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process. For this reason, Abbott's heuristics are well suited to the initial stage of
the identification process, when candidate objects are determined.
Bruegge and Dutoit have created an additional set of heuristics to be used
together with Abbott's heuristics in determining each of the three analysis objects:
entity, boundary, and control objects. They suggest the following list be used in
identifying entity objects:
• Terms that must be clarified by developers or users to get a better understanding
of the use case.
• Nouns that show up multiple times.
• Real world entities that are to be tracked by the system.
• Real world activities that are to be tracked by the system.
• Data sources.
The following list they recommend for the identification of boundary objects:
• User interface controls that must be initiated by the user.
• Forms utilized by the user to pass data to the system.
• Responses the system presents to the user, such as notices, messages, and
warnings.
• NOT visual aspects of the interface.
Finally, they suggest the following list be used to in conjunction with Abbott's
heuristics to identify control objects:
• One control object per use case.
• One control object per actor in the use case.
• The lifespan of a control object should correspond with the lifespan of the use
case or user session being considered (Bruegge and Dutoit 2004 ).
6.6.2 Identifying Use Cases
The best way to find use cases is to consider what each actor requires of the
system. For each actor, human or not, ask:
• What are the goals that the actor will attempt to accomplish with the system?
• What are the primary tasks that the actor wants the system to perform?
• Will the actor create, store, change, remove, or read data in the system?
• Will the actor need to inform the system about sudden external changes?
• Does
the
actor
need
to
be
informed
about
certain
occurrences,
such
as
unavailability of a network resource, in the system?
• Will the actor perform a system startup or shutdown?
Understanding how the target organization works and how this information
system might be incorporated into existing operations gives an idea of a system's
surroundings. That information may reveal other use case candidates. Give a
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