When the user-goal level use cases are identified (in most cases from modeling elementary business processes), we model a use case diagram per user-goal level use case.
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To identify sub-function level use cases that participate in realizing a particular user-goal level use cases, a number of guidelines apply:
- Identify re-use. Quite often sub-function level use cases can be reused by other user-goal or sub-function level use cases.
- One form per use cases. Do not model more than one form per use case. This would require to describe all interaction
- Model one use case per functional web part
- Isolate unknown functionality
- Identify complex functionality
- Show extensive reporting
- Model complex calculations
- Isolate interaction with others
- Avoid low level (database) interaction