Software Design Engineering

Design engineering commences as the first iteration of requirements in software engineering. The intent of software design is to apply a set of principles, concepts, and practices that lead to the development of a high-quality system or product. The goal of design is to create a model of software that will implement all customer requirements correctly and bring delight to those who use it. Design engineers must sift through many design alternatives and converge on a solution that best suits the needs ofproject stakeholders.

The design process moves from a “big picture” view of software to a more narrow view that defines the detail required to implement a system. The process begins by focusing on architecture. Subsystems are defined; communication mechanisms among subsystems are established; components are identified; and a detailed description of each component is developed. In addition, external, internal, and user interfaces are designed.

Design concepts have evolved over the first half-century of software engineering work. They describe attributes of computer software that should be present regardless of the software engineering process that is chosen, the design methods that are applied, or the programming languages that are used.

The design model encompasses four different elements. As each of these elements is developed, a more complete view of the design evolves. The architectural element uses information derived from the application domain, the analysis model, and available catalogs for patterns and styles to derive a complete structural representation of the software, its subsystems and components. Interlace design elements model external and intemal interfaces and the user interface. Component-level elements define each of the modules; (components); that populate the architecture. Finally, deployment-level design elements allocate the architecture, its components, and the interfaces to the physical configuration that will house the software.

Pattern-based design is a technique that reuses design elements that have proven successful in the past. Each architectural pattern, design pattern, or idiom is cataloged, thoroughly documented, and carefully considered as it is assessed for inclusion in a specific application. Frameworks, an extension of patterns, provide an architectural skeleton for the design of complete subsystems within a specific application domain.