sys366 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
SYS366 PowerPoint Presentation
Download Presentation
SYS366

Loading in 2 Seconds...

play fullscreen
1 / 33

SYS366 - PowerPoint PPT Presentation


  • 94 Views
  • Uploaded on

SYS366. Last Lecture System Use Descriptions created through Use case Authoring. Today. Systems Use Case Descriptions Systems Use Case Authoring. Systems Use Case Diagrams and Descriptions. Based on the dialog metaphor. Dialog Expresses that the User and Computer

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'SYS366' - shellie-phelps


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
sys366

SYS366

Last Lecture

System Use Descriptions

created through Use case

Authoring

today
Today
  • Systems Use Case Descriptions
  • Systems Use Case Authoring
systems use case diagrams and descriptions
Systems Use Case Diagrams and Descriptions
  • Based on the dialog metaphor
designing dialogs
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
Sequence
  • understanding how the user will interact with the system
    • clear understanding of user, task, technological and environmental characteristics
systems use case descriptions
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 descriptions1
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 descriptions2
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 description
Systems Use Case Description
  • Not a complete description of all possible ways that some task is performed
  • Does not say how the system is designed or implemented
  • Describes typical ways (or cases) of using the system*

*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, pp. 24-25

systems use case descriptions3
Systems Use Case Descriptions
  • Systems use Case descriptions are required to define, in detail, the processing that needs to happen in each use case
systems use case descriptions4
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
    • All exception and error logic
today1
Today
  • Systems Use Case Descriptions
  • Systems Use Cases Authoring
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
The Authoring Life Cycle

Discovered

Briefly

Described

Detailed

Outline

Essential

Outline

Bulleted

Outline

Systems Use Case

Description

the authoring life cycle1
The Authoring Life Cycle
  • State 1: Discovered *
    • Through the Actor/Function/Use Case Table
    • 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 cycle2
The Authoring Life Cycle
  • State 2: Briefly Described
    • Once the Systems Use Case has been identified, it should be described
the authoring life cycle3
The Authoring Life Cycle
  • State 3: Essential Outline
    • Focuses on only the most important behaviour of the system
    • Presents a “black box” view of the system in order to focus on getting right what the system must do
    • Emphasizes usability
      • Helps describe user intent and actions, along with the observable response of the system
      • Does not describe what is happening inside the system
the essential outline
The Essential Outline
  • Stripped down essential outlines capture the essence of the required dialog without forcing the designers into any particular technology or mode of interaction
the detailed description
The Detailed Description
  • State 4: Detailed Description
    • Start adding to the (Essential) outline the detail required to complete the Description of the system
    • Here the use case is evolving as more and more detail is added to flesh out the outline
the use case description
The Use Case Description
  • State 6: Fully Described
    • The final state in the evolution of a use case
    • The use case has a complete flow of events
    • Unambiguously defines all of the inputs and outputs involved in the flow of events.
use case descriptions
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

use case descriptions1
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

use case descriptions2
Use Case Descriptions
  • The major sections of a use case Description are:
    • Brief Description
    • Precondition statement
    • Main flow
    • Subflows
    • Exceptions
    • Successful post conditions
the main flow
The Main Flow

The main flow describes:

  • How the use case starts
  • What events initiate system activity
  • What system activity each event initiates

The main flow describes the logic that controls the use case activity

subflows
Subflows
  • Describe a piece of system activity
  • Only some subflows are initiated from the main flow
  • Subflows can initiate other subflows or they can initiate another use case
subflows1
Subflows
  • Must be specific. You must describe how each ends.
  • A subflow might:
    • Restart itself, another subflow or the use case
    • Continue the use case from the insertion point
    • End the use case
    • Launch another use case
exceptions
Exceptions
  • Describe how the system handles user errors and unexpected system responses
use case description
Use Case Description
  • Not a complete description of all possible ways that some task is performed
  • Does not say how the system is designed or implemented
  • Describes typical ways (or cases) of using the system*

*Use Case Modeling, Kurt Bittner & Ian Spence, Addison-Wesley, 2003, pp. 24-25

the use case description1
The Use Case Description
  • Fully Described
    • One of the best checks of whether a use case Description is finished is to ask if you could use the use case to derive system tests.
the use case description2
The Use Case Description
  • Fully Described
    • The best way to tell if the use cases fit the purpose is to pass them along to the …test team for test design.
    • If the team is satisfied that they can use the use cases to support this activity, then the use case Description contains sufficient levels of detail.
the use case description3
The Use Case Description
  • State 6: Fully Described
    • One of the best checks of whether a use case Description is finished is to ask if you could use the use case to derive system tests.
    • The best way to tell if the use cases fit the purposed is to pass them along to the
use case description1
Use Case Description
  • Place Bid Example