UML Diagrams

A diagram provides the user with the means of visualizing and manipulating model elements. The various types of UML diagrams are presented in the diagram below:

The different types of diagrams defined by UML

A UML diagram contains visual elements that represent model elements coming from different packages — even in the absence of visibility relationships between these packages. (Packages are discussed later in this chapter.)

The diagrams may show all or part of the characteristics of the model elements, with a level of detail that is suitable in the context of a given diagram. Diagrams may also gather together pieces of linked information to show, for example, the characteristics inherited by a class.

Here, in alphabetical order, is a list of the various diagrams:

• Activity diagrams represent the behavior of an operation as a set of actions
  
  
• Class diagrams represent the static structure in terms of classes and relationships
  
  
• Collaboration diagrams are a spatial representation of objects, links, and interactions
  
  
• Component diagrams represent the physical components of an application
  
  
• Deployment diagrams represent the deployment of components on particular pieces of hardware
  
  
• Object diagrams represent objects and their relationships and correspond to simplified collaboration diagrams that do not represent message broadcasts
  
  
• Sequence diagrams are a temporal representation of objects and their interactions.
  
  
• Statechart diagrams¹ represent the behavior of a class in terms of states
  
  
• Use case diagrams represent the functions of a system from the user's point of view

Sequence and collaboration diagrams can be grouped together under the more general title of interaction diagrams.