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Commentary

Class diagrams give the static structure of the system. It shows attributes and operations in the objects of the system. The diagram represents ER diagram. The lines connecting the classes in the class diagram show relationships between the connected classes. Role-names and multiplicities that adorn the connecting lines describe association, aggregation or composition. Aggregation and composition are whole-part relationships. Other relationships may be dependency or generalisation. Dependency relationships involve the dependent class using the other class type parameter in method calls. Generalisation is an inheritance relationship. Messages are passed through the connecting lines in either direction unless navigation is specifically restricted to one direction. A system may require many class diagrams for its complete description. Special class types (<<stereotype>>) may be introduced. Object diagrams use instances, objects being shown by underlined names of instances and classes. Sometimes they may be anonymous.



Ananda Amatya
11/3/1999