Commentary

Association and aggregation refer to structural relationships between objects. In normal aggregation parts may be added or removed; parts may survive after the whole has died. In containment aggregation the parts are contained in the whole and die with the container. Dependency refers to relationships between whole classes; type of parameter passed to the calling class or the type of returned value. Generalisation is finding the superclass from subclasses, specialisation is the opposite. Realization is implementing classes that collaborate to realize the use case. Interfaces are realised by the classes or components that implement them.