Software Construction: UML Part 1

Class diagrams show generic descriptions of possible systems. It represents a static view of a software system.

Attributes & Operations are also called features

Danger: class diagrams risk turning into data models. Be sure to focus on behavior

Attributes are "variables" that hold specific values.

Operations are "functions" that (can) operate on the arrtibutes.

+ for public

- for private

# for protected

italic for abstract

... signals further entries are not shown

underlined attributes have class scope (?)

In the header: <<Stereotype>> (i.e. interface, utility,...) & {User-defined properties} (i.e. abstract)

Constraints are restrictions on values attached to classes or
associations. A constraint is depicted by a dotted line and usually annotated.

An association is a structural relationship that represents objects can be connected or associated with another object inside the system (e.g. usage).

Usually binary (but may be ternary, etc.)

Optional name and direction

(unique) role names and multiplicities at end points

It is denoted by a solid line.

A dependency describes the dependent elements & the direction of dependency.

Dependency is represented by a dotted arrow. The arrow head represents the independent element and the other end represents the dependent element.

As the name suggests, the directed / navigable association is related to the direction of flow within association classes. The association from one class to another class flows in a single direction only.

It is denoted using a solid line with an arrowhead.

Within a realization relationship, one element describes some responsibility, which is not implemented and the other one implements them. This relationship exists in case of interfaces. It is represented by a dotted arrow with a hollow arrow head pointing to the responsibility (e.g. an interface).