The following are the definitions of the key concepts of Use-Case −
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, or roles, identified from the customer community that will use the product. Name the actor(s) that will be performing this usecase.
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.
List any activities that must take place, or any conditions that must be true, before the use-case can be started. Number each precondition.
● User’s identity has been authenticated.
● User’s computer has sufficient free memory available to launch task.
Describe the state of the system at the conclusion of the use-case execution. Number each post condition.
● Document contains only valid SGML tags.
● Price of item in database has been updated with new value.
Indicate the relative priority of implementing the functionality required to allow this usecase to be executed. The priority scheme used must be the same as that used in the software requirements specification.
Frequency of Use
Estimate the number of times this use-case will be performed by the actors per some appropriate unit of time.
Normal Course of Events
Provide a detailed description 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 <accomplish the task stated in the use-case name>?” This is best done as a numbered list of actions performed by the actor, alternating with responses provided by the system.
Document other, legitimate usage scenarios that can take place within this use-case separately in this section. State the alternative course, and describe any differences in the sequence of steps that take place. Number each alternative course using the Use-case ID as a prefix, followed by “AC” to indicate “Alternative Course”. Example: X.Y.AC.1.
Describe any anticipated error conditions that could occur during execution of the usecase, and define how the system is to respond to those conditions. Also, describe how the system is to respond if the use-case execution fails for some unanticipated reason. Number each exception using the Use-case ID as a prefix, followed by “EX” to indicate “Exception”. Example: X.Y.EX.1.
List any other use-cases that are included (“called”) by this use-case. Common functionality that appears in multiple use-cases can be split out into a separate use-case that is included by the ones that need that common functionality.
Identify any additional requirements, such as nonfunctional requirements, for the usecase that may need to be addressed during design or implementation. These may include performance requirements or other quality attributes.
List any assumptions that were made in the analysis that led to accepting this use-case into the product description and writing the use-case description.
Notes and Issues
List any additional comments about this use-case or any remaining open issues or TBDs (To Be Determined) that must be resolved. Identify who will resolve each issue, the due date, and what the resolution ultimately is.
Change Management and Version control
Version control is the management of changes to documents, large websites, and other collection of information. Changes are usually identified by a number or letter code, termed as revision number or revision level. Each revision is associated with a timestamp and person making the change.