Mastering the Requirements Process
- The Requirements Process in Context
- A Case Study
- Project Blastoff
- Trawling for Requirements
- Quick and Dirty Modeling
- Writing the Requirements
- Quality Gateway
- Reusing Requirements
- Reviewing the Requirements
- Iterative and Incremental Processes
- Requirements Retrospective
- Evolution of Requirements
- The Template
- The Snow Card
- Your Own Requirements Process
- Formality Guide
- The Rest of This Book
This book is a distillation of our experience. In it, we describe a requirements process that we have derived from our years of working in the requirements arena—working with clever people who do clever things, and working on projects in wonderfully diverse domains. We have also learned much from the experience of the many people around the world who use various parts of our techniques.
We developed the Volere Requirements Process and its associated specification template from the activities and deliverables that had proved themselves to be most effective in project and consulting assignments with our clients. The result of this experience is a requirements discovery and specification process whose principles can be applied—and indeed have been applied—to almost all kinds of application types in almost all kinds of development environments.
We want to stress from the very beginning that while we are presenting a process, we are using it as a vehicle for discovering requirements; we do not expect you to wave this process around and tell your co-workers that it is “the only way to do things.” However, we have high expectations that you will find many useful things from this process that will, in turn, help you to discover and communicate your requirements more productively and accurately. We have personally seen hundreds of companies adapt the process to their own cultures and organizations, and we know of thousands more that have done so.
Our clients who use the Volere Requirements Process are those who develop their products using RUP, incremental, iterative, spiral, Scrum, or other variations of iterative development; more formalized waterfall processes; and a variety of homebrewed development processes. Over the years, all of these clients agreed with us: If the right product is to be built, the right requirements have to be discovered. But requirements don’t come about by fortuitous accident. To find the correct and complete requirements, you need some kind of orderly process.
The Volere Requirements Process is shown in Figure 2.1. Each of the activities included in the figure, along with the connections between them, is described in detail in subsequent chapters of this book.
Figure 2.1. This map of the Volere Requirements Process shows the activities and their deliverables. We have used a stylized data flow notation. Each activity (the bubbles) and its deliverables (named arrows or documents) are explained in the text. The dotted lines represent how this process is used with iterative projects.
The Requirements Process in Context
We need to point out—indeed, we need to stress—that this process is not intended to be a waterfall approach. At various stages throughout this book, we will point out how you might modify the process if you are using some kind of iterative development.
Requirements discovery should be seen as a necessary forerunner of any construction activity, but it should also be viewed as something that can be conducted quite quickly, sometimes quite informally, sometimes overlapping with subsequent design and construction activities, but never ignored.
Let’s look briefly at each of the activities shown in Figure 2.1, which are covered in more detail in subsequent chapters. The intention of this chapter is to give you a gentle introduction to the process, its components, its deliverables, and the ways that they fit together. If you want more detail on any of the activities, feel free to jump ahead to the relevant chapter before completing this overview.
As we go through the process, we describe it as if you were working with a brand-new product—that is, developing something from scratch. We take this approach to avoid, for the moment, becoming entangled in the constraints that are part of all maintenance projects. Later, we will discuss requirements for those situations when the product already exists and changes to it are required.
- “The likelihood of frost or ice forming is determined by the energy receipt and loss at the road surface. This energy flow is controlled by a number of environmental and meteorological factors (such as exposure, altitude, road construction, traffic, cloud cover, and wind speed). These factors cause significant variation in road surface temperature from time to time and from one location to another. Winter night-time road surface temperatures can vary by over 10°C across a road network in a county.”
- —Vaisala News