Exploring the UML Class Diagram

UML is the standard language for object-oriented software visualization, specification, construction, and documentation. Grady Booch, Ivar Jacobson, and Jim Rumbaugh at Rational Software Corporation developed UML, with contributions from other methodologists, software vendors, and users. UML is a combined methodology of the Booch, OMT, and Jacobson methods.

Note

You can find various documents at http://www.rational.com/uml/index.jsp. A good tutorial book on UML is The Unified Modeling Language User Guide (Addison-Wesley, 1998).

There are three kinds of building blocks in the UML vocabulary:

• Things

• Relationships

• Diagrams

You can group things in UML into four categories:

• Structural things

• Behavioral things

• Grouping things

• Annotational things

There are also four kinds of relationships in UML:

• Dependency

• Association

• Generalization

• Realization

The UML includes nine types of diagrams:

• Class diagram

• Object diagram

• Use case diagram

• Sequence diagram

• Collaboration diagram

• Statechart diagram

• Activity diagram

• Component diagram

• Deployment diagram

As you can see, UML addresses all the views needed to build and deploy object-oriented applications and therefore is very extensive. As such, tools for manipulating all aspects of the UML are also large applications. Understandably, such applications are not cheap. The most popular UML tools are the various products from Rational Software Corporation (http://www.rational.com). Alternatives include the Poseidon for UML Professional Edition and the Poseidon for UML Community Edition from Gentleware (http://www.gentleware.com). The latter is freely downloadable from the Web site.

Note

You can also use UML to model nonsoftware systems.

The project in this chapter addresses a tiny fraction of UML: the class diagram.