Managing non-functional requirements in agile software development

Non-functional requirements define qualities of the software system that ensure effectiveness while embedding any constraints and restrictions on the design. A challenge rises with agile implementation in handling non-function requirements in regulated environments. Thus, a practitioner's perceptions of agile method tailoring are described in relation to inter-team boundaries and non-functional requirements. The research comprises 18 practitioner interviews from two multinational agile software development companies. Interviews were recorded, transcribed, and analysed using an approach informed by grounded theory and information flow models were used to compare and contrast interactions of processes. It was discovered that one of the case study companies managed non-functional requirements as artefacts in their agile methodology, while the other company reverts to conventional plan-based software development practices of documentation, timeline estimations, and safety critical requirements. This research creates a detailed comparison of these contrasting approaches. The main contribution of this study is a set of proposed recommendations to deal with non-functional requirements in a regulated environment using agile techniques. The introduction of two new artefacts, Documentation Work Item and Safety Critical Work Item, is recommended and it is accompanied with an illustrative example, to transform the handling of documentation and safety critical requirements in a more agile way.