Divide energy of writing use cases into 4 stages of precision, according to the amount of energy required and the value of pausing after each stage.
- Actors and Goals: List the actors and their goals system will support. Review the list for accuracy and completeness. prioritize and assign Goals to the teams and release. This gives us functional requirement and the first level of precision.
- Use case brief or the Main Success story: For the use case we selected in previous step, sketch the main success story. Review them in draft form to ensure it delivers the interest of stakeholders we care about.
- Failure condition: Brainstorm all failure scenario. LIST THIS COMPLETELY BEFORE MOVING TO HOW THE SYSTEM WILL HANDLE THEM. as handling the failure requires more energy, we tend to loose energy if we move to handling them before listing all possible scenario.
- Failure handling: Write how the system is supposed to handle each failure. This step and exhausting and tricky. This often reveal a new actor or a new Goal that needs to be supported.
** Excerpts from writing effective use cases by Alistair Cockburn.