Requirements Overview cont'

1
Requirements Overview (cont.)

• Requirements Analysis
• Documentation

2
Requirements Elicitation

• Techniques
• Interview / Meeting
• Survey / Questionnaire
• Observation
• Ethnography / Temporary Assignment
• Business Plans
• Review Internal / External Documents
• Review Software

3
Requirements Analysis

• Goal
• To bridge the gap between the problem domain and
  the technical domain
• Tasks
• Problem Recognition
• Evaluation and synthesis
• Modeling
• Specification
• Review

4
Requirements Review?

• Are the requirements complete?
• Are the requirements concise?
• Are the requirements correct?
• Are the requirements consistent?
• Are the requirements modular? Can they
  accommodate change?
• Are the requirements realistic?
• Is the requirement needed by the customer?
• Are the requirements traceable?

5
Requirements Specification

• Goal
• To provide a representation of the software for
  the customers review and approval
• Developed as a joint effort between the developer
  and the customer
• Serve as basis for review for both customer and
  developer
• Culmination of requirements analysis

6
Software Requirements Specification (SRS)

• Includes Requirements Definition Specification
• Principles Heninger 80
• Should specify external system behavior
• Should specify implementation constraints
• Should by easy to change
• Should serve as reference tool for maintenance
• Should record forethought about system lifecycle
• Should characterize acceptable responses to
  undesired events

7
Software Requirements Specification (SRS)

• Introduction
• Project Overview
• Problem Statement
• System Models
• Information Model
• Functional Model
• Behavioral Model
• Functional Requirements Definition

• Non-functional Requirements Definition
• System Evolution
• Requirement Specification
• Validation Criteria
• Bibliography
• Appendix Glossary

8
Software Project Management

• Project Management
• Project Planning

9
Project Management

• Goals
• Software delivered within budget
• Software delivered within schedule
• Software is built according to requirements
• Why?
• Well-managed projects sometimes fail
• Badly managed projects inevitably fail
• Software development process is not standardized

10
Project Manager Responsibilities

• Proposal Writing
• Project Costing
• Project Planning Scheduling
• Project Monitoring Reviews
• Personnel Selection Evaluation
• Report Writing Presentations

Sommerville, 1995
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Project Planning Process
Sommerville, 1995
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So how do we do this?

• Spend time understanding the problem
• Estimate amount of effort required
• Number of major functions
• Difficulty of each function
• Develop schedule with built in safety nets
• Increase estimates by some factor
• Have a backup plan for worst case
• Make sure schedule is realistic
• Revise schedule as project understanding
  increases

13
Estimation Overview

• Difficult error prone
• Gradual refinement
• At beginning of project, have a fuzzy idea of
  problem, therefore estimate of time and effort
  will be fuzzy too
• Only as the project develops and the problem and
  solution become clearer, will the estimates
  increase in accuracy

• Estimation Process
• Estimate the size of the product
• Lines of code (LOC)
• Function Points
• Number of functions
• Estimate the effort
• Person-months
• Estimate the schedule
• Calendar time

14
From Estimation to Scheduling

• Refinement
• Initial problem statement
• Requirements Specification
• High Level Design
• Detailed Design Specification
• Implementation

• Cases
• Best Case
• Most Likely Case
• Current Case
• Worst Case

15
Scheduling

• Activities
• Split project into tasks
• Estimate time resources required
• Organize tasks concurrently to make optimal use
  of workforce
• Minimize task dependencies to avoid delays

• Problems
• Estimating is difficult
• Productivity is not proportional to the number of
  people
• Adding people to a late project makes it later
• The unexpected always happens - allow contingency

16
Scheduling

• Derived from estimated level of effort required
• Build in mid-project checkpoints
• Dont forget testing integration take time too
• Be realistic
• Other classes
• Outside work/activities
• Eat sleep
• Build in safety nets backup plans

17
Project Plan

• Introduction
• Project organization
• Risk analysis
• Hardware and software resource requirements
• Work breakdown
• Milestones - end of process activity
• Deliverables - project results delivered to
  customer
• Project schedule
• Monitoring and reporting mechanisms

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18
In Summary...

• Good project management is essential for project
  success
• Managers have diverse roles, but focus on
• Planning
• Estimating
• Scheduling
• Planning and estimating are iterative processes

Sommerville, 1995