bts430 systems analysis and design using uml interaction diagrams
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BTS430 Systems Analysis and Design using UML
Interaction Diagrams
Definition
An interaction diagram illustrates how objects interact using messages for a given scenario.
UML has two main types—sequence and communication.
Definition
Interaction diagrams “force us to think through the concrete details of what messages to send and to whom and in what order”. text, p.225
They define how we meet our “operation contracts”.
Sequence Diagrams
: Register : Sale
makePayment(cashTendered)
makePayment(cashTendered)
: Paymentcreate(cashTendered)
UI Layer
Domain Layer
Sequence Diagrams
:ProcessSaleFrame
UI Layer
Domain Layer
makePayment(cashTendered)
: Register : Sale
makePayment(cashTendered)
makePayment(cashTendered)
: Paymentcreate(cashTendered)
makePayment(cashTendered)
Participants
Lifeline Boxes (roughly equal to class instances)
Common cases of notation:
:Sale s1:Sale
unnamed instance named instance
Messages
Occur between objects Starting messages are initiated by a random
source or a specific source
:Register :Register
Random Source Specific Source
Message Expression Syntax
see page 227 Examples:
startSale() or startSale desc=getDescription(itemID) OR
getDescription(itemID), with “product description” shown as a return
Returns
:Register :Sale
makePayment(cashTendered)
change due
makePayment(cashTendered)
OR
changeDue=makePayment(cashTendered)
Object Creation
:Register :Sale
makePayment(cashTendered)
:Paymentcreate(cashTendered)
makePayment(cashTendered)
invokes the “new” operator and calls the constructor:public class Sale{private Payment payment;public void makePayment( Money cashTendered ){ payment = new Payment( cashTendered );….and so on
Object Destruction
:Register :Sale
makePayment(cashTendered)
:Paymentcreate(cashTendered)
makePayment(cashTendered)
Payment object destroyed
…
<<destroy>>
X
Messages to Self
:Register
newSale()
clear()
…