Contrasts with attribute-centred modelling. A discovery procedure for establishing the limits of system requirements. The ordering of classes in a hierarchy, according to their similarities and differences. Cohesion Describes how strongly a collection of parts belong together. A set of attributes storing the name, age and sex of a Person are highly cohesive, whereas a method which performs two unrelated tasks has low cohesion.
Good designs have high cohesion.
Coupling Describes how strongly two classes are interdependent. If one calls many of the other's methods , they are strongly coupled. If there are few interactions between them, they are weakly coupled. Good designs have weak coupling. Forces the decentralisation of system control and aids in identifying new classes of object .