面向对象的分析设计之RUP基础及用例建模.pptVIP

* * * * * 注意系统边界与参与者之间的关系 * * * * * * * * Three passes through the use cases typically result in the information required for the entire template. The first pass results in the use case survey. The second pass results in the use case draft. The third pass results in the generalized use cases. During development of the use case survey, the author provides the use case identifier, the author name and date information, the list of actors, and the use case description . During development of the use case draft, you will add the preconditions, the postconditions, the normal course of events, any alternative courses, and exceptions. A common mistake is to include two use cases in a single use case under the pretense of specifying an alternative course. We distinguish between the two use cases and one use case with an alternative course on the basis of what the user perceives. The purpose of the use case is to change the state of the system to a desired state, produce outputs, or a combination of the two. If an alternative course achieves a different purpose, you most likely have two use cases. Alternative courses are usually numbered with the first number indicating where the alternative course branches from the normal course. * * * * * * * * * * * 识别用例——用例要点 用例止于系统边界 用例是目标导向的 结果值由系统生成 业务语言而非技术语言，用户观点而非系统观点 用例的粒度 * 识别用例-用例的粒度 常见错误： 把交互的某个步骤当作用例 把系统活动当作用例 粒度过细，陷入功能分解 四轮马车的错误（增加、删除、修改、查询） * 用例分析流程 识别系统边界和参与者 列出事件 识别用例 编写用例规约（Use Case Specification） 识别用例的关系 对用例进行优先级排序 编写用例规约--用例的路径 * 编写用例规约-用例模板 用例编号 用例名 用例描述 参与者 前置条件 后置条件 基本路径（事件流） 1…..×××× ??2……×××× ??3…..×××× 扩展点 ??2a.×××× ?? 2a1….××××× 补充说明 编写用例规约--用例模板要素 Mandatory（必须） Element（要素） Phase（阶段） √ Author and date of the first version Gathering（需求收集阶段） Author and date of the latest revision Throughout（全过程） √ Actors Gathering √ Use case description 用例说明 Gathering √ Preconditions 前置条件 Specification（需求规格阶段） √ Postconditions 后置条件 Specification Priority Gathering √ Normal course of events 主流程 Specification Alternate cours