Thursday, May 12, 2011

A Taxonomy of Use Case Errors

First, the definition. A use case describes an actor's interaction with a system to create business value. There are three parts: Actor, Interaction and Business Value.

1. Not Interactive.
1.1. The use case is just features and technical attributes with no actor interaction expressed.
1.2. The use case is just algorithms and processing with no connection to an actor or a goal.

2. No Business Value.
2.1. Incomplete
2.1.1. The use case focus on sequential operations with no value or goal.
2.1.3. The use case simply follows existing precedent without supporting actual business goals. It "paves the cow path".
2.2. Non-Specific
2.2.1. The use case is a result of free-running imagination; it conflates "possibly" vs. "required". It contains descriptions of interactions which could happen or would be nice to happen.
2.3. Covers the Technology Only
2.3.1. The solution technology is conflated with the business problem. Words like "database" or "foreign key" or "error log" or other solution technology are central.
2.4. Contradictory
2.4.1. The use case goal contradicts other goals.
2.4.2. The use case sequence is inconsistent with the stated goal.

3. No Actor.