In this chapter we study an overview of the object-oriented database model - including UML.

In this chapter we will examine object-oriented databases. An object oriented database is structured like an object oriented language.

Unified Modeling Language (UML) is a set of graphical notations backed by a common metamodel that is widely used both for business modeling and for specifying, designing,

and implementing software systems artifacts.

 

The following are definitions used for object-oriented databases:

Class

An entity type that has a well-defined role in the application domain about which the organization wishes to maintain state, behavior, and identity.

 

Object

An instance of a class that encapsulates data and behavior.

 

State

An object’s properties (attributes and relationships) and the values those properties have

 

Behavior

The way in which an object acts and reacts.

 

Class diagram

A diagram that shows the static structure of an object-oriented model: the object classes, their internal structure, and the relationships in which they participate

 

Object diagram

A graph of objects that are compatible with a given class diagram

 

Operation

A function or a service that is provided by all the instances of a class.

 

Encapsulation

The technique of hiding the internal implementation details of an object from its external view.c

 

Constructor operation

An operation that creates a new instance of a class.

 

Query operation

An operation that accesses the state of an object but does not alter the state

 

Update operation

An operation that alters the state of an object.

 

Class-scope operation

An operation that applies to a class rather than to an object instance.

 

Association

A named relationship between or among object classes.

 

Association role

The end of an association, where it connects to a class.

 

Polymorphism

The ability of an operation with the same name to respond in different ways depending on the class context.

 

Overriding

The process of replacing a method inherited from a superclass by a more specific implementation of that method in a subclass