Use Case Realisation Flashcards
What is a helicopter view in systems design?
An approach starting with the big picture (highly abstracted) and gradually working into finer details (decreasing abstraction).
What are use case realisations?
Formalisation of use cases through descriptions, user stories, or diagrams (e.g., UML).
How do descriptions and user stories differ?
Descriptions generalise the use case, while user stories detail specific scenarios.
What does a use case description include?
Basic flow of events from the actor’s perspective, alternate paths, and exception paths.
What is a successful use case?
A use case that delivers measurable value to the actor, possibly through alternate paths.
What is an unsuccessful use case?
A use case where the actor receives no measurable or negative value, often due to exception paths.
How are business-level use cases modelled?
Start with a business-level diagram, then write descriptions showing how business workers realise the use cases.
What is the purpose of a UML use case model?
To identify actors, their interactions with the system, and the frequency of different use cases.
What are preconditions in use cases?
Conditions that must be true before a use case starts.
What are postconditions in use cases?
Conditions that must be true after a use case ends.
What are business rules?
Fixed constraints or guidelines defining the operation of a business process.
What enforces business rules?
External legislation, internal strategy, or established practices/customs.
What are examples of business rules?
Credit checks for all new customers; valid NHS numbers for patients in the NHS system.
How do business rules relate to systems?
They are independent but must be supported by current systems, which may need updates when rules change.
What is an activity diagram?
A flowchart illustrating successful, alternative, and exception paths for a use case.
