Modifiability Tactics

An architectural tactic is a design decision that affects how well a software architecture addresses a particular quality attribute. This report describes how tactics are based on the parameters of quality attribute models. Tactics provide an architectural means of adjusting those parameters, which, in turn, can improve the quality-attribute-specific behavior of the resulting system. This report justifies the tactics for modifiability, using established concepts of coupling, cohesion, and cost motivations as the means of identifying parameters of interest. Various tactics are then described based on their ability to control these parameters. The report also describes a standard set of architectural patterns and their variants in terms of the use of these tactics.