Transcript Investigating System Requirements

Investigating System
Requirements
Chapter 2 pp: 35-57
Where are we?
Analysis Chapters
Ch 2 Investigating System Requirements
Ch 3 Use Cases
Ch 4 Domain Modeling
Ch 5 Extending the Requirements Model
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Outline
 Stakeholders
 SDLC Core Process 3 – Analysis
 Information Gathering Techniques
 Types of Requirements
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FURPS+
Stakeholders
" W h o d o y o u invo lve a n d ta lk to ?"
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Internal Stakeholders
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External stakeholders
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Operational stakeholders
- regularly interact with system
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Executive stakeholders
- don’t directly interact but ..
- use the info , or
- have financial interest
SDLC Phase: Analysis
 Core Process 3:
Discover & understand details
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SDLC Phase: Analysis
 Gather detailed info
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Information Gathering Techniques
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Why do we use different Techniques?
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Interviews
Observation
Review documents & procedures
Questionnaires
Research vendor solutions
User feedback
Formal Systems
Informal Systems
Information Gathering
Techniques
 Interviews
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Interview users & other key stakeholders
Effective way to understand business
functions and rules
- Disadvantage
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time consuming
resource expensive
Tips:
Plan the interview
Interview several key people together (pros & cons)
Listen carefully and take notes
Be neutral
- Seek diverse views
- Stay on schedule
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Information Gathering
Techniques
 Observations
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Direct Observation
Watching users do their jobs
Firsthand & objective
- Disadvantage
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People may change their normal operating behavior.
Time-consuming
Information Gathering
Techniques
 Review Documents
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Existing business documents
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Forms, reports, work procedures
Input & outputs
Types of information to be discovered:
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& Procedures
Reasons for current system design
Rules for processing data
Problems with existing system
Discrepancies, Redundancies
Opportunity to meet new need
Special information processing
circumstances
Information Gathering
Techniques
 Questionnaires
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Used with a large number of stakeholders
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Closed-ended & open-ended questions
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Quantitative data vs. Qualitative data
 Research
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Vendor Solutions
Many problems have been solved by other companies
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+ provide new ideas, cheaper, less risky
- may purchase before understanding problem
 User Feedback
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Collecting feedback after initial testing
Comments & suggestions
SDLC Phase: Analysis
 Define requirements
 System Requirements - (def) specifications that define the new
system
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Functional
Functional Requirements - activities the system must perform
Non-Functional Requirements - constraints and performance goals
Usability
requirements requirements
• UI Design
• Navigation
• Help Doc.
Reliability
Performance Security
requirements requirements requirements
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Avail. reqs
Detection
Backup
recovery
• Response time
real time
-batch
Model - a representation of some aspect of
a system
 Textual model
 Graphical models
 Mathematical models
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• Data storage
• Data transmission
• Encryption
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SDLC Phase: Analysis
 Prioritize
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requirements
High vs. low priority
Scope creep
 Develop UI Dialogs
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Prototype
Can be better than an abstract model
 Evaluate
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Requirements with users