Database Reference
In-Depth Information
details of each step. For example, an essential use case might doc-
ument that a rental car company employee “matches available cars
to a customer”; the corresponding real use case documents that
the employee “uses a third-party application to review available in-
ventory by model to determine the best available vehicle based on
the customer's request.”
Stakeholders
These are the individuals who have a tangible, immediate inter-
est in the process. In our example, a customer wants to reserve a
conference call, and a reservationist assists customers. In this
context, stakeholders are not those individuals who benefit from
the process in an ancillary way (such as the employees' manager).
This list always includes the principal.
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Description
The purpose of the process documented in the use case is to meet
the needs of the principal; the brief description is usually a single
statement that describes the process and how it meets that need.
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Trigger
The trigger is simply a statement describing what it is that sets
this process in motion.
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Type
A trigger can be an
external
trigger, meaning it is set in motion
by an external event, such a customer call. Or a trigger can be
temporal,
meaning it is enacted because of a timed event or be-
cause of the passage of time, such as an overdue movie rental.
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Relationships
The relationships explain how this use case is related to other use
cases, as well as users. There are three basic types of relationships
for use cases: include, extend, and generalization.
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Include
This relationship describes which other use cases must be exe-
cuted in order for this use case to complete. Using this relation-
ship, it is possible to break down complex systems into individual,
related use cases. After design begins, this relationship makes it
easy to break the workload into smaller pieces, enabling multiple
teams to work on a single system simultaneously.
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