This document covers key concepts in object-oriented practices including abstraction, encapsulation, inheritance, polymorphism, and object modeling tips. It also discusses object-oriented data models, object-oriented database management systems (OODBMS), the OODBMS manifesto, object management architecture, and the common object request broker architecture. The document provides an agenda, definitions, and explanations of these important topics in 3 pages.

1. Chapter 25 - 28
Object-Oriented Practices

2. Agenda
• Object-Oriented Concepts
• Terminology
• Object-Oriented Modeling Tips
• Object-Oriented Data Models and DBMSs
• OODBMS Manifesto
• Object Management Architecture
• Common Object Request Broker
Architecture

3. Object-Oriented Concepts
• Abstraction – encapsulation and information
hiding
– Identifying the essential aspects of an entity (Object)
– Abstract Data Type (ADT): interface part (operation)
implementation part (data structure)
• Encapsulation
– An object has data structure and operations
• Information hiding
– Internal details
– Data independence

4. Terminology
• Object Identity
• Classes
• Operations, methods & messages
• Inheritance
• Polymorphism

5. Object Identity (OID)
• System generated
• Unique to that object
• Invariant
• Independent of the values of its attributes
• Invisible to the user
• Advantages:
– Fast, efficient, independent of content, not
changeable by user

6. Class
• Definition
– Group of objects with similar properties
(attributes), common behavior (methods),
similar relationship to other objects, and
common semantics.
• Diagram
– Box: class name, attributes, operations
(methods)
• Superclasses & subclasses
• Generalization & specialization

7. Inheritance
• Definition
– A subclass inherits the attributes, operations,
and association of its superclasses
• Types
– Single inheritance: one superclass
– Multiple inheritance: two or more superclasses
– Repeated inheritance: common superclass
– Selective inheritance: limited number of
properties from the superclass

8. Operations Methods & Messages
• Operations
– Function or procedure may be applied to or by
objects in a class
• Methods
– The implementation of an operation for a class
• Messages
– Communication between objects to execution
of a method

9. Link & Association - 1
• Link
– A physical or conceptual connection between
objects
– Link attribute describes property of an
association
• Association
– A description of a group of links with common
structure and common semantics
– Has a name (roles for problem description)
• A link is an instance of an association

10. Link & Association - 2
• Qualified association
– The objects in a many role are partially or fully
disambiguated by an attribute called the
qualifier
– A small box on the end of the association line
near the source class
• Multiplicity
– The number of instances of one class that may
relate to a single instance of an associated class
– one, many, zero or one

11. Polymorphism
• Overloading
– The name of a method to be reused within a
class definition or across class definitions
• Overriding
– The name of property to be redefined in a
subclass
• Dynamic binding
– Runtime determination of object and method

12. Object Modeling Tips
• Scope
• Simplicity
• Layout of diagram
• Name (descriptive, crisp, and unambiguous)
• Association (foreign keys)
• Multiplicity
• Qualifiers
• Review

13. Object-oriented DBMSs
• Object-oriented data model (OODM)
– A logical data model of objects supported in
object-oriented programming
• Object-oriented database (OODB)
– A persistent and sharable collection of objects
defined by an OODM
• Object-oriented DBMS (OODBMS)
– The manager of an OODB

14. OODBMS Manifesto - 1
• Support complex objects
• Support object identity
• Support encapsulation
• Support types or classes
• Support inheritance between types or
classes
• Support dynamic binding

15. OODBMS Manifesto - 2
• Completed computational DML
• Extensible data types
• Data persistence
• Support very large databases
• Support concurrent users
• Backup & recovery
• Support simple way of querying data

16. Object Management Architecture
(OMA)
• Object Model (OM)
– A design-portable abstract model for communicating with OMG
(Object Management Group)-compliant object-oriented systems
• Object Request Broker (ORB)
– Handles distribution of messages between application objects
(software bus)
• Object Services (concurrency control, security, persistence
etc.)
• Common Facilities (printing, e-mail etc.)
• Common Object Request Broker Architecture (CORBA)
– Enable client-server interaction with a specific implementation of
ORB

17. Points To Remember
• Object-Oriented Concepts
• Terminology
• Object-Oriented Modeling Tips
• Object-Oriented Data Models and DBMSs
• OODBMS Manifesto
• Object Management Architecture
• Common Object Request Broker
Architecture

18. Assignments
• Review chapters 5-6, 11-18, 25-27
• Read chapters 19 and 20
• Exam 3
– Date:
• Project
– Due date:
– Place:

19. End of MIS150
• Exam date: 12/9/03
• Study! Study! Study!
• Have a happy and safe holiday!!