12D.1
Object-Oriented Slide and Classical Software Engineering
Sixth Edition, WCB/McGraw-Hill, 2005
Stephen R. Schach
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CHAPTER 12 Unit D
Slide 12D.2
OBJECT-ORIENTED ANALYSIS
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Slide 12D.3
Continued from Unit 12C
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12.13 Extracting the Control Classes: The Osbert Oglesby Case Study
Slide 12D.4
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It is also usually easy to extract control classes
Each nontrivial computation is generally modeled by a control class
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In the case study there are four computations
Determining the maximum price that Osbert should offer for a
Masterpiece Masterwork, or Other painting
Determining if there is a new trend in art purchases
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Initial Control Classes: Osbert Oglesby (contd)
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Slide 12D.5
There are therefore four initial control classes
Figure 12.28
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12.14 Refining the Use Cases: The Osbert Oglesby CaseSlide 12D.6 Study
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The pricing algorithm treats the three types of paintings differently Use case Buy a Painting must therefore be refined into three separate use cases
Buy a Masterpiece Buy a Masterwork Buy Other Painting
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Refining the Use Cases: Osbert Oglesby (contd)
Slide 12D.7
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Use case Produce a Report also needs to be refined
The purchases report and the sales report use simple data extraction the future trends report involves computation All three reports use their own boundary classes
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For both these reasons, the Produce a Report use case must be refined into three use cases
Produce a Purchases Report Produce a Sales Report Produce a Future Trends Report
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Third Iteration of the Use-Case Diagram
Slide 12D.8
Figure 12.29
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Refining the Use Cases: Osbert Oglesby (contd)
Slide 12D.9
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Implications for the remaining UML diagrams include:
The description of the new Buy a Painting use case (see over) must be split into three separate descriptions The description of the Produce a Report use case must be split into three separate descriptions
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Use Case Buy a Masterpiece
Slide 12D.10
Figure 12.30
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Description of Use Case Buy a Masterpiece
Slide 12D.11
Figure 12.31
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Class Extraction (contd)
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Slide 12D.12
The description of class extraction is complete We now therefore return to the Unified Process
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12.15 Use-Case Realization: The Osbert Oglesby Case Study Slide 12D.13
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The process of extending and refining use cases is called use-case realization
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Use-Case Realization (contd)
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Slide 12D.14
The verb realize is used at least 3 different ways:
Understand (Harvey slowly began to realize that he was in the wrong classroom); Receive (Ingrid will realize a profit of $45,000 on the stock transaction); and Accomplish (Janet hopes to realize her dream of starting a computer company)
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In the phrase realize a use case, the word realize is used in this last sense
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Use-Case Realization (contd)
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Slide 12D.15
The realization of a specific scenario of a use case is depicted using an interaction diagram
Either a sequence diagram or collaboration diagram
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Consider use case Buy a Masterpiece We have previously seen
The use case The description of the use case
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12.15.1 Buy a Masterpiece Use Case
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Slide 12D.16
Class diagram (classes that enter into the use case)
Figure 12.32
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The Four Classes That Enter into This Use Case
Slide 12D.17
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User Interface Class
This class models the user interface
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Compute Masterpiece Price Class
This class models the computation of the price Osbert should offer
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Masterpiece Class
The computation involves comparing the masterpiece being considered with the masterpieces that have been previously auctioned
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Auctioned Painting Class
These masterpieces are all instances of Auctioned Painting Class
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Buy a Masterpiece Use Case (contd) Slide 12D.18
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The Seller does not interact directly with the software product
Instead, the Seller provides data Osbert that enters into the software product
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This is indicated in the note (the rectangle with the top right-hand corner turned over)
There is a dashed line from the note to the item to which it refers, the Seller in this case
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Buy a Masterpiece Use Case (contd) Slide 12D.19
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Scenario (one possible instance of the use case)
Figure 12.33
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Buy a Masterpiece Use Case (contd) Slide 12D.20
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An executing software product uses objects, not classes Example:
A specific masterpiece is not represented by Masterpiece Class but rather by an object, a specific instance of Masterpiece Class
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Such an object is denoted in UML by : Masterpiece Class
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Buy a Masterpiece Use Case (contd) Slide 12D.21
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A class diagram shows the classes in the use case and their relationships
It does not show the objects nor the sequence of messages as they are sent from object to object
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Something more is needed
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Buy a Masterpiece Use Case (contd) Slide 12D.22
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A collaboration diagram (of the realization of the scenario of the use case)
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Figure 12.34
Buy a Masterpiece Use Case (contd) Slide 12D.23
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Osbert will not approve the specification document unless he understands it Accordingly, a written description of the collaboration diagram is needed
The flow of events
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Buy a Masterpiece Use Case (contd) Slide 12D.24
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The flow of events of the collaboration diagram of the realization of the scenario of the use case
Figure 12.35
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Buy a Masterpiece Use Case (contd) Slide 12D.25
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UML supports two different types of interaction diagram
Collaboration diagram Sequence diagram
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Both contain exactly the same information, but displayed in different ways
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Buy a Masterpiece Use Case (contd) Slide 12D.26
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Sequence diagram equivalent to the collaboration diagram (of the realization of the scenario of the use case)
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Figure 12.36
Buy a Masterpiece Use Case (contd) Slide 12D.27
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The narrow rectangle on a lifeline (dashed vertical line) shows when the relevant object is active In the collaboration diagram, the [new] is inside the : Masterpiece Class object
In the sequence diagram, the object is shifted down so that its lifeline starts where the object is created
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Buy a Masterpiece Use Case (contd) Slide 12D.28
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The sequence diagram shows that every messag...