1. Chapters 10, 11 SSD (Revision) SD DCD Exam Object-Oriented Design

2. Problem Statement: A customer wants to search for books written by a specific author from a library. The customer wants to specify an author, and gets the search results 2

3. Approach: Chapter 11: “Advanced design is based on the concepts of use case realization by using Sequence diagrams and Design patterns Once you become proficient with these two subjects, you are an OO designer 3

4. Use case: Components: Actor Use case (What the system must do) First: The EVENT table 4

5. 5 EventTypeTriggerSourceUse CaseResponseDestination

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8. Background: Object-oriented analysis models were discussed in Chapters 2 - 5 Chapter 10, the fundamental principles: A complete coverage of design principles and skills to at least do basic object-oriented design Chapter 11 presents more advanced concepts particularly for detailed design with use case realizations: enhanced detailed design skills, and concepts related to design patterns, which are critically important for programming. 8

9. Foundation: Object-oriented design is a process by which a set of detailed object-oriented design models are built and then used by the programmers to write and test the new system. One of the strengths of the object-oriented approach is that the design models are often just extensions of the requirements models. 9

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11. Question: The previous slide shows the artefacts. Don’t confuse with waterfall approach: What is our SDLC? What is agile development? Iterative development? 11

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13. Notation SSD: 13

14. 14 Message Notation

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16. Use Case Controller An artifact invented by the designer to handle a system function Serves as a collection point for incoming messages Intermediary between the outside world and the internal system 16

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18. Designing with Sequence Diagrams An SSD captures the interactions between the system and the external world represented by actors The system is treated like a black box A detailed sequence diagram (SD) uses all of the same elements as an SSD The :System object is replaced by all of the internal objects and messages within the system 18

19. Guidelines for Preliminary Sequence Diagram Development Determine all of the internal messages that result from each input message Define origin and destination objects Identify the complete set of classes that will be affected by each message Flesh out the components for each message Iteration, true/false conditions, return values, and passed parameters 19

20. Developing a Multilayer Design View layer Design the user interface for each use case Develop dialog designs for forms Add the window classes to the sequence diagram Data access layer Initialize domain objects with data from the database Query the database and send a reference object Return information in the reference object 20

21. Search for Author: The Customer specifies an author on the “Search Page” and then presses the Search button The system validates the Customer’s search criteria The system searches the Catalogue for books associated with the specified author When the search is complete, the system displays the search results. 21

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23. O-O program The previous slide shows how an object- oriented program works. Hidden, it also illustrates the three-layer architecture: Abstract Three Layer Architecture 23

24. Objective of O-O design: The objective of object-oriented design is to identify and specify all the objects that must work together to carry out each use case. As shown in Figure 10-1, these objects include user-interface objects, problem domain objects, and data access objects. Can you identify these objects? 24

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26. The OO diagrams: O-O analysis: Use case, Use case description, Activity diagram, Domain Model Diagrams, System Sequence Diagram, State Machine Diagram O-O design: Component diagrams, deployment diagrams, design class diagrams, interaction diagrams, state machine diagrams, and package diagrams. 26

27. Revision: An object class (or a class) is… Set of people Places Things Or transactions that share common attributes and perform common functions to help an organization reaches its goals. 27

28. Examples: People: employees, vendors, customers Places: warehouses, office, branches, shipping docks Things: products, office equipment, supplies Transaction: purchases, sales, returns, payments 28

29. Example: Draw money from ATM Processes: Insert credit card Enter PIN Enter Amount What happens behind UI? Verification from bank system …… 29

30. Classes? Customer ATM: ATM System Bank System 30

31. Interaction: What message/communication takes place between customer and ATM? Introducing Design Class Diagram: Customer wants to enter PIN If verified, Customer wants to draw money 31

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34. Three layer Architecture: user-interface objects, problem domain objects, and data access objects. 34

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36. Two Things (p284-287): Identifying design classes: use interactions to add operations to classes. Identifying stereotypes ( >)in UML models: Entity class Boundary class Control class Data access class 36

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39. Steps to follow: Develop use case, use case description, activity diagram: Domain class diagram, SSD Draw the SD Sort-out the interactions or messages Add the operations/behaviour Can you identify the ‘three layer diagram’? 39

40. Exam: Q1: p264, problems 1, 2, 3:system vision document Q2: project management: NPV, Payback period, graph, ROI: pr 4, 5, 6, 7 Q3:Network diagram Q4:UI design. Going to include blocks AppInv Q5: SD Q6: DCD 40