In a binary association both ends may attach to the same class The links of

In a binary association both ends may attach to the

This preview shows page 55 - 59 out of 165 pages.

In a binary association both ends may attach to the same class. The links of such an association may connect to two different objects from the same class or one object to itself. The latter case is a Recursive or reflexive association; it may be forbidden by a constraint if necessary Example for reflexive association Product Sale
Image of page 55
Association End An association Role is simply an end of an association where it connects to a class It is part of the association, not part of the class Each association has two or more ends The path may have graphical adornments at each end where the path connects to the class symbol These adornments indicate properties of the association related to the class An association end is simply an end of an association where it connects to a class. It is part of the association, not part of the class. Each association has two or more ends. Most of the interesting details about an association are attached to its ends. An association end is not a separable element; it is just a mechanical part of an association. The path may have graphical adornments at each end where the path connects to the class symbol. These adornments indicate properties of the association related to the class. The adornments are part of the association symbol, not part of the class symbol. The end adornments are attached to the end of the line. car person Driver Company car * * drives * *
Image of page 56
N-Ary Association An association among 3 or more classes (a single class may appear more than once) Each instance of the association is an n-tuple of values from the respective classes Multiplicity may be indicated An n-ary association is shown as a large diamond with a path from the diamond to each participant class The name of the association (if any) is shown near the diamond An n-ary association is an association among 3 or more classes (a single class may appear more than once). Each instance of the association is an n-tuple of values from the respective classes. A binary association is a special case with its own notation. Multiplicity for n-ary associations may be specified but is less obvious than binary multiplicity. The multiplicity on a role represents the potential number of instance tuples in the association when the other N-1 values are fixed. An n-ary association may not contain the aggregation marker on any role. Generalization Is a relationship between a more general element and a more specific element Generalization is shown as a solid-line path from the more specific element (such as a subclass) to the more general element (such as a superclass), with a large hollow triangle at the end of the path where it meets the more general element Generalization may be applied to associations as well as classes Generalization is the taxonomic relationship between a more general element and a more specific element that is fully consistent with the first element and that adds additional information.
Image of page 57
Dependency
Image of page 58
Image of page 59

You've reached the end of your free preview.

Want to read all 165 pages?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture