UML三个关键因素之规则

Rules of the UML

The UML’s building blocks can’t simply be thrown together in a random fashion. Like any language, the UML has a number of rules that specify what a will-formed model should look like. A well-formed model is one that is semantically self-consistent and in harmony with all its related models.

 

The UML has syntactic and semantic rules for

Names        What you can call things, relationships, and diagrams.

Scope          The context that gives specific meaning to a name

Visibility     How those names can be seen and used by others

Integrity      How things properly and consistently relate to one another

Execution   What it means to run or simulate a dynamic model

 

Models build during the development of a software-intensive system tend to evolve and may be viewed by many stakeholders in different ways and at different times. For this reason, it is common for the development team to not only build models that are well-formed, but also to build models that are

Elided                 Certain elements are hidden to simplify the view

Incomplete          Certain elements may be missing

Inconsistent        The integrity of the model is not guaranteed

 

These less-than-well-formed models are unavoidable as the details of a system unfold and churn during the software development life cycle. The rules of the UML encourage you -- but do not force you -- to address the most important analysis, design, and implementation questions that push such models to become well-formed over time.

 

UML中的基本模块并不是随意的丢到一起就构成一个模型．就想任何语言一样，UML同样有许多规则用来描述良好结构的模型是什么样子．一个具有良好结构的模型在语义上独立及与其它关联的模型保持一致．

 

应用UML的语法和语义规则的有：

名称          元件，关联和图的名字

范围          描述名称含义的文本

可视性     这些名称被其它人或物看到或使用的程度

整合性     事件与其它元件关联的正确性和完整性

执行性     运行和模拟动态模型的方式

 

在为一个复杂的软件建构模型时，多个权益人总是以不同的方式和在不同的时间影响着软件的进化．因此，开发团队不仅在建构良好结构的模型，而且在构建模型时容易出现：

省略     　     某些元素被隐藏以简化视图

不完整          某些元素可能被丢失

不一致          没有保证模型的完整性

 

在软件开发生命周期中，展开和制作系统的细节时出现比良好结构稍差一点的模型是不可避免的．UML的规则鼓励你，但不强制你处理更重要的分析，设计和实施问题，将这类的模型慢慢的发展成良好结构的模型．