个人软件过程 L7 Software Design I.pptVIP

Lecture Topics The design framework Design completeness Design representation The PSP design templates operational specification functional specification state specification logic specification The design hierarchy Design is a Learning Process Design involves discovery, invention, and intuitive leaps from one abstraction level to another. While the design must reflect the requirements, requirements usually are not stable until the product has been used, if then. Design work is iterative, and it must be driven by feedback from all involved parties. The critical problem is knowing when to freeze the design to produce the next iteration. The Design Framework Development Framework Design Quality Design is a defect prevention activity. Poor quality designs are a major source of rework, maintenance, and user dissatisfaction. A quality design is complete and precise meets the user’s needs precisely guides implementation Design Levels Design work is an inverted pyramid in which each level provides a foundation for the following levels debugs the preceding levels To save time and prevent defects, document all design decisions at all levels when they are made. Structuring the Design Process Good software designers follow a dynamic process. They jump from concept to detail simultaneously consider issues at several design levels explore multiple alternatives A structured design process can help you to manage the dynamics of design. capture what has been learned record and manage issues track design status A properly-implemented design process will reduce rework, manage routine tasks, and give the designer the freedom to be creative. The Design Hierarchy The PSP Design Process Since there is no single best design method, the PSP supports multiple methods. The PSP focuses on what a complete design should contain. The goal is to eliminate requirements and design defects. The PSP uses design templates to provide criteria for design completeness reviewable designs