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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.

An Introduction toObject-Oriented

Systems Analysis and Design with UML and

the Unified Process

McGraw-Hill, 2004

Stephen R. Schach

srs@vuse.vanderbilt.edu

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Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.

CHAPTER 7 — Unit A

THE ANALYSIS WORKFLOW II

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Chapter Overview

Extracting Entity Classes: MSG Foundation Case Study

Initial Functional Model: MSG Foundation Case Study

Initial Class Diagram: MSG Foundation Case Study Back to the Requirements Workflow Initial Dynamic Model: MSG Foundation Case Study Revising the Entity Classes: MSG Foundation Case

Study Extracting Boundary Classes: MSG Foundation

Case Study

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Chapter Overview (contd)

Extracting Control Classes: MSG Foundation Case Study

Use-Case Realization: MSG Foundation Case Study Incrementing the Class Diagram More on Actors More on Use Cases Risk Rapid Prototyping Scenarios and the Client’s Needs

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Extracting Entity Classes: MSG Foundation

Entity class extraction is performed by iterating three steps– Functional modeling– Class modeling– Dynamic modeling

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Extracting Entity Classes: MSG Foundation

The first step is to perform functional modeling

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Initial Functional Model: MSG Foundation

The seventh iteration of the use-case diagram

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Manage a Mortgage Use Case

One possible extended scenario

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Manage a Mortgage Use Case (contd)

A second extended scenario

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Estimate Funds Available for Week Use Case

One possible scenario

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Produce a Report Use Case

One possible scenario

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Produce a Report Use Case (contd)

Another possible scenario

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Class Modeling

The second step of entity class extraction is class modeling– The two-stage noun extraction method is used

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Noun Extraction: MSG Foundation

Stage 1: Describe the information system in a single paragraph– Weekly reports are to be printed showing how much

money is available for mortgages. In addition, lists of investments and mortgages must be printed on demand.

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Noun Extraction: MSG Foundation (contd)

Stage 2: Identify the nouns in this paragraph– Weekly reports are to be printed showing how much

money is available for mortgages. In addition, lists of investments and mortgages must be printed on demand.

The nouns are report, money, mortgage, list, and investment

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Noun Extraction: MSG Foundation (contd)

Nouns report and list are not long lived, so they are unlikely to be entity classes (report will surely turn out to be a boundary class),

money is an abstract noun

This leaves two candidate entity classes– Mortgage Class and Investment Class 

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First Iteration of the Initial Class Diagram

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Second Iteration of the Initial Class Diagram

Operations performed on the two entity classes are likely to be very similar– Insertions, deletions, and modifications

All members of both entity classes have to be printed on demand– Mortgage Class and Investment Class should be

subclasses of a superclass called Asset Class

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Second Iteration of Initial Class Diagram (contd)

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Back to the Requirements Workflow

The current 5 use cases include Manage a Mortgage and Manage an Investment

These can now be combined into a single use case, Manage an Asset

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Eighth Iteration of the Use-Case Diagram

The new use case is shaded

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Second Iteration of Initial Class Diagram (contd)

Now the attributes are added

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Iteration and Incrementation

The phrase “iterate and increment” also includes the possibility of having to decrement what has been developed to date– A mistake may have been made, and backtracking is

needed– As a consequence of reorganizing the UML models, one

or more artifacts may have become superfluous

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Initial Dynamic Model: MSG Foundation

The third step is dynamic modeling– A statechart is drawn that reflects all the operations,

showing the events that cause the transition from state to state

The major source of information regarding the relevant operations is the scenarios

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Statechart: MSG Foundation Case Study

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Statechart: MSG Foundation Case Study (contd)

The statechart reflects the operations of the complete MSG Foundation information system– The solid circle on the top left represents the initial state,

the starting point of the statechart– The white circle containing the small black circle on the

top right represents the final state– States other than the initial and final states are

represented by rectangles with rounded corners– The arrows represent possible transitions from state to

state

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Statechart: MSG Foundation Case Study (contd)

In state MSG Foundation Information System Loop, one of five events can occur

An MSG staff member can issue one of five commands: – estimate funds for the week– manage an asset– update estimated annual operating expenses– produce a report, or– quit

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Statechart: MSG Foundation Case Study (contd)

These possibilities are indicated by the five events – estimate funds for the week selected– manage an asset selected– update estimated annual operating expenses selected– produce a report selected, and – quit selected

An event causes a transition between states

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Statechart: MSG Foundation Case Study (contd)

An MSG staff member selects an option by clicking on the menu

This graphical user interface (GUI) requires special software

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Statechart: MSG Foundation Case Study (contd)

Here is an equivalent textual user interface that can run on any computer

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Statechart: MSG Foundation Case Study (contd)

Example:– The MSG staff member clicks on the choice Manage an

asset – The event “manage an asset selected” has now occurred– The system moves from its current state, MSG

Foundation Information System Loop, to the state Managing an Asset

– The operations that the MSG staff member can perform in this state» Add, delete, or modify a mortgage or investment

appear below the line in the box with rounded corner

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Revising the Entity Classes: MSG Case Study

The initial functional model, the initial class diagram, and the initial dynamic model are completed– Checking them reveals a fault

In the initial statechart, consider state Update Estimated Annual Operating Expenses with operation Update the estimated annual operating expenses– This operation has to be performed on the current value of

the estimated annual operating expense

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Revising the Entity Classes: MSG (contd)

But where is the value of the estimated annual operating expenses to be found?

Currently there is only one class (Asset Class) and its two subclasses– Neither is appropriate for storing the estimated annual

operating expenses

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Revising the Entity Classes: MSG (contd)

The only way a value can be stored on a long-term basis is as an attribute of an instance of that class or its subclasses

Another entity class is needed in which the estimated annual operating expenses can be stored– MSG Application Class

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Third iteration of the initial class diagram: MSG

MSG Application Class has other attributes as well– Attributes

that do not appertain to the assets

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Continued in Unit 7B