An association can be named, and the ends of an association can be adorned with role names, ownership indicators, multiplicity, visibility, and other properties. An association with three links is called a ternary association. An association can link any number of classes. A binary association (with two ends) is normally represented as a line. AssociationĪn association represents a family of links. A dependency is displayed as a dashed line with an open arrow that points from the client to the supplier. It exists between two elements if changes to the definition of one element (the server or target) may cause changes to the other (the client or source). UML defines the following relationships: Instance-level relationships DependencyĪ dependency is a type of association where there is a semantic connection between dependent and independent model elements. RelationshipsĪ relationship is a general term covering the specific types of logical connections found on class and object diagrams. In order to further describe the behavior of systems, these class diagrams can be complemented by a state diagram or UML state machine. In detailed modeling, the classes of the conceptual design are often split into subclasses. In the design of a system, a number of classes are identified and grouped together in a class diagram that helps to determine the static relations between them. They are also left-aligned and the first letter is lowercase. The bottom compartment contains the operations the class can execute.They are left-aligned and the first letter is lowercase.

The middle compartment contains the attributes of the class.It is printed in bold and centered, and the first letter is capitalized. The top compartment contains the name of the class.In the diagram, classes are represented with boxes that contain three compartments: Class diagrams can also be used for data modeling. The classes in a class diagram represent both the main elements, interactions in the application, and the classes to be programmed. It is used for general conceptual modeling of the structure of the application, and for detailed modeling, translating the models into programming code. The class diagram is the main building block of object-oriented modeling. In software engineering, a class diagram in the Unified Modeling Language (UML) is a type of static structure diagram that describes the structure of a system by showing the system’s classes, their attributes, operations (or methods), and the relationships among objects.

Email system class diagram