6.19. Motivation: Other Benefits of Use Cases? Requirements in Context
A motivation for use cases is focusing on who the key actors are, their goals, and common tasks. Plus, in essence, use cases are a simple, widely-understood form (a story or scenario form).motivation p. 64 Another motivation is to replace detailed, low-level function lists (which were common in 1970s traditional requirements methods) with use cases. These lists tended to look as follows:
ID | Feature |
---|---|
FEAT1.9 | The system shall accept entry of item identifiers. |
… | … |
FEAT2.4 | The system shall log credit payments to the accounts receivable system. |
High-Level System Feature Lists Are Acceptable
Vision p. 109 Although detailed function lists are undesirable, a terse, high-level feature list, called system features, added to a Vision document can usefully summarize system functionality. In contrast to 50 pages of low-level features, a system features list includes only a few dozen items. It provides a succinct summary of functionality, independent of the use case view. For example:
Summary of System Features
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When Are Detailed Feature Lists Appropriate Rather than Use Cases?
Sometimes use cases do not really fit; some applications cry out for a feature-driven viewpoint. For example, application servers, database products, and other middleware or back-end systems need to be primarily considered and evolved in terms of features ("We need Web Services support in the next release"). Use cases are not a natural fit for these applications or the way they need to evolve in terms of market forces.