CHAPTER 3 - UML—Unified Modeling Language

Abstract

UML had originally been developed to create models for software systems. The word unified stands for the claim that the language can be used for software systems of a large number of different domains—from business and economics systems to the development of standard software products to technical systems, such as an airbag control. UML is extensible to ensure that it is unified and, on the other hand, can offer useful model elements for specific domains and disciplines. Stereotypes and profiles offer a controlled extension mechanism that allows projects to define new modeling elements. Many software projects have been used UML to generate simple source-code scaffolding. Several integrated development environments support this approach by using UML as a graphical editor for the source code. The structure of a class is defined by the sum of its attributes. Here the abstraction of the model compared to the real world plays an important role. The attributes reflect only the structure that is relevant for the model. UML defines four different visibility types: public (denoted as +)—the attribute is publicly visible. Each element outside the class can access this attribute; private (denoted as –)—the attribute is private. No element outside the class can see this attribute; package (denoted as ∼)—the attribute is visible to all elements located in the same package as the class; protected (denoted as #)—the attribute is visible only to subclasses of the pertaining class. A composite structure diagram describes the internal structure of classes on role level.