《面向对象分析与设计》读书摘要与学习笔记（一）

有关软件开发的中的“复杂性”问题

Why complexity is an essential property of all software system??

主要有4个因素

a. the complexity of the problem domain

b. the difficulty of managing the development process

c. the flexibility possible through software

d. the problems of characterizing the behavior of discrete system

复杂系统的基本结构

No centralized parts that directly coordinate the activities of lower level ones. Instead of parts that act as independant agents, each of which exhibits some fairly complex behavior, and each of which contributes to mang higherlevel functions.

复杂系统的5要素

a. Frequently, complexity takes the form of hierarchy, whereby a complex system is composed of interrelated subsystems

that have in turn their own subsystems, and soon, until some lowest level of elementary components is reached.

b. The choice of what components in a system are primitive is relatively arbitrary and largely up to the discretion of

the observer of the system.

c. Intracomponent linkages are generally stronger than intercomponent linkages. This fact has the effect of separating

the high-frequency dynamics of the components-involving the internal structure of the components-from the low frequency

dynamics-involving interaction among components.

d. Hierarchic system are usually composed of only a few different kinds of subsystems in various combinations and arra-

ngements.

e. A complex system that works in invariouly found to have evolved from a simple system that works. A complex system d-

esigned from scratch never works and can\'t be patched up to make it work. You have to start over, beginning with a wor-

king simple system

------- to be continued~~