Requirements

1
Requirements

• CS 361
• 1/23/07

2
Overview

• What are requirements?
• Where do requirements come from?
• Who are stake-holders?

3
Deriving requirements

• Potential sources
• Stake-holders
• Users
• Client
• Customers
• Other affected parties
• User studies (direct observation)
• Existing system design documentation
• Examining competing products
• Regulations/industry standards

4
Requirement classifications

• User vs. System vs. Domain
• What are the differences?
• Why do these differences matter?
• Functional vs Non-functional requirements
• What are the differences
• Why do these differences matter?

5
Common Problems with Requirements

• Split Requirements
• Consistency problem
• Completeness problem
• Ambiguity/lack of clarity problem
• Requirements amalgamation

6
Requirements Engineering Process

• What is a feasibility study, what is its purpose,
  what is its basic form?
• 4 steps of requirements engineering process
• Requirements discovery
• Requirements classification and organization
• Requirements prioritization and negotiation
• Requirements documentation

7
Requirements elicitation/analysis techniques

• Interviews
• Ethnography
• Scenarios
• Use-cases

8
Requirements Engineering techniques
Goal-Oriented Analysis

• Technique for requirements discovery,
  organization, and prioritization
• Basic idea, start breaking down the goals of
  the system into increasingly concrete and
  detailed requirements
• Goal task to be accomplished using the system
• Purpose is to ensure adequate requirements
  discovery

9
Requirements Engineering techniques
Goal-Oriented Analysis

• Advantages Even for large systems, the process
  is understandable and manageable
• Color coding used to identify system components
  responsible for goals

10
Requirements Engineering techniques
Goal-Oriented Analysis

• Technique allows for the discovery of
  vulnerabilities, or potential system problems
• Easy to apply, works well as a team technique,
  where different graphs are combined to offer
  better coverage

11
Requirements Engineering techniques
Goal-Oriented Analysis

• Finally, graph allows better prioritization by
  mapping dependencies and functional relationships.

12
Modeling requirements

• Data-flow model
• Composition model
• Architectural model
• Classification model
• State transition model

13
Exercise

• Split into groups of 3-4
• Do a goal-oriented analysis for an email client