Applied Software Project Management

Use Cases

Once the initial round of requirements elicitation is done and a discussion summary has been distributed and reviewed, the requirements analyst is ready to begin creating use cases . A use case is a description of a specific interaction that a user may have with the software. Use cases are deceptively simple tools for describing the behavior of the software.

A use case contains a textual description of all of the ways that the intended users could work with the software through its interface. Use cases do not describe any internal workings of the software, nor do they explain how that software will be implemented. They simply show the steps that the user follows to use the software to do his work. All of the ways that the users interact with the software can be described in this manner.

A typical use case includes these sections, usually laid out in a table. Table 6-2 shows a template for describing a use case.

Table 6-2. Use case template

Name	Use case number and name
Summary	Brief description of the use case
Rationale	Description of the reason that the use case is needed
Users	A list of all of the categories of users that interact with this use case
Preconditions	The state of the software before the use case begins
Basic Course of Events	A numbered list of interactions between the user and one or more users
Alternative Paths	Conditions under which the basic course of events could change
Postconditions	The state of the software after the basic course of ...