Software requirements gathering techniques

TABLE OF CONTENTS    Prototyping    Storyboards    Modeling    State transition diagrams    Use cases    Tools    Other Useful Resources

Prototyping

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Prototypes range from the simple to the elaborate. But whether it's a paper sketch or an interactive digital design, a prototype should aid stakeholders and developers in anticipating requirements for a product.

• Effective Prototyping for Software Makers -- Chapter 2, The Effective Prototyping Process: Prototyping is a process anyone can learn and master, according to author Jonathan Arnowitz. In this book excerpt, he describes the four phases of the prototyping process -- plan, specification, design and results -- and how you can use prototyping to communicate software requirements, designs and ideas.
• Create screen prototypes for clear software requirements: A step by step approach to communicating with your customers and getting the most out of your prototypes.
• Evaluating 'throw away' prototyping for requirements capture: A dense white paper filled with examples and graphics. (PDF)
• What is prototyping: This outline answers basic questions about prototyping and offers advice for creating effective GUI prototypes.
• Prototyping: The sheer amount of information on all things prototyping may be overwhelming for some, but it's presented clearly and concisely on this bare bones site.
• Extending the benefits of prototyping: Great advice for those experienced in prototyping who have demanding customers, or who simply need a few new ideas.
• Prototyping and the software development cycle: The article may be old (the information is largely from 1992) but for those approaching prototyping for the first time, or for those who need a refresher, the combination of elemental information and good writing is hard to beat.
• Using paper prototypes to manage risk: Using a real-life scenario, the authors explain why and how paper prototypes can be ideal for risk management in a time crunch.
• Looking back on 16 years of paper prototyping: With all of the changes and advancements over the past 16 years, the authors explain why paper prototypes are relevant and beneficial in technology today.

Storyboards

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Storyboards help developers visualize the sequence and interconnectedness of their work. They allow for a "big picture" approach that may be very useful in requirements gathering.

• Form feeds function -- The role of storyboards in requirements elicitation: Simply put, the author details how storyboards aid in communication with end users and the establishment of requirements.
• Storyboarding for design -- An overview of the process: Storyboards can be quite effective, but they must be well-designed to reach their full potential. This white paper offers 11 steps for creating productive storyboards. (PDF)
• The storyboard's big picture: One NASA team's account of how storyboarding improved their development process. Hey, if it's good enough for NASA ...
• Storyboarding -- Building effective dashboards: Using a real-life example, this article offers tips for quality storyboarding.
• Creating the storyboard: This is simply a worksheet for using storyboards to craft Web courses. However, the worksheets are a simple introduction to storyboards and should benefit beginners.
• User Interface flow diagrams (storyboards): The agile answer to storyboards.
• Use cases and stories: An explanation of the differences between use cases and the stories of Extreme Programming (XP).

Modeling

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A model can be made according to Unified Modeling Language (UML) or according to domain-specific modeling. Or, models can consist of stick figures on a whiteboard. All of these methods have their advantages and disadvantages. Use these links to figure out what method is right for you.

• The value of modeling: This white paper is an introduction to modeling, why it should be employed and the very basics of beginning software modeling. (PDF)
• UML for the software developer, Part 1 -- Building classes: Concentrating on three UML model diagram types, the author demonstrate how UML classes relate to code. There are diagrams and code examples to aid the reader.
• UML for the software developer, Part 2 -- Mastering associations: The second part of this series explains how developers can understand the relationships among classes in UML.
• Domain-specific modeling -- Welcome to the next generation of software modeling: The author lays out the shortcomings of UML and argues for DSM. By increasing abstraction, he argues, we reduce complexity.



• Modeling in the agile methodology
  
  While these links discuss modeling from an agile software development perspective, the lessons may still be valuable to those practicing other methodologies. At the very least, one can gather ideas for one's own modeling processes.
  
  
  • Agile requirements modeling example: A detailed outline of requirements modeling from an agile standpoint.
  • Software modeling on plain old whiteboards (POWs): The benefits of whiteboards may appeal to developers across the board. This article describes how to take good photos of whiteboards to preserve the information for when it is inevitably wiped off.
  • Comparing the various approaches to modeling in software development: This is a clear, succinct overview of modeling approaches, paradigms and estimated adoption rates. A handy graph lays it all out.
  • Simple tools for software modeling: Post-Its, index cards and whiteboards are extolled in this article, but CASE tools are discussed as well. The author lays out the benefits (and disadvantages) of CASE and offers suggestions for selecting CASE tools.

State transition diagrams

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State transition diagrams allow developers and users to see how a program might behave. This anticipation of events is useful when discussing requirements.

• State-transition diagrams: This article explains what state transitions are and why they are important. Also included are a series of questions for testing state-transition diagrams.
• UML tutorial -- State diagrams: This is simply a very short guide to drawing state diagrams.
• Automating state transitions: The Microsoft Developer's Network state transitions within Visual Studio. Code examples aid the reader.
• Visual Requirements: There is a section devoted to state transition diagrams in this article on diagrams in software development. The author provides a clear perspective on state diagrams and the necessary part they play among the other diagrams. (PDF)
• State transition diagrams: The language of this white paper is technical, so beginners may be put off. However, the paper achieves what it sets out to do, and that is to define the syntax and semantics of state transition diagrams. (PDF)

Use cases

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Use cases are created to capture functional requirements in the software development lifecycle.

• Software requirements analysis: Five use case traps to avoid: Employing use cases during software requirements analysis helps you improve your chances of developing software that truly meets their needs. But there are traps you should avoid, says expert Karl E. Wiegers, Ph.D.
• Planning requirements for multiple software product releases: Most software products evolve over time. The challenge is creating a release strategy that provides the maximum customer value consistent with budgets, schedules, resources and business objectives. This article written by Karl E. Wiegers describes two techniques for planning such release strategies.
• Use-Case Model -- Writing Requirements in Context: A well-written use case is an excellent tool in the requirements gathering process. This chapter is a great primer on creating use cases. (PDF)
• Listening to the customer's voice: Understanding the customer's needs is crucial in requirements gathering. This article explains how use cases can facilitate communication with users.
• Functional requirements and use cases: The connection between functional requirements and use cases is clarified in this white paper. A use case template and diagram are very helpful visual resources, the template in particular. (PDF)
• Process perspective -- There is more to requirements than just use cases and UML: This article discusses the limitations of use cases (and UML) and what can be used to supplement use cases during requirements gathering.

Tools

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Here are some tools that may prove useful in the requirements gathering process.

• Agile requirements gathering with user stories: ExtremePlanner is designed to help agile developers organize user stories.
• Automated Requirement Measurement (ARM) tool: This is a writing aid from the Software Assurance Technology Center at NASA.
• Requirements management for software engineering: Borland's DefineIT and CaliberRM are well-known requirements tools.
• stpsoft requirements storyboarding for Visual Studio: A storyboarding product designed for the VS Team System.
• Rapid Prototyping and Application Development Contains a list of requirements and project management tools. (A couple of the links are expired.)
• My Little UML (Tools) Page An excellent Web site for UML tools. There are long lists - complete with descriptions - of open-source and commercial tools the author has had experience with and a list of commercial tools the author hasn't used. In addition, there's a little list of UML tools that are defunct for those who aren't quite up to date.

Other useful resources

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Expert advice on software requirements Do you have a question about software requirements gathering? Our requirements expert Karl Wiegers may have the answer. Read advice he has given or submit your own questions.

• Ambiguous software requirements lead to confusion, extra work: Ambiguous requirements lead to confusion, wasted effort and rework. This article from software requirements expert Karl E. Wiegers, Ph.D. describes several common types of requirements ambiguity and suggests how to avoid them.
• Software Requirements, Second Edition -- Chapter 7, Hearing the Voice of the Customer: The heart of requirements engineering is elicitation, the process of identifying the needs and constraints of the various stakeholders for a software system. In this book excerpt Karl Wiegers, Ph.D. addresses the general principles of effective requirements elicitation.
• User Requirements for Software Development: This is a four-day course on requirements gathering.
• Requirements Engineering Journal: Yes, there is a journal devoted entirely to requirements.
• Writing Effective Use Cases: Alistair Cockburn advises readers how to write -- as opposed to model -- use cases in this book.
• Managing Software Requirements: A Unified Approach: Dean Leffingwell and Don Widrig emphasize team skills in this book.

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