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Chapter 25 - 28

Chapter 25 - 28. Object-Oriented Practices. 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. Object-Oriented Concepts.

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Chapter 25 - 28

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  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!!

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