软件体系结构ATAM.pptVIP

? sun@hit.edu.cn 软件体系结构ATAM 孙志岗 sun@hit.edu.cn Architecture Tradeoff Analysis Methodsm(ATAMsm) SMATAM and Architecture Tradeoff Analysis Method are registered service marks of Carnegie Mellon University Role of a Software Architecture If the only criterion for software was to get the right answer, we would not need architectures.如果评判软件的唯一标准是正确，那么就不需要体系结构 Unstructured, monolithic systems would suffice.无结构的、单模块的系统已经足够。 But other things also matter, such as:但事实上还有很多其他问题，比如： modifiability time of development performance coordination of work teams These issues are often addressed in the Software Architecture这些问题通常体现在软件体系结构当中 Why Analyze Software Architectures? All design involves tradeoff in system qualities（设计即折中） System qualities are largely dependent on architectural decisions体系结构极大地影响系统质量 Promoting one quality often comes at the expense of another quality提高一个质量，经常会降低另一个质量 A software architecture is the earliest life-cycle artifact that embodies significant design decisions: choices and tradeoffs.“选择与折中”是设计中首要考虑的问题，软件体系结构是软件生命周期中最早一个遇到此问题的 Choices are easy to make, but hard to change once the system is implemented选择很容易做，但是一旦系统已经实现，就很难更改 The ATAM The purpose of the ATAM: is to assess the consequences of architectural decisions in light of quality attribute requirements.ATAM的目标是：按照质量需求，评价体系结构设计 Context for the ATAM Purpose of ATAM We need a method in which the right questions are asked early to我们需要一个新方法，让我们能尽早提出正确问题，来： Discover risks - alternatives that might create future problems in some quality attribute发现风险：可能在将来产生质量问题的方案 Discover non-risks - decisions that promote qualities that help realize business/mission goals发现非风险：可以提高质量的决策 Discover sensitivity points - alternatives for which a slight change makes a significant difference in some quality attribute发现关键点：方案中一个小小的变化，就可能让质量完全大变样 Discover tradeoffs - decisions affecting more than one quality attribute发现折中：影响一个以上质量的决策 Purpose of ATAM The purpose of an ATAM is NOT to provide precise analyses, but to