♦ Use Case -What are the domain processes ? Use Case Diagram
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♦ Use Case -What are the domain processes ? • Use Case Diagram ♦ Conceptual Model -What are the domain concepts, terms ? • Class Diagram (conceptual) • classes, associations, attributes 1 Summary from previous lectures
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Summary from previous lectures. ♦ Use Case -What are the domain processes ? Use Case Diagram ♦ Conceptual Model -What are the domain concepts, terms ? Class Diagram ( conceptual ) classes , associations, attributes. Fig 10.1 Summary from previous lectures. System Sequence Diagrams. - PowerPoint PPT Presentation
Transcript of ♦ Use Case -What are the domain processes ? Use Case Diagram
♦ Use Case -What are the domain processes ?• Use Case Diagram
♦ Conceptual Model -What are the domain concepts, terms ?
• Class Diagram (conceptual)• classes, associations, attributes
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Summary from previous lectures
Operation: enterItem(…)
Post-conditions:- . . .
Operation Contracts
Sale
date. . .
SalesLineItem
quantity
1..*1 . . .
. . .
Domain Model
Use-Case Model
Design Model: Register
enterItem(itemID, quantity)
: ProductCatalog
spec = getProductSpec( itemID )
addLineItem( spec, quantity )
: Sale
Require-ments
Business Modeling
Design
Sample UP Artifact Relationships
: System
enterItem(id, quantity)
Use Case Text
System Sequence Diagrams
makeNewSale()
system events
Cashier
Process Sale
: Cashier
use case
names
system operations
Use Case Diagram
Vision
SupplementarySpecification
Glossaryparameters and
return value details
starting events to design for
Process Sale
1. Customer arrives ...2. Cashier makes new sale.3. ...
Fig 10.1 Summary from previous lectures
System Sequence Diagrams
Chapter 10Applying UML and Patterns
-Craig Larman
Introduction Class diagrams represent static relationships.
What about modeling dynamic behavior? Interaction diagrams(Sequence and
communication diagrams) model how groups of object collaborate to perform some behavior• Typically captures the behavior of a single
use case
Today´s lecture
System Sequence Diagram (SSD)For a use case scenario, an SSD shows: The System (as a black box) The external actors that interact with System The System events that the actors generate SSD shows operations of the System in
response to events , in temporal order Develop SSDs for the main success scenario of
a selected use case, then frequent and salient alternative scenarios
:System
Identifying the right Actor
In the “Process Sale” example, does the
customer interact directly with the POS system?
Who does?
Cashier interacts with the system directly
Cashier is the generator of the system events
Fig 10.2 SSD for a Process Sale scenario
enterItem(itemID, quantity)
:System: Cashier
endSale
makePayment(amount)
a UML loop interaction frame, with a boolean guard expression
external actor to system
Process Sale Scenario
system as black box
the name could be "NextGenPOS" but "System" keeps it simple
the ":" and underline imply an instance, and are explained in a later chapter on sequence diagram notation in the UML
a message with parameters
it is an abstraction representing the system event of entering the payment data by some mechanism
description, total
return value(s) associated with the previous message
an abstraction that ignores presentation and medium
the return line is optional if nothing is returned
total with taxes
change due, receipt
makeNewSale
[ more items ]loop
Relationship between SSD and Use case
System Sequence Diagrams :♦ Draw a line representing the system as a black box.♦ Identify each actor that directly operates on the system. Draw a line for each such actor.♦ From expanded use case identify system events that each actor generates.Illustrate them.♦ Optionally include use case text on left.
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Fig 10.3 Relationship between SSD and Use case
Naming System events & operations
System events and associated system operations
should be expressed at the level of intent.
Rather than physical input medium or UI widget
Start operation names with verb (from use case)
Which is better, scanBarCode or enterItem?
Fig 10.4 : Naming System events & operations
enterItem(itemID, quantity)
scan(itemID, quantity)
: Cashier
worse name
better name
:System
Capture the intent of the operation while remaining abstract
Fig 10.5 SSD for ”play Monopoly” Game scenario
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SSDs and the Glossary in parallel Why is updating the glossary important
when developing the SSD? New terms used in SSDs may need
explanation, especially if they are not derived from use cases
A glossary is less formal, easier to maintain and more intuitive to discuss with external parties such as customers
Why Draw SSD? Important to know the system events.
Sequence diagrams help the designer to
determine how the system will react to each event.
Need to design the software to handle these
events and execute a response.
Example 1
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Questions ?
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