The role of quality requirements in software architecture design

An important issue during architectural design in that besides functional requirements software architecture is influenced greatly by quality requirements which often are neglected. The earlier quality requirements are considered the less effort is needed later in the software lifecycle to ensure a sufficient software quality level. Errors due to lack of their fulfillment are the most expensive and difficult to correct. Therefore attention to quality requirements is crucial during the process of architectural design. The problem is only to gather these requirements but also to establish a methodology that helps to deal with them during software development. To alleviate the problem this paper lays out important concepts and notions of quality requirements in a way they can be used to drive design decisions and evaluate architecture to estimate whether these requirements are fulfilled.