FAQ on the solutions to Exercise 1

Contents:

  1. How do I know to which level of granularity I shall create/find objects?

  1. How do I know to which level of granularity I shall create/find objects?

Identify objects until you reach a level where the candidates are merely "value holders" without any behaviour which is relevant to the model. These "values holders" are the attributes.

However, an entity which is an attribute in one system could very well be an object in an other system.

Consider for example "destinationCity" in the solutions to the Airline Reservation System. If we consider this to be just a text string with the name of the city, then it is an attribute. But if we consider City objects to have behaviour, e.g. capable of calculating the distance to other City objects, then we would have to regard it as an object.