Object Oriented Data Model

Sep 26 • Notes • 1584 Views • No Comments on Object Oriented Data Model

  A data model is a logical organization of real world entities and relationships among objects. That data model which captures the object oriented concepts like encapsulation, abstraction, polymorphism, inheritance, etc. is called object oriented data model. An object oriented database is a collection of objects whose behavior, state and relationships are defined in accordance with an object oriented data model. Object oriented data model is based on the principles of object oriented programming. Object oriented data model encapsulates the data, hides it in the database and keeps it safe from outside interference.

 

Object Oriented Data Model

Object Oriented Data Model

Object oriented data model is a logical data model that captures the semantics of objects supported in an object oriented programming. It is a persistent and sharable collection of defined objects. It has the ability to model complete solution. Object oriented data model encapsulates the data, hides it in the database and keeps it safe from outside interference.Object oriented data models represent an entity and a class. A class represents both object attributes and as well as the behaviour of the entity.

Object oriented database
 An object oriented database is based on encapsulation of data and code related to on object into a single unit, which are not visible others. Therefore, object oriented data models emphasize on objects rather than data alone. These are useful for financial, telecommunications and World Wide Web applications. It is also suitable for multimedia applications as well as data with complex relationships over a relational DBMS.

 Characteristics of object oriented database
 As we know that object oriented database technology is a combination of object oriented programming and database technologies. There are different characteristics of an object oriented database.  The object oriented database combines the object oriented data model with the data stored inside database. It provides dynamic binding and polymorphism. There are many advantages to including the definition of operations with the definition of data. Object relational database has a large number of different data types and relationships between the objects. Second, the data type can be extended to support complex data such as multimedia by defining new object classes.

 Basic object oriented concepts on object oriented data model
 An object oriented data model consists of the following basic concepts.
(a)  Object and object identifier:- Any real world entity is uniformly modeled as an object.
(b) Attributes and methods:- Every object has a state and a behavior. The state and behavior encapsulated in an object are accessed or invoked from outside the object only through explicit message passing.
(c)  Class:- A class consists of all the objects which share the same set of attributes and methods. An object must belong to only one class as an instance of that class. A class is similar to an abstract data type. A class may also be primitive.
(d) Class hierarchy and inheritance:- In inheritance a new class is derived from an existing class. The new class is referred as the sub class or child class whereas the existing class is referred as the super class or parent class. The sub class inherits all the attributes and methods of existing class.

Difference between object oriented data model and physical data model
Object oriented data models are used to describe data and its relationships whereas physical data models are used for a higher-level description of storage structure and access mechanism. The object-oriented data models extend the definition of an entity to include not only the attributes but also the behaviour. Physical data model describes how data is stored in the computer, representing information such as record structures, record sequence and access paths.

 Encapsulation
 Encapsulation is an important object oriented methodology. It is the concept of data hiding. In encapsulation, the data in the database hides in the data set which keep them safe from misuse and outside interference.

 Structure of object oriented data model.
 The structure of object oriented data model is highly variable. Unlike traditional database, it has no single inherent database structure. The structure for any given class or type of object could be anything a programmer finds useful. For example, a linked list, a set, an array. An object main contain varying degrees of complexity, making use of multiple types and multiple structures.

 Benefits of object orientation in graphical user interface
The benefits of object orientation in Graphical user Interface (GUI) is as follows:
(a)  It facilitates the ability to create easy to use interface.
(b) It enhances the system user friendliness.
(c)  Object orientation makes it easier to define standards.

 Advantages of object oriented data model.
  The advantages of object oriented data model are as follows:
(a) More semantic information
(b) Support for complex objects
(c) Extensibility of data types.
(d) Improved performance with efficient caching
(e) Versioning
(f) Faster development and easy maintenance through inheritance and reusability
(g)  Technology driven product for next generation DBMS
(h) Potential to integrate DBMSs into a single environment.

 Disadvantages of object oriented database
The disadvantages of object oriented database are as follows:
(a) Lower efficiency when data is simple and relationships are simple.
(b) Relational tables are simpler
(c) Late binding may slow access speed
(d) More user tools exist for RDBMS.
(e) Standards for RDBMS is more stable.

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