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!!