Chapter 5. Architectural Design

Chapter 5. Architectural Design Architect "Every system has an architecture, encompassing the key abstractions and mechanisms that define that system's structure and behavior as seen from the perspective of different stakeholders, each with a different set of concerns. In every casefrom idioms to mechanisms to architecturesthese patterns are either intentional or accidental, but insofar as they are visible, such patterns reflect the style and inner beauty of each system."[1] Grady Booch, Handbook of Software Architecture Figure 5.1. Every system has an architecture. The honeycomb of a beehive is a great example of an architecture whose conceptual integrity allows and applies patterns, continual evolution, flexibility, scaling, and reuse. Architectural design transforms the requirements, as captured in scenarios and qualities of service into designs that can be built to satisfy and delight users. The analogy between the work of software architects and civil architects has been made countless times to illustrate the point. Civil architecture, however, consists not only of the work of professional architects but also of thousands of years of craftsmanship in the application of patterns that work.[2] A good architecture reflects a conceptual integrity that makes the architecture easy to understand, use, maintain, and evolve. This conceptual integrity is typically achieved through the choice, application, and specialization of the right patterns to the broad qualities of service and scenarios defined for a system. Although there is broad agreement on the characteristics of a good architecture, there is controversy about the process of architectural design. The extremes range from the concept that architectural design should be practiced independently of implementation[3] to the idea that architecture should emerge from implementation.[4] Accordingly, architecture is sometimes an explicit process, whereas at other times it is a set of activities combined closely with development.