Post on 16-Dec-2015
transcript
SYS366
The Last Stage in Analysis:System Use Case Descriptions
created through the Use Case Authoring Process
Where did we come from? Identified Stakeholder categories/types Identified business areas & basic processes Completed interviews with stakeholder rep. Identified Business Use Cases Built a Business Use Case Diagram Wrote Business Use Case Descriptions Created Actor/Activity Tables from the
Business Use Case Descriptions
System Use Cases Identify actors for System Use Cases
look for an actor who specifically interacts with the system humans, devices, other systems, etc
Actors are not part of the system. They are just outside the system boundary and are visible to the system.
Identify activities for System Use Cases Anything the system must do to achieve the use case
result Happens only inside the system boundary
Systems Use Case Diagram Systems Use Case Descriptions Systems Use Case Authoring Process
Systems Use Cases convert Business Use Cases
to system requirements. How?
B.U.C. description leads to B.U.C. actor/activity table leads to System Use Case Diagram &
Description
Documenting Systems Use Cases Systems Use Case Diagram
Shows the functionality that the system will provide and which users (actors) will communicate with the system
Done using Rational Rose acts as a place holder for the
Systems Use Case Description is a visual index, providing a context
for the descriptions
Systems Use Cases Diagram Actors are represented by
a ‘stick’ figure
Systems Use Cases are shown as an oval
Associations are a customer ID labeled arrow line —–—–––
Designing Dialogs
The process of designing the overall sequences that users follow to interact with an information system
the sequence in which information is displayed to and obtained from the user
Sequence
understanding how the user will interact with the system clear understanding of user, task,
technological and environmental characteristics
Systems Use Case Descriptions The (systems) use case descriptions
provide the substance of the (systems) use case model and they are the basis for most of the …modeling work…More than 90% of the (systems) use-case model lies beneath the surface, in the textual use-case descriptions themselves. *
*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 30
Systems Use Case Descriptions “(Systems) use cases are more than
just a named ellipse and a brief description. For each (systems) use case there will also be a (systems) use-case description where the full story of the use case is told.”*
*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 30
Systems Use Case Descriptions “The use case description tells a story of
how a system and its actors collaborate to achieve a specific goal
This collaboration takes the form of a dialog between the system and its actors
It is a step-by-step description of a particular way of using a system”*
*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 24
Systems Use Case Descriptions “Just like a story, every use case should
have a clear beginning (how the actor starts
the use case) Middle (how the system and actors
work together) End how the use case is concluded”*
*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, p. 24
Systems Use Case Description Describes typical ways (or cases) of using
the system* with processing details Not a complete description of all possible
ways that some task is performed by actor Does not say how the system is designed or
implemented (e.g. J2EE or .NET)
*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, pp. 24-25
Systems Use Case Descriptions
The systems use case description must include:
Who the actors are and how many of them are interacting with the system at any point in time
What data is used and how All normal logic: sequential, decision,
looping All exception and error logic
Today Systems Use Case Descriptions Systems Use Cases Authoring
Systems Use Cases Authoring The Systems Use Cases and its
description evolves through the authoring process.*
*Systems Use Cases Modeling by Bittner & Spence, Page 152
The Authoring Life Cycle
Discovered Briefly Described
BulletedOutline
EssentialOutline
DetailedDescription
Systems Use CaseSpecification
The Authoring Life Cycle State 1: Discovered *
Through Interviews with the Stakeholders
Through experience Shown on a Systems Use Case diagram
Place holder for the Systems Use Case description
A visual index, providing a context for the descriptions
*Systems Use Cases Modeling by Bittner & Spence, Pages 153 - 154
The Authoring Life Cycle State 2: Briefly Described
Once the Systems Use Case has been identified, it should be described
Example: Create Vehicle Reservation by Phone
This Systems Use Cases describes how the actor, a Call Centre Employee, uses the system to reserve a vehicle for a specified period at a customer’s request.
The Authoring Life Cycle State 3: Bulleted Outline
Captures the simple steps of the use case in short sentences organized sequentially
Bulleted Outline Example of a Systems Use Case
Bulleted Outline Let’s create a bulleted outline for
one of your use cases