore particularly solicited for safety and mission critical systems for which a single error may cause great loss including human life. This thesis introduces the concept of Complementary Non-functional action (CNF-action) to extend the analysis and development of NFRs beyond the traditional goals/softgoals analysis, based on refinement/operationalisation, and to propagate the influence of NFRs to other software construction phases. Mechanisms are also developed to integrate the formal technique Z/Object-Z into the standardised User Requirements Notation (URN) to formalise GRL models describing functional and non-functional requirements, to propagate CNF-actions of the formalised NFRs to UCMs maps, to facilitate URN construction process and the quality of URN models. / School of Computing / D. Phil (Computer Science)

Denna studie problematiserar icke-funktionella krav (IF krav), även benämnt kvalitetskrav, i svenska mjukvaruutvecklingsprojekt. Kravhantering anses vara den mest avgörande delen i mjukvaruutveckling för att lyckas, vilket än idag är en utmaning i majoriteten av projekten. Särskilt svårt är det att lyckas med IF krav, då tvetydigheter leder till brist på dokumentation och slutligen bortprioriteras de. För att adressera dessa problem syftade denna studie att besvara hur väl de IF kraven dokumenteras inom svenska mjukvaruutvecklingsprojekt samt vem som kan ansvara för att kvalitetssäkra de IF kraven. En mixed-method har genomförts med både en kvalitativ litteraturstudie av tidigare forskning samt en kvantitativ studie. Datainsamlingen i den kvantitativa studien har skett med webbaserad enkätundersökning med 24 frågor. Enkäten skickades ut till 72 företag i Sverige vars huvudsyssla var mjukvaruutveckling. Sammanlagt samlades 43 svar in och en univariat analys genomfördes. Enkätundersökningen indikerade att respondenterna är positivt inställda till dokumentation av IF krav. De flesta saknar dessutom gedigen kunskap om IF krav. Vidare saknas tydliga ansvarsroller för dokumentationen av IF krav. En lösnings- eller mjukvaruarkitekt är bäst lämpad för att kvalitetssäkra de IF kraven. Denna studie är skriven på svenska och kan främja studenter, forskare och yrkesverksamma då den nyanserar vikten av IF krav och hur existerande brister kan förbättras. / This study examines non-functional requirements (NFRs), also known as quality requirements, in Swedish software development projects. Requirements engineering is considered the most crucial part of software development, which is still a challenge in the majority of projects today. In particular, the NFRs are the most challenging seeing as there are ambiguities concerning their definition. This in turn leads to lack of documentation and, ultimately, their deprioritization. To address these issues, this study aimed to answer how well NFRs are documented in Swedish software development projects and who can be responsible for ensuring the quality of these NFRs. A mixed-method was conducted with both a qualitative literature review of previous research and a quantitative study. The data collection in the quantitative study was conducted using a web-based survey with 24 questions. The survey was sent to 72 software development companies in Sweden. A total of 43 responses were collected, and a univariate analysis was performed. The survey indicated that respondents have a positive attitude towards documenting. Additionally, most respondents lack comprehensive knowledge about NFRs and clear roles for the NFRs are missing. Standardization, better guidelines, and clear roles are needed to ensure the quality of NFRs, which are currently lacking. A solution or software architect is best suited to ensure the quality of NFRs. This study, written in Swedish, can benefit students, researchers, and professionals as it highlights the importance of NFRs and suggests improvements for existing deficiencies.