UML图中的可导航性是什么? [英] What is Navigability in UML diagrams?

问题描述

UML图中的可导航性示例是什么?我的教授提供了以下数据，但我似乎无法弄清楚:

What is an example of Navigability in UML diagrams? My professor has provided the follow figure, but I can't seem to figure it out:

推荐答案

这显示了可导航性. A 可以看到(意味着它具有属性引用) B .相反， B 不了解/未引用 A .

This shows navigability. A can see (means it has an attribute referencing) B. In contrast B has no idea about/reference to A.

UML 2.5 spec p.18:

UML 2.5 spec p. 18:

• 箭头符号用于表示关联端点的可导航性.根据定义，所有类拥有的关联端点都是可导航的.按照惯例，元模型中所有关联拥有的端点都是不可导航的.

• Arrow notation is used to denote association end navigability. By definition, all class-owned association ends are navigable. By convention, all association-owned ends in the metamodel are not navigable.

两端都没有用可导航性箭头标记的关联意味着该关联在两个方向上都是可导航的.

An association with neither end marked by navigability arrows means that the association is navigable in both directions.

甚至更相关.200:

过去，可导航性符号通常是根据非正式公约使用的，即不可导航的终端被假定为协会拥有，而可导航的终端被假定为分类器位于另一端.现在不推荐使用此约定.聚合类型，可导航性和最终所有权是独立的概念，每个概念都有其自己的显式表示法.类拥有的关联端点始终是可导航的，而协会拥有的关联端点则可能是不可导航的.

Navigability notation was often used in the past according to an informal convention, whereby non-navigable ends were assumed to be owned by the Association whereas navigable ends were assumed to be owned by the Classifier at the opposite end. This convention is now deprecated. Aggregation type, navigability, and end ownership are separate concepts, each with their own explicit notation. Association ends owned by classes are always navigable, while those owned by associations may be navigable or not.

因此，您应该改用点符号:

So you should use the dot notation instead:

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