Quality Goal Oriented Architectural Design and Traceability for Evolvable Software Systems

Today software systems are frequently faced with demands for changes, for example, due to changing business processes or technologies. The software and especially its architecture has to cope with those frequent changes to permanently remain usable. During software evolution changes can lead to a deterioration of the structure of software architectures called architectural erosion, which hampers or even inhibits further changes because of inconsistencies or lacking program comprehension. To support changes and avoid erosion, especially quality goals, such as evolvability, performance, or usability, and the traceability of design decisions have to be considered during architectural design. This however often is neglected. Existing design methods do not sufficiently support the transition from the quality goals to appropriate architectural solutions because there is still a gap between requirements engineering and architectural design methods. Particularly support is lacking for the goal evolvability and for the traceability of design decisions by explicit model dependencies. This thesis presents a new concept called Goal Solution Scheme, which provides a mapping from goals via architectural principles to solution instruments by explicit dependencies. Thus it helps to select appropriate architectural solutions according to their influence on quality goals. The scheme is discussed especially regarding evolvability, and it is embedded in a goal-oriented architectural design method, which enhances and integrates established methods and concepts from requirements engineering as well as architectural design. This is supplemented by a traceability concept, which combines a rule-based approach with information retrieval techniques for a (semi-) automated establishment of links with specific link types and attributes for rich semantics and a high precision and recall. The feasibility of the design approach has been evaluated in a case study of a software platform for mobile robots. A prototype tool suite called EMFTrace was implemented as an extensible platform based on Eclipse technology to show the practicability of the thesis’ concept. It integrates design models from external CASE tools in a joint model repository by means of XML technology, applies rules for link establishment, and provides validation capabilities for rules and links.