Class

1. A class diagram is a presentation of entities (people, things, thoughts) and relations between entities. • Class • A class is a collection -abstract definition- of attributes and functions. A class has a name. It can have a stereotype. • An object is a realisation of a class. • Attribute • An attribute is a variable with a value in a domain. A type is a primitive like integer, string etc. • A class can have attributes. • An attribute can be visible for other objects. • Function • A function (also method, operation, service) is an operation on attributes, functions and classes. A functiones defines the behaviour of the class. • A well-defined function does only one thing. • A function can be visible for other classes. • Association • An association defines the relation between classes and how they are related. Properties of relations are, a.o, name and multiplicity. • Visibility • The visibility defines for which classes attributes and operatons are visible. • Multiplicity • The multiplicity defines the amount of objects of a class.

2. An association defines the relation between classes.

3. Example of a class diagram

4. A sequence diagram shows classes with events in a specific order • Lifeline • The order in which events take place with a participant. A participant is a class, component or actor. • Actor • An actor is a system or person outside the system. • Message • Information from one class to an other. • Activation bar • The activation bar –also focus of control- defines the time a class is busy with processing the message. • Frame • A frame contains a part of a diagram or other diagram. • The part of a diagram can have specific meaning like: option, loop, alternative.