Best Practices for Writing Use Cases

Are your use cases clear both for your users and for your developers ? Here are some tips:

• Be careful with UML diagrams. Only use them for a high level model to show relationships between actors and use cases. Use case descriptions are textual
  
• Main scenario 3-9 steps. Bird's eye view
• No IF-statements, but main scenario's plus extensions
  
• Brainstorm on goal failures
• evaluate, eliminate, merge
• Manage your energy: work breadth first
  
• Actors and goals
• Use case brief, main scenario
• Failure conditions
• Failure handling
• Goal based, find the right goal. 3 levels: summary, user goals, subfunctions
  
• What does the primary actor really want ?
• WHY is this actor doing this step/goal ?
• Write short, clear, easy to read use cases
• Use cases are communication instruments
• Customers/Users: Is it this what you want ?
• Developers: Can you develop this ?
• Like "Actors verbs the system", ie. Customer debets his account
  
• Use Cases describe the functional requirements of a system, other requirements are described in supplementary specifications: performance, user interface requirements, IO formats, data formats, ...

With which of these tips can you improve your use cases ? Or do you have other tips ?

To learn more about writing use cases: Writing Effective Use Cases, by Alistair Cockburn, Addison-Wesley 2001.

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