ACS2913 Software Requirements Analysis and Design · ACS2913 Software Requirements Analysis and Design Instructor: Victor Balogun EXTENDED REQUIREMENTS MODELING THE UNIVERSITY OF

ACS2913 Software Requirements Analysis and Design Instructor: Victor Balogun

EXTENDED REQUIREMENTS MODELING

THE UNIVERSITY OF WINNIPEG - ACS 2913 - FALL 2019 1

Chapter OutlineUse Case Descriptions

Activity Diagrams for Use Cases

The System Sequence Diagram—Identifying Inputs and Outputs

SSD Notation

Use Cases and CRUD

Integrating Requirements Models

SYSTEMS ANALYSIS AND DESIGN IN A CHANGING WORLD, 7TH EDITION – CHAPTER 5 ©2016. CENGAGE LEARNING. ALL RIGHTS RESERVED.

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Overview

Previous chapters identified and modeled the two primary aspects of functional requirements: use cases and domain classes

This chapter focuses on detail modelling for use cases to document the internal steps within a use case

Fully developed use case descriptions provide information about each use case, including:◦ actors, ◦ stakeholders, ◦ preconditions, ◦ post conditions, ◦ the flow of activities and ◦ exceptions conditions

Activity diagrams can also be used to show the flow of activities for a use case

Systems Analysis and Design in a Changing World, 7th edition – Chapter 5 ©2016. Cengage Learning. All rights reserved.

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Use Case Descriptions

Write a brief description as shown in Chapter 3 for most use cases.


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Brief Use Case DescriptionsA brief description can be used for very simple use cases, ◦ system to be developed is a small, well-understood application.

A simple use case would normally have a single scenario and very few—if any—exception conditions.

A brief description does not document the internal processing since for simple use cases there are few steps.


Use Case Descriptions

Write a fully developed use case description for more complex use cases

Typical use case description templates include:

1. Use case name2. Scenario (if needed)3. Triggering event4. Brief description5. Actors6. Related use cases (<<includes>>)7. Stakeholders8. Preconditions9. Postconditions10. Flow of activities11. Exception conditions


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Fully Developed Use Case Description

Use case: Create customer account


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Fully Developed Use Case Description Create customer account (part 1 )


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Fully Developed Use Case Description Create customer account (part 2 )

Use Case Description DetailsUse case name◦ Verb-noun

Scenario (if needed)◦ A use case can have more than one scenario (special case or

more specific path)

Triggering event◦ Based on event decomposition technique

Brief description◦ Written previously when use case was identified

Actors◦ One or more users from use case diagrams


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Use Case Description DetailsRelated use cases <<includes>>◦ If one use case invokes or includes another

Stakeholders◦ Anyone with an interest in the use case

Preconditions◦ What must be true before the use case begins

Post conditions◦ What must be true when the use case is completed◦ Use for planning test case expected results

Flow of activities◦ The activities that go on between actor and the system

◦ Usually the flow of activities is the most difficult part to develop, but also assists the analyst and the user to understand the requirements more deeply.

Exception conditions◦ Where and what can go wrong


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Another Fully Developed Use Case Description Example

Use caseShip items


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Fully Developed Use Case Description Ship items (part 1 )


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Fully Developed Use Case Description Ship items (part 2 )

Activity Diagrams for Use CasesActivity diagrams were introduced earlier as a technique for documenting user workflows.

They are easily understood diagram to document the workflows of the business processes.◦ Here we will used them to model processing as well.

Activity diagrams are also an effective technique to document the flow of activities within a use case◦ They are are helpful when the flow of activities for a use case is complex



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UML Activity Diagram for Use Case

Create Customer Account

Note: this shows flow of activities only


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Activity Diagram for Ship Items Use Case

Note:◦ Synchronization bar for

loop◦ Decision diamond


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UML Activity Diagram for Use Case

Fill shopping cart

Note: this shows use case with <<includes>> relationship

Summary


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This chapter focuses on models to provide details of use cases

Fully developed use case descriptions provide information about each use case, including actors, stakeholders, preconditions, post conditions, the flow of activities and exceptions conditions

Activity diagrams (first shown in Chapter 2) can also be used to show the flow of activities for a use case

Documents

ACS2913 Software Requirements Analysis and Design · ACS2913 Software Requirements Analysis and Design Instructor: Victor Balogun EXTENDED REQUIREMENTS MODELING THE UNIVERSITY OF