1. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 1 The Movement Toward Objects Chapter 16

2. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 2 Key Definitions Object-oriented techniques view a system as a collection of self- contained objects which include both data and processes. The Unified Modelling Language (UML) has become an object modelling standard and adds a variety of techniques to the field of systems analysis and development.

3. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 3 The Object Approach and UML

4. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 4 Object Concepts An object is a person, place, event, or thing about which we want to capture information. Each object has properties (or attributes). The state of an object is defined by the value of its properties and relations with other objects at a point in time. Objects have behaviours -- things that they can do -- which are described by methods (or operations). Objects do not use primary or foreign keys, instead each instance is assigned a unique identifier (UID) when it is created.

5. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 5 An Object and Object Instances

6. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 6 Class A class is a general template we use to define and create specific instances or objects.

7. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 7 Classes and Objects

8. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 8 Inheritance Classes are arranged in a hierarchy Superclasses or general classes are at the top Subclasses or specific classes are at the bottom  Subclasses inherit attributes and methods from the superclasses above them Classes with instances are concrete classes Abstract classes only produce templates for more specific classes

9. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 9 Class Hierarchy

10. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 10 Inheritance

11. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 11 Messages Messages are information sent to objects to trigger methods

12. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 12 Polymorphism

13. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 13 Encapsulation The message is sent without considering how it will be implemented The object can be treated as a “black-box”

14. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 14 Benefits of an Object Approach An Object A class Inheritance Polymorphism Encapsulation What Do the Concepts Support and Lead To?

15. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 15 UML Defines a set of nine object diagramming techniques The key building block is the use case Diagrams are tightly integrated syntactically and conceptually to represent an integrated whole Application of UML can vary among organizations

16. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 16 Adaptation of the Phased Development Method

17. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 17 Use-Case Diagram

18. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 18 Use-Case Diagram Concepts Summarizes all use cases (for the part of the system being modelled) together in one picture Typically drawn early in the SDLC Shows the associations between actors and use cases

19. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 19 Integration of four UML Diagrams

20. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 20 Use Case Diagram for Appointment System

21. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 21 Syntax for Use-Case Diagram

22. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 22 Use-Case Diagram for Specialised Actor

23. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 23 Extends or Uses Associations

24. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 24 Steps in Creating the Use Case Diagram 1. Identify use cases 2. Draw the system boundary 3. Place use cases on the diagram G roup use cases into packages Add special use case associations 4. Identify the actors 5. Add Associations

25. PowerPoint Presentation for Dennis & Haley Wixom, Systems Analysis and Design Copyright 2000 © John Wiley & Sons, Inc. All rights reserved. Slide 25 Use-Case Diagram Example