Many object-oriented applications store data in a relational database and use a conversion routine to translate data from data members of objects into rows in a relational database and to transfer data from a relational database to data members of objects.
Objects are thought of as nouns, such as a person, place, or thing. Tasks are thought of as verbs because they describe actions within an application.
Some business applications cannot be organized easily into discrete objects, which posses a challenge for programmers.
A dynamic hierarchy is an organization of objects in which the relationship among the objects is changed over a short timeframe.
A static hierarchy is an organization of objects in which the relationship among objects is maintained over time.
A hierarchy is morphed when a member function has many versions of a behavior requiring many overloaded functions.
Some programmers feel we view the world as tasks rather than as objects. For example, we think to turn on the air conditioner in hot weather, which is a task. We dont think air conditioner, turn on, which is the object-oriented logical approach.
Object-oriented programming theory assumes that the real world is organized neatly into objects that can be defined easily as objects in an object-oriented application. Some aspects of the real world can be defined as objects; other aspects of the real world dont lend themselves to such a definition.
Yes, the goal of an object-oriented program is to simulate real-world objects in a computer application. However, many business applications do not simulate real-world business situations. The reality is that simulating the real world does not necessarily use the best possible means to achieve a business objective.
An internal model describes how an application works behind the scenes. An external model describes how a person interacts with the application.