Abstraction Difficulty in Use Cases

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I’m starting to study Use Cases and I came up with the following question:

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Difficulty of abstraction: I often confuse when creating several use cases but that in fact would only need one, because this would represent all. Are there any tips so that you can know what is and what is not a use case? In the example above, the use case "3. Make Payment" would be part of the use case "2. Place Order"? If part, the details regarding payment methods (use cases 4,5 and 6) should be in the use case specification "2. Place Order" demonstrating step-by-step?

Thank you very much!

uml use-cases
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    "In the example above, the use case "3. Make Payment" would be part of the use case "2. Place Order"?" Raphael, I believe so, since it would always be necessary to place an order before paying it off.

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There are some tips to know what is and what is not a use case?

Use case is used to identify and record the functional requirements of the system. Use Case Diagrams help communication between analysts and the system, describing the scenario with functionalities.

The Use Case diagram is represented by:

  • actors;
  • use cases;
  • relationships between these elements.

These relationships can be:

  • associations between actors and use cases;
  • generalizations among actors;
  • generalizations, extends and includes among cases of use.


In the above example, the use case "3. Make Payment" would be part of the use case "2. Place Order"?

In your diagram, 3 is part of 2. That’s right include. That’s what he’s for.

To understand better, in UFCG website has that explanation:

  • Include: A relationship include of a use case A for a use case B indicates that B is essential for the behavior of A. It can also be said that B is_part_of A.

  • Extend: A relationship extend of a use case B for a use case A indicates that use case B can be added to describe the behavior of A (not essential). The extension is inserted at an extension point of the use case A. Extension point in a use case is an indication that other use cases may be added to it. When the use case is invoked, it verify whether or not your extensions should be invoked. When specifies B extends A, the semantics is:

    • Two use cases are defined: A and A Extended by B;
    • B is a variation of A. Contains additional events for certain conditions;
    • It has to be specified where B is inserted in A.

Usefulness of the use case

Although simple they are useful from communicating with the customer to generating test cases. This is because they do not require technical knowledge and the customer can understand the diagram effortlessly. In addition, new use cases generate new requirements and the merging of all scenarios are used to suggest the tests for each scenario.

References:

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