Object Oriented Analysis (Coad-Yourdon)

Object Oriented Software Engineering
Object-Oriented Analysis
(Coad-Yourdon)

1. Object-Oriented Analysis ( Coad-Yourdon) Subash Khatiwada 1 st semester MSc.CSIT, CDCSIT, Kritipur

2. OOA- Introduction Object Oriented Analysis is an analysis model developed to describe the functionality of the system. Peter Coad and Edward Yourdon described step by step method for developing object oriented system models in 1991.

3. Why do we need Object Oriented Analysis? Tackle more challenging problem domains. Improve analyst and problem domain expert interaction. Increase the internal consistency of analysis results. Explicitly represent commonality. Build specifications resilient to change. Reuse analysis results. Provide a consistent underlying representation for analysis.

4. Five major activities of OOA Finding Class & Objects Identifying Structures Identifying Subjects Defining Attributes Defining Services

5. [1] Finding Class & Objects Class & objects within a problem domain and within the context of a system’s responsibilities are identified. Where to look? Observe first-hand Actively listen to problem domain experts Check previous OOA results Check other systems Prototype Read, Read, Read 

6. Graphical Notation Representing Aircraft in class notation

7. [2] Identifying Structures Overall structures of system is identified by two terms: Generalization and Specialization (Gen-Spec) Structure It captures the inheritance hierarchy among identified classes. Whole-Part Structure Whole-part structure is used to model how an object is part of another object and how an objects are grouped into larger categories.

8. Example: Gen-Spec Structure

9. Example: Whole-Part Structure an aircraft is an assembly of possibly no engine (a glider!) at most four engines and an engine is part of possibly no aircraft at most one aircraft

10. [3] Identifying Subjects Identifying subjects is done by partitioning the Class & Objects model into larger units. Subjects are groups of Class & Objects. Subjects are defined after identifying system’s structures.

11. [4] Defining Attributes Defining attributes is done by identifying information and associations that should be associated with each and every instance.

12. Example: Instance Connection A particular fight plan must be assigned for exactly one aircraft, any particular aircraft may have zero or many flight plans.

13. [5] Defining Services Defining services means defining the operation of the classes, this is done by identifying the object states and defining services such as create, access, connect, display and so on. How the objects communicate with messages is identified using message connections.

14. Strategy – Defining Services Identifying Object States Identify the required Services Identify the Message Connections Specify the Services  eg. Radar.SerachAirSpace () Put the OOA documentation set together

15. Example Real Time Airlift System (RTAS)

16. [1] Finding Class & Objects

17. [2] Identifying Structures

18. [3] Identifying Subjects

19. [4] Defining Attributes

20. [5] Defining Services

21. OOA Multilayer Model Object Oriented Analysis can be presented in five layers: Subject Layer Class & Object Layer Structure Layer Attribute Layer Service Layer

22. Thank you!