Sample chapter: Developing Requirements for Enhancement and Replacement Projects

This chapter from Software Requirements, 3rd Edition provides specific suggestions as to which practices are most relevant for enhancement and replacement projects and how to use them.

Most of this book describes requirements development as though you are beginning a new software or system development project, sometimes called a green-field project. However, many organizations devote much of their effort to enhancing or replacing existing information systems or building new releases of established commercial products. Most of the practices described in this book are appropriate for enhancement and replacement projects. This chapter provides specific suggestions as to which practices are most relevant and how to use them.

An enhancement project is one in which new capabilities are added to an existing system. Enhancement projects might also involve correcting defects, adding new reports, and modifying functionality to comply with revised business rules or needs.

A replacement (or reengineering) project replaces an existing application with a new custom-built system, a commercial off-the-shelf (COTS) system, or a hybrid of those. Replacement projects are most commonly implemented to improve performance, cut costs (such as maintenance costs or license fees), take advantage of modern technologies, or meet regulatory requirements. If your replacement project will involve a COTS solution, the guidance presented in Chapter 22 will also be helpful.

Replacement and enhancement projects face some particular requirements issues. The original developers who held all the critical information in their heads might be long gone. It’s tempting to claim that a small enhancement doesn’t warrant writing any requirements. Developers might believe that they don’t need detailed requirements if they are replacing an existing system’s functionality. The approaches described in this chapter can help you to deal with the challenges of enhancing or replacing an existing system to improve its ability to meet the organization’s current business needs.

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