Understanding and Creating Use Cases in Systems Analysis and Design

Any readings from the course textbook can be found under the Digital Book area of the course.

In the textbook, Systems Analysis and Design, Fifth Edition, read the following:

• Chapter 4: “Use Case Analysis”

Please also review Chapter 1.

Summary

Use cases were used to explain and document the interaction that is required between the user and the system to accomplish the user’s task. Use cases are created to help the development team understand more fully the steps that are involved in accomplishing the user’s goals. Once created, use cases often can be used to derive more detailed functional requirements for the new system.

A use case contains all the information needed to build one part of a process model, expressed in an informal, simple way. A use case has a name, number, importance level, brief description, primary actor, trigger(s), preconditions, postconditions, major inputs and outputs, and a list of the major steps required to perform it. Use cases can be identified by reviewing the functional requirements. An event-response list also is useful in identifying the significant events that should be described in a use case. Once the use case is completed, often new and expanded functional requirements can be derived.

Creating Use Cases

When writing a use case, first identify the triggering event (external or temporal) and the primary actor. Next, develop a list of the major steps involved in using the input(s) to produce the needed output(s) and desired response(s) to the event. Now, think more deeply about each step and identify the specific input(s) and output(s) for every step. Finally, have the users role-play the use case to verify that it is correct as written.

In the textbook, Systems Analysis and Design, Fifth Edition, the following table describes Steps for Writing for Use Cases:

FIGURE 4-5 Steps for Writing for Use Cases