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Requirements Management with Use Cases
Module 10: Requirements Across the Product Lifecycle
Requirements Management with Use Cases
Module 10: Requirements Across the Product Lifecycle
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 2
Objectives: Requirements Across the Lifecycle
Describe the state of a use-case model at the end of each phase of the lifecycle
Explain an iteration assessment Identify the types of requirements reviews Describe how requirements drive analysis
and design Describe how requirements drive test
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 3
Requirements Across the Product Lifecycle
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 4
Inception Iterations: Typical Requirements ResultsCollect information to develop the business case:
A draft of a survey of the use-case model An initial vocabulary A few use-case flows of events (requirements capture) Sketches of user interfaces A prototype (optional) Approximately 10% of schedule time Approximately <5% of person hours
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 5
L P
I DU
Elaboration Iterations: Typical Requirement ResultsRefine requirements to build/validate architecture
Update terminology Capture most software requirements
• Use cases and supplementary specifications Refine use cases developed in previous iterations Decide on use-case view of the architecture Approximately 30% of schedule time Approximately 20% of person hours
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 6
Construction Iterations: Typical Requirement ResultsBuild the complete system
Change requests on use-case’s flow of events Updated use-case flow of events Emphasis on analysis, design, implementation and test Approximately 50% of schedule time Approximately 65% of person hours
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 7
Transition Iterations: Typical Requirements Results
Requirements should not change Similar to typical construction-phase iteration if
new features are added Approximately 10% of schedule time Approximately 10% of person hours
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 8
Iteration Assessment Apply evaluation criteria
Functionality Performance Capacity Quality measures
Consider external changes Examples: changes to requirements, user
needs, competitor’s plans Determine what rework, if any, is required Assign rework to remaining iterations
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 9
Reviewing Requirements
Informal reviews To find errors Whenever needed Small team, possibly including QA
Formal reviews To decide whether to proceed to
next phase At milestones and tollgates Large reviewing team, including
customers
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 10
Types of Reviews
Walkthrough
Inspection
Formal review
Less Formal
More Formal
IEEE, 1994
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 11
Review Requirements: Walkthrough
Purpose Find errors in an early stage Find deviations from approved style, technique,
standards Informing
Participants A few project members, need not be prepared
Procedure Analyst gives an overview of the results Analyst walks through reviewed chapters, other
participants comment Analyst makes notes on errors found
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 12
Review Requirements: Inspection
Purpose To share views from different parts of the organization To find errors and problems early To make approval, revision, or rejection decisions
Participants Moderator, recorder, author, and inspectors
Procedure Organize before the meeting Keep meeting focused (moderator) Record all issues (recorder) Look for and discuss errors (Inspectors)
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 13
Review Requirements: Formal Review
Purpose To ensure that results are complete and
consistent To decide on continuation of project
Participants Top management, project leaders, process
owners, analysts Procedure
Check status of documents (evaluation results) Review outcome of the project Authorize start of next phase
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 14
How Do Requirements Drive Development?
Verified byRealized by Implemented by
Implementation Model Test ModelDesign Model
Use-Case Model
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 15
Requirements Drive Design and Implementation
Analysisand DesignAdd detail and
design decisions
Developer Perspective
Use CasesDevelop model of requirements
User Perspective
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 16
Use-Case Realization
Use Case
Sequence Diagrams
Collaboration Diagrams
Analysis/Design Defines Classes and Interactions
For each use-case flow of events, show interactions in interaction diagrams
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 17
Requirements Drive Test
TestAdd detail and
test case decisions
Tester Perspective
Use CasesDevelop model of requirements
User Perspective
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 18
Scenario 1: Happy Day Flow
Customer logs on Customer selects ‘Trade’ Customer selects account Customer performs trade
Select ‘Market Buy Order’ Enter Asset Purchase Information System sends Market Buy Order to Marketing
Trading System and receives confirmation Display Confirmation of Trade
Customer logs off
Execute TradeTrading
Customer
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 19
Scenario 2: Alternative Flow, Insufficient Cash
Customer logs on Customer selects ‘Trade’ Customer selects account Customer performs trade
Select ‘Market Buy Order’ Enter Asset Purchase Information System determines not enough cash in account Notify customer that account has insufficient
funds Customer logs off
TP8:Test Plan Template
Execute TradeTrading
Customer
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 20
Review: Requirements Across the Product Lifecycle
1. What is the typical state of a use-case model at the end of each phase of the lifecycle?
2. Under what circumstances would you change anything in the use-case model during the transition phase?
3. What is the purpose and contents of an iteration assessment?
4. What are the different types of reviews? When might each be used?
5. How do requirements drive design?6. How do requirements drive test?
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 21
Summary (1 of 2)
Build the right system right by using a process to define and manage requirements to meet the customer’s needs
Effective problem analysis helps avoid the “Yes, but…”
Elicitation helps you understand your stakeholders’ needs
Use features and a use-case model to gain agreement with the customer on the definition of the system
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 22
Summary (2 of 2)
Increase your chances to deliver on time and on budget by managing scope throughout the lifecycle of the project
A use-case model of requirements helps refine the system definition to drive design, test, and user documentation
Requirement attributes and traceability help you manage change and avoid “scope creep”
Requirements Management with Use CasesCopyright © 1998-2001 Rational Software, all rights reserved 23
Applying RMUC Concepts: Handouts
Summary: Key Skills for Requirements Management White Paper: Applying Requirements Management
with Use Cases
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