Case

Use Cases

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Version 1.0 approved


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Guidance for Use Case Template

Document each use case using the template shown in the Appendix. This section provides a description of each section in the use case template.


Use Case Identification


1 Use Case ID

Give eachuse case a unique integer sequence number identifier. Alternatively, use a hierarchical form: X.Y. Related use cases can be grouped in the hierarchy.


2 Use Case Name

State a concise, results-oriented name for the use case. These reflect the tasks the user needs to be able to accomplish using the system. Include an action verb and a noun. Some examples:

View part number information.Manually mark hypertext source and establish link to target.
Place an order for a CD with the updated software version.

3 Use Case History


1 Created By

Supply the name of the person who initially documented this use case.


2 Date Created

Enter the date on which the use case was initially documented.


3 Last Updated By

Supply the name of the person who performed the mostrecent update to the use case description.


4 Date Last Updated

Enter the date on which the use case was most recently updated.


Use Case Definition


1 Actors

An actor is a person or other entity external to the software system being specified who interacts with the system and performs use cases to accomplish tasks. Different actors often correspond to different user classes, orroles, identified from the customer community that will use the product. Name the actor that will be initiating this use case and any other actors who will participate in completing the use case.


2 Trigger

Identify the event that initiates the use case. This could be an external business event or system event that causes the use case to begin, or it could be the first step in the normalflow.


3 Description

Provide a brief description of the reason for and outcome of this use case, or a high-level description of the sequence of actions and the outcome of executing the use case.


4 Preconditions

List any activities that must take place, or any conditions that must be true, before the use case can be started. Number each precondition. Examples:

1. User’s identityhas been authenticated.
2. User’s computer has sufficient free memory available to launch task.

5 Postconditions

Describe the state of the system at the conclusion of the use case execution. Number each postcondition. Examples:

1. Document contains only valid SGML tags.
2. Price of item in database has been updated with new value.

6 Normal Flow

Provide a detaileddescription of the user actions and system responses that will take place during execution of the use case under normal, expected conditions. This dialog sequence will ultimately lead to accomplishing the goal stated in the use case name and description. This description may be written as an answer to the hypothetical question, “How do I ?” This is best done as a numbered list of actions performedby the actor, alternating with responses provided by the system. The normal flow is numbered “X.0”, where “X” is the Use Case ID.


7 Alternative Flows

Document other, legitimate usage scenarios that can take place within this use case separately in this section. State the alternative flow, and describe any differences in the sequence of steps that take place. Number each alternative flow...