1. Iteration 3 Relating Use Cases Domain Model Refinement SSD and Contracts

2. Relating Use Case

3. Avoid agonizing over use cases Use cases can be related, have common subtasks While useful - this can waste time! “Analysis paralysis” Write the use cases first Find obvious relations as you go, when they make sense and help Don’t agonize over getting it perfect. “A good plan now is worth a perfect plan in the indefinite future.” - George Patton

4. Use Case Terminology Concrete - performs an entire action Abstract - use cases that cannot standalone - part of another use case Base - Use cases that include other use cases

5. Include Allows dividing use cases into sub use cases Can decompose a complex use case Asynchronous events Under extensions * mark async actions Use include to separate out details Include is a “pointer” from the original use case to something new.

6. Extend For baselined use cases Used when the initial use cases cannot be changed. Inherited from another project Not worth going back to update and change Baselined Documents an earlier version Does not have a pointer from the original use case.

7. Fig. 30.1 Process Sale and the new Process Rental are updated to include the various payment types.

8. Fig. 30.2 Process Sale does not have a “gift certificate” state.

9. Summary Tweaks on use cases Why are we coming back to use cases? When you learn a new process, you have to jump in somewhere along the cycle. Not clear what to do until you have a view of the entire cycle. Once the overall structure is in place, come back and fill in some of the details