Introduction to Object Oriented databases

Department of Information Technology 1Data base Technologies (ITB4201)
Introduction to Object Oriented Databases
Dr. C.V. Suresh Babu
Professor
Department of IT
Hindustan Institute of Science & Technology

Action Plan
• Object Oriented Databases
• Object Oriented Data Model(OODM)
• Characteristics of Object oriented database
• Object, Attributes and Identity
• Object oriented methodologies
• Benefit of object orientation in programming
language
• Object oriented model vs Entity Relationship model
• Advantages of OODB over RDBMS
• Quiz

Object Oriented Database
• When the database techniques are combined with object oriented concepts, the
result is an object oriented management system (ODBMS).
• Today’s trend in programming languages is to utilize objects, thereby making
OODBMS is ideal for Object Oriented programmers because
– they can develop the product,
– store them as objects, and
– can replicate or modify existing objects to make new objects within the OODBMS.
• Object databases based on persistent programming acquired a niche in
application areas such as
– engineering and spatial databases,
– telecommunications, and
– scientific areas such as high energy physics and molecular biology.

Object Oriented Database Standards
Some of the Object oriented DBMS standards are
• Object data management group
• Object database standard ODM 6.2.0
• Object query language
• Object query language support of SQL 92

Object Oriented Data Model(OODM)
• Object oriented data models are a logical data models that capture the
semantics of objects supported on object oriented programming.
• OODMs implement conceptual models directly and can represent
complexities that are beyond the capabilities of relational systems.
• OODBs have adopted many of the concepts that were developed originally
for object oriented programming language.
• An object oriented database is a collection of objects defined by an object
oriented data model.
• An object oriented database can extend the existence of objects so that
they are stored permanently.
• Therefore, the objects persist beyond program termination and can be
retrieved later and shared by other programs.

Characteristics of Object oriented database
The characteristics of object oriented database are listed below.
• It keeps up a direct relation between real world and database objects as if
objects do not loose their integrity and identity.
• OODBs provide system generated object identifier for each object so that
an object can easily be identified and operated upon.
• OODBs are extensible, which identifies new data types and the operations
to be performed on them.
• Provides encapsulation, feature which, the data representation and the
methods implementation are hidden from external entities.
• Also provides inheritance properties in which an object inherits the
properties of other objects.

Object, Attributes and Identity
• Attributes : The attributes are the characteristics used to describe objects.
Attributes are also known as instance variables. When attributes are
assigned values at a given time, it is assumed that the object is in a given
state at that time.
• Object : An object is an abstract representation of the real world entity
which has a unique identity, embedded properties, and the ability to
interact with other objects and itself.
• Identity : The identity is an external identifier- the object ID- maintained
for each object. The Object ID is assigned by the system when the object is
created, and cannot be changed. It is unlike the relational database, for
example, where a data value stored within the object is used to identify
the object.

Object oriented methodologies
There are certain object oriented methodologies are use in OODB. These are:
• Class: A class is assumed as a group of objects with the same or similar attributes
and behavior.
• Encapsulation: It is the property that the attributes and methods of an object
are hidden from outside world. A published interface is used to access an
object’s methods.
• Inheritance: It is the property which, when classes are arranged in a hierarchy,
each class assumes the attributes and methods of its ancestors. For example,
class students are the ancestor of undergraduate students and post graduate
students.
• Polymorphism : It allows several objects to represent to the same message in
different ways. In the object oriented database model, complex objects are
modeled more naturally and easily.

Benefit of object orientation in programming
language
The benefits of object orientation in programming language are:
• Minimizes number of lines of code
• Reduces development time
• Increases the reusability of codes
• Makes code maintenance easier
• Increased productivity of programmers

Merits of Object oriented database
OODBs provide the following merits
• OODBs allow for the storage of complex data structures that
cannot be easily stored using conventional database
terminology.
• OODBs support all the persistence required for object oriented
applications.
• OODBs contain active object servers which support both
distribution of data and distribution of work.

Advantages of Object oriented data model over
Relational model
When compared with the relational model, the object oriented
data model has the following advantages.
• Reusability: generic objects can be defined and then reused in
numerous application.
• Complex data types: Can manage complex data such as
document, graphics, images, voice messages, etc.
• Distributed databases: Due to mode of communication
between objects, OODBMS can support distribution of data
across networks more easily.

Object oriented model vs Entity Relationship
model
• An entity is simply a collection of variables or data items.
• When an application is running, the ER Model will tells how
the application’s data will be persisted but the Object Oriented
Model will decide that how that data will be stored in the
memory.

Advantages of OODB over RDBMS
Object oriented database advantages over RDBMS:
• Objects do not require assembly and dis-assembly saving coding
time and execution time to assemble or disassemble objects.
• Reduced paging
• Easier navigation
• Better concurrency control
• Data model is based on the real world
• Works well for distributed architectures
• Less code required when applications are object oriented.

Test Yourself
1. Which of the following is true concerning on ODBMS
a. They have the ability to store complex data types on the Web.
b. They are overtaking RDBMS for all applications.
c. They are most useful for traditional, two-dimensional database table applications.
d. All of the above.
2. Using ODL, you can define which of the following?
a. Attribute
b. Structure
c. Operation
d. All of the above
3. The object definition language (ODL) is which of the following?
a. Used to develop logical schemas
b. A data definition language for OODB
c. A method to implement a logical schema
4. In an object-oriented model, one object can access data of another object by passing:
a. Instance variable
b. Message
c. Variable
d. None of these
5. Which of these simplifies an Object Relational Mapping tool?
a. Data creation
b. Data manipulation
c. Data access
d. All mentioned above

1. Which of the following is true concerning on ODBMS
a. They have the ability to store complex data types on the Web.
b. They are overtaking RDBMS for all applications.
c. They are most useful for traditional, two-dimensional database table applications.
2. Using ODL, you can define which of the following?
a. Attribute
b. Structure
c. Operation
d. All of the above
3. The object definition language (ODL) is which of the following?
a. Used to develop logical schemas
b. A data definition language for OODB
c. A method to implement a logical schema
4. In an object-oriented model, one object can access data of another object by passing:
a. Instance variable
b. Message
c. Variable
d. None of these
5. Which of these simplifies an Object Relational Mapping tool?
a. Data creation
b. Data manipulation
c. Data access
d. All mentioned above
Answers

Introduction to Object Oriented databases

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