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If the customer is not authorized to withdraw money from the account, the application notifies the teller. The application cancels the transaction. |
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If the teller, at the customer's request, tries to withdraw more money than is available, the application notifies the teller. The application cancels the transaction. |
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If the application discovers that the account has been frozen by the government, the application notifies the teller. The application cancels the transaction. |
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Notice the italicized sentences. These sentences represent reusable behavior. Hooray! You're midway through the development process and already you've identified some reusable artifacts. |
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The use-case model is the backbone of a project. All the artifacts in the object-oriented project are dependent on it in one way or another. Described another way, a use-case model is realized by the design model, meaning that solutions are represented in artifacts such as a class diagram, sequence diagram, collaboration diagram, state transition diagram, and activity diagram. The use-case model is eventually implemented in the implementation model, an example of which is your program code. Finally, the use-case model is verified against quality assurance constraints in the test model. The test model is represented by a master test plan, its test cases, and test scripts. You can even argue that a use-case model is important beyond the deployment of your application because it can be reused by business process designers and in other software development efforts. |
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Revisiting use cases helps to continually verify that the system is still on track to fulfill the requirements or user expectations of the Visual Basic application. This revisitation also helps to ensure that the use case model remains robust and easily extensible as discoveries are made about the problem and solution. Always keep in mind that the importance of updating the content of the use cases is that the use case model not only defines the application's behavior but also provides a basis for the development process of your project itself. |
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Although the use-case model must be understandable and acceptable to the users, it must also be a technically valid basis for the application in the eyes of the developers. Updating the use cases becomes important when gaps in business processes related to the application are discovered. |
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