Towards quantifying quality, tactics and architectural patterns interactions

Architectural design involves choosing the best design solution that satisfies a set of requirements. During this process the architect has to assess and compare multiple, and possibly conflicting, criteria and decisions including quality attributes, architectural tactics and patterns. While architectural patterns embody high level design decisions, an architectural tactic is a design strategy that addresses a particular quality attribute. Tactics, in fact, serve as the meeting point between the quality attributes and the software architecture. To guide the architect in selecting the most appropriate architectural patterns and tactics, the interactions between quality attributes, tactics and patterns should be analyzed and quantified and the results should be considered as decision criteria within a quality-driven architectural design process. In this paper, we propose an approach for a quantitative evaluation of the support provided by a pattern for a given targeted set of quality attributes. Our approach incorporates the mathematical based trade-off technique: Analytical Hierarchy Process (AHP) to quantitatively deal with ambiguities, trade-offs, priorities and interdependencies among qualities, tactics and architectural patterns.