Managing Software Requirements

Dean Leffingwell, software business development consultant and former Rational Software executive, is a recognized authority on software requirements. He was cofounder and chief executive officer of Requisite, Inc., where he developed RequisitePro, the highly successful requirements management software tool, and Requirements College, the basis of Rational's popular requirements management professional development course series. Don Widrig is an independent technical writer and consultant. He developed and delivered Rational Software's RequisitePro Tool Training Course until his "retirement" to the mountains of Colorado in 1997. When he is not busy watching the elk in his yard, Don writes a regular column for his local newspaper and does pro bono work helping the townspeople deal with their computers. He was formerly the vice president of research and development at RELA, Inc., a producer of safety-critical, real-time systems. 032112247XAB05082003

Foreword.


Preface to the Second Edition.


Preface to the First Edition.


Introduction.


1. The Requirements Problem.


The Goal of Software Development.



A Look at the Data.



The Root Causes of Project Success and Failure.



The Frequency of Requirements Errors.



The High Cost of Requirements Errors.



Summary.



2. Introduction to Requirements Management.


Definitions.



What Is a Software Requirement?



What Is Requirements Management?



Application of Requirements Management Techniques.



Types of Software Applications.



Systems Applications.



The Road Map.



The Problem Domain.



Stakeholder Needs.



Moving Toward the Solution Domain.



Features of the System.



Software Requirements.



Summary.



3. Requirements and the Software Lifecycle.


Traditional Software Process Models.



The Waterfall Model.



The Spiral Model.



The Iterative Approach.



Lifecycle Phases.



Iterations.



Disciplines.



Requirements in the Iterative Model.



Summary.



4. The Software Team.


Software Development as a Team Activity.



Requisite Team Skills for Effective Requirements Management.



Team Members Have Different Skills.



The Organization of Software Teams.



The Case Study.



Background for the Case Study.



The HOLIS Software Development Team.



Summary.



Team Skill 1 Analyzing the Problem.



5. The Five Steps in Problem Analysis.


Step 1: Gain Agreement on the Problem Definition.



The Problem Statement.



Step 2: Understand the Root Causes-The Problem Behind the Problem.



Addressing the Root Cause 48



Step 3: Identify the Stakeholders and the Users.



Step 4: Define the Solution System Boundary.



Step 5: Identify the Constraints to Be Imposed on the Solution.



Summary.



Looking Ahead.



6. Business Modeling.


The Purpose of Business Modeling.



Using Software Engineering Techniques for Business Modeling.



Choosing the Right Technique.



The Unified Modeling Language.



Business Modeling Using UML Concepts.



From the Business Model to the Systems Model.



When to Use Business Modeling.



Summary.



Looking Ahead.



7. Systems Engineering of Software-Intensive Systems.


What Is Systems Engineering?



Pragmatic Principles of Systems Engineering.



The Composition and Decomposition of Complex Systems.



Requirements Allocation in Systems Engineering.



On Derived Requirements.



A Quiet Revolution.



When Generations Collide: Graying Baby Boomer Meets Generation X-er.



Avoiding the Stovepipe System Problem.



When Subsystems Are Subcontracts.



Addressing the Conundrum.



The Case Study: Systems Engineering for HOLIS.



Preliminary User Needs.



Problem Analysis.



HOLIS: The System, Actors, and Stakeholders.



HOLIS Systems Engineering.



The Subsystems of HOLIS.



Summary.



Team Skill 1 Summary.



Team Skill 2 Understanding User and Stakeholder Needs.



8. The Challenge of Requirements Elicitation.


Barriers to Elicitation.



The "Yes, But" Syndrome.



The "Undiscovered Ruins" Syndrome.



The "User and the Developer" Syndrome.



Summary.



9. The Features of a Product or System.


Stakeholder and User Needs.



Features.



Managing Complexity by Picking the Level of Abstraction.



Attributes of Product Features.



Summary.



10. Interviewing.


Context-Free Questions.



Solutions-Context Questions.



The Moment of Truth: The Interview.



Compiling the Needs Data.



The Analyst's Summary: 10 + 10 + 10 pi 30.



The Case Study.



A Note on Questionnaires.



Summary.



11. Requirements Workshops.


Accelerating the Decision Process.



Preparing for the Workshop.



Selling the Concept.



Ensuring the Participation of the Right Stakeholders.



Attending to Logistics.



Providing Warm-Up Materials.



Choosing the Facilitator.



Setting the Agenda.



Running the Workshop.



Problems and Tricks of the Trade.



Brainstorming and Idea Reduction.



Production and Follow-Up.



Summary.



12. Brainstorming and Idea Reduction.


Live Brainstorming.



Idea Reduction.



Pruning Ideas.



Grouping Ideas.



Defining Features.



Prioritizing Ideas.



Web-Based Brainstorming.



The Case Study: The HOLIS Requirements Workshop.



The Attendees.



The Workshop.



The Session.



The Analysis of Results.



Summary.



13. Storyboarding.


Types of Storyboards.



What Storyboards Do.



Tools for Storyboarding.



Tips for Storyboarding.



Summary.



Team Skill 2 Summary.



Team Skill 3 Defining the System.



14. A Use Case Primer.


The Benefits of Use Cases.



Use Case Basics.



On Actors.



Use Case Anatomy.



A Step-by-Step Guide to Building the Use-Case Model.



Step 1: Identify and Describe the Actors.



Step 2: Identify the Use Cases and Write a Brief Description.



Step 3: Identify the Actor and Use-Case Relationships.



Step 4: Outline the Individual Use Cases.



Step 5: Refine the Use Cases.



On Use Cases, Storyboarding, and User Interface Design.



Use Cases and User Interfaces.



Use Cases and Storyboarding.



A Use Case Storyboard Example.



The Case Study: The HOLIS Use Cases.



Find the HOLIS Actors.



Find the HOLIS Use Cases.



Associate the Actors and Use Cases.



Outline the Use Cases.



Summary.



15. Organizing Requirements Information.


Organizing Requirements of Complex Hardware and Software Systems.



Organizing Requirements for Product Families.



On "Future" Requirements.



The Case Study: Organizing the HOLIS Requirements.



Summary.



Looking Ahead.



16. The Vision Document.


Components of the Vision Document.



The Delta Vision Document.



The Vision Document for Version 1.0.



The Vision Document for Version 2.0.



The Delta Vision Document in a Legacy System Environment.



Summary.



17. Product Management.


The Role of the Product Champion.



The Product Manager in a Software Product Company.



Primary Activities for a Product Manager.



Driving the Vision.



Maintaining the Product Road Map.



Defining the Whole Product Plan.



Sponsoring the Use-Case Model and Supplementary Requirements.



Testing the Product Concept.



Completing the User Experience.



Defining Commercial Terms.



Positioning and Messaging.



Supporting Activities.



Branding and Product Labeling.



End User Training Materials.



Product Demo.



Sales and Marketing Collateral.



The Product Champion in an IS/IT Shop.



Summary.



Team Skill 3 Summary.



Team Skill 4 Managing Scope.



18. Establishing Project Scope.


The Problem of Project Scope.



The Hard Question.



The Requirements Baseline.



Setting Priorities.



Assessing Effort.



Adding the Risk Element.



Reducing Scope.



A Reasonable First Estimate.



The Case Study: Scope Management for HOLIS.



Summary.



19. Managing Your Customer.


Engaging Customers to Manage Their Project Scope.



Communicating the Result.



Negotiating with the Customer.



Managing the Baseline.



Official Changes.



Unofficial Changes.



Summary.



Team Skill 4 Summary.



Team Skill 5 Refining the System Definition.



20. Software Requirements-A More Rigorous Look.


Looking Deeper into Software Requirements.



The Relationship between Software Requirements and Use Cases.



The Relationship between Features and Software Requirements.



The Requirements Dilemma: What versus How.



Excluding Project Information.



Excluding Design Information.



More on Requirements versus Design.



Iterating Requirements and Design.



A Further Characterization of Requirements.



Functional Software Requirements.



Nonfunctional Software Requirements.



Design Constraints.



Summary.



Looking Ahead.



21. Refining the Use Cases.


How Use Cases Evolve.



The Scope of a Use Case.



The Case Study: Anatomy of a Simple Use Case.



Reviewing the Actors.



Reviewing the Name.



Refining the Description.



Defining and Refining the Flow of Events.



Identifying the Pre- and Post-conditions.



Identifying Special Requirements.



Summary of Our Refined Use Case.



Extending Use Cases.



Including Use Cases in Other Use Cases.



Summary.



Looking Ahead.



22. Developing the Supplementary Specification.


The Role of the Supplementary Specification.



Expressing Functional Requirements in the Supplementary Specification.



Exploring Nonfunctional Requirements.



Usability.



Reliability.



Performance.



Supportability.



Understanding Design Constraints.



Sources of Design Constraints.



Handling Design Constraints.



Are Design Constraints True Requirements?



Identifying Other Requirements.



Linking the Supplementary Specification to the Use Cases.



Template for the Supplementary Specification.



Summary.



Looking Ahead.



23. On Ambiguity and Specificity.


Finding the "Sweet Spot".



Mary Had a Little Lamb.



Techniques for Disambiguation.



Summary.



24. Technical Methods for Specifying Requirements.


Pseudocode.



Finite State Machines.



Decision Tables and Decision Trees.



Activity Diagrams.



Entity-Relationship Models.



Summary.



Team Skill 5 Summary.



Team Skill 6 Building the Right System.



25. From Use Cases to Implementation.


Mapping Requirements Directly to Design and Code.



The Orthogonality Problem.



Object Orientation.



The Use Case as a Requirement.



Managing the Transition.



Modeling Software Systems.



The Architecture of Software Systems.



The Role of the Use-Case Model in Architecture.



Realizing Use Cases in the Design Model.



Structural and Behavioral Aspects of Collaborations.



Using Collaborations to Realize Sets of Individual Requirements.



From Design to Implementation.



Summary.



Looking Ahead.



26. From Use Cases to Test Cases.


A Tester's Perspective: Musings on the Big Black Box.



Is a Use Case a Test Case?



Common Testing Terms.



Relationships of Test Artifacts.



The Role of the Test Cases.



Use-Case Scenarios.



Deriving Test Cases from Use Cases: A Four-Step Process.



Step 1: Identify the Use-Case Scenarios.



Step 2: Identify the Test Cases.



Step 3: Identify the Test Conditions.



Step 4: Add Data Values to Complete the Test Case.



Managing Test Coverage.



Black-Box versus White-Box Testing with Use Cases.



Summary.



27. Tracing Requirements.


The Role of Traceability in Systems Development.



The Traceability Relationship.



A Generalized Traceability Model.



Tracing Requirements in the System Definition Domain.



Tracing Requirements to Implementation.



Tracing from Requirements to Testing.



Using Traceability Tools.



Proceeding without Traceability Tools.



Summary.



28. Managing Change.


Why Do Requirements Change?



External Factors.



Internal Factors.



°We Have Met the Enemy, and They Is Us°.



A Process for Managing Change.



Step 1: Recognize That Change Is Inevitable, and Plan for It.



Step 2: Baseline the Requirements.



Step 3: Establish a Single Channel to Control Change.



Step 4: Use a Change Control System to Capture Changes.



Step 5: Manage Change Hierarchically.



Requirements Configuration Management.



Tool-Based Support for Change Management.



Elements Impacted by Change.



Audit Trail of Change History.



Configuration Management and Change Management.



Summary.



Looking Ahead.



29. Assessing Requirements Quality in Iterative Development.


Software Project Quality.



Assessing Quality in Iterative Development.



Requirements Artifacts Sets.



Performing the Assessment.



Quality Assessment Checklists for Requirements.



Summary.



Team Skill 6 Summary.



Looking Ahead.



Getting Started.



Dedication.



What You've Learned So Far.



Introduction.



Team Skill 1: Analyzing the Problem.



Team Skill 2: Understanding User and Stakeholder Needs.



Team Skill 3: Defining the System.



Team Skill 4: Managing Scope.



Team Skill 5: Refining the System Definition.



Team Skill 6: Building the Right System.



30. Agile Requirements Methods.


Mitigating Requirements Risk with Effective Requirements Practices.



Methodology Design Goals.



Documentation Is a Means to an End.



An Extreme Requirements Method.



An Agile Requirements Method.



A Robust Requirements Method.



Summary.



31. Your Prescription for Requirements Management.


Selecting Your Requirements Approach.



The Simplifying Assumptions.



The Prescription.



On to the Next Release!



Appendixes.


Appendix A. HOLIS Artifacts.


Appendix B. Vision Document Template.


Appendix C. Use-Case Specification Template.


Appendix D. Supplementary Specification Template.


Appendix E. Requirements Management in the Rational Unified Process.


Appendix F. Requirements Management in the SEI-CMM and within ISO 9000:2000.


Bibliography.


Index. 032112247XT05082003