Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 1 Capturing the Requirements as use Cases  Requirements Description  We need to describe –The artifacts created in the requirements workflow –The workers participating in the requirements workflow –The requirements capture workflow activities.  Fig 7.1 p. 133

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 2 Artifact: Use-Case Model  The system's functional requirements  The conditions or capabilities to which the system must conform  Agreement between the customer and the developer  Essential input for analysis, design, and testing  May be broken up into packages

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 3 Artifact: Actor  Actors represents parties outside the system that collaborate with the system  Actors correspond to workers and/or business actors in a business  An actor plays one role for each use case which it collaborates  An instance of an actor is a specific user interacting with the system

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 4 Artifact: Use Case  A use case represents one way in which the actors use the system  A use case is a chunk of functionality that the system offers to add a result of value to its actors.  A use case specifies a sequence of actions, including alternatives of the sequence, that the system can perform, interacting with actors of the system.  Use-case instance –A use case specifies the behavior of dynamic use-case instances or a scenario of use of the system –A use-case instance is the performance or execution of a use case –A use-case instance interacts with an actor instance –A use-case instance does not interact with another use-case instances

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 5 Artifact: Architecture Description  An architectural view of the use-case model.  It depicts the architecturally significant use cases.  An architecturally significant use case has some important and critical functionality, or involves some important requirement that must be developed early in the software's life cycle.  The architectural view is used as input when use cases are prioritized to be developed within an iteration.

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 6 Artifact: Glossary  To define important and common terms used by analysts to describe the system  Useful in reaching a consensus among developers –Regarding the definitions of various concepts and notions, and –Reducing the risk of misunderstandings  It can be derived from a business or domain model  It is more focused on the system to be built instead of the system's context.

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 7 Artifact: User-Interface Prototype  Help understand and specify the interactions between human actors and the system.  One user-interface prototype for each use case.

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 8 Workers  A worker is a position in the unified development process to which a real person can be assigned.  With each worker there is a description of the responsibilities and the expected behavior of that worker.

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 9 Worker: System Analyst  Responsible for –The whole set of requirements that are modeled as use cases –Delimiting the system –Finding the actors and use cases –Ensuring that the use-case model is consistent and complete –The modeling leader and coordinator  Not responsible for –Individual use cases

Gerhard Dueck -- CS3013Capturing Requirements as Use Cases 10  Worker: Use-Case Specifier –Responsible for the detailed description of one or more of the use cases. –Work closely with the real users of the use case that s/he is responsible.  Worker: User-Interface Designer –Responsible for »visually shaping the user interface developing, for each actor, a user-interface prototype for some use cases  Worker: Architect –Responsible for describing the architectural view of the use-case model.