designing with interaction and design class diagrams
TRANSCRIPT
Designing with Interaction and Design Class Diagrams
Chapters 15 & 16Applying UML and Patterns
Craig Larman
With some ideas fromstudents in George Blank’s
course at NJIT
Two kinds of UML Interaction Diagrams
Sequence Diagrams: show object interactions arranged in time sequence, vertically
Communication Diagrams: show object interactions arranged as a flow of objects and their links to each other, numerically
Semantically equivalent, structurally different– Sequence diagram emphasize time ordering– Communication diagrams make object linkages
explicit
Interaction Diagram notation
class instance named instance
:Sale s1:SaleSale
Which would you expect to find most often in Interaction diagrams?
What do you think of “:Sale” instead of “aSale”?
Sequence diagram notation: Register : Sale
doA
doB
doX
doC
doD
typical sychronous message shown with a filled-arrow line
a found message whose sender will not be specified
execution specification bar indicates focus of control
Figure 15.7
What does vertical placement communicate?
: Register : Sale
makePayment(cashTendered)
: Paymentcreate(cashTendered)
authorize
note that newly created objects are placed at their creation "height"
Figure 15.10
Communication Diagram: makePayment
1: makePayment(cashTendered)
1.1: create(cashTendered)
:Register :Sale
:Payment
makePayment(cashTendered)
direction of message
Figure 15.4
What do the numbers communicate?What does a create message communicate?
Communication (aka Collaboration) diagrams
Objects are rectangular icons– e.g., Order Entry Window, Order, etc.
Messages are arrows between icons– e.g., prepare()
Numbers on messages indicate sequence– Also spatial layout helps show flow
Which do you prefer: sequence or communication? Fowler doesn’t use communication diagrams
– Show flow clearly, but awkward modeling alternatives UML notation for control logic has changed in UML 2
but Fowler isn’t impressed
Control logic in Interaction Diagrams
Conditional Message– [ variable = value ] : message()– Message is sent only if clause evaluates to true
Iteration (Looping)– * [ i := 1..N ]: message()– “*” is required; [ ... ] clause is optional
Communication diagrams add Seq. Numbers before conditional messages or loops
Logic in sequence diagrams:which notation do you prefer?
calculate
: Bar
yy
xx
[ color = red ]opt
: Foo
[ color = red ] calculate
: Bar
yy
xx
: Foo
Figure 15.13
Figure 15.14
Logic in communication diagrams
1 [ color = red ] : calculate: Foo : Bar
message1
conditional message, with test
Figure 15.29
Loops in sequence diagrams:which notation do you prefer?
Figure 15.16
Figure 15.17
st = getSubtotal
lineItems[i] :SalesLineItem
t = getTotal
[ i < lineItems.size ]loop
: Sale This lifeline box represents one instance from a collection of many SalesLineItem objects.
lineItems[i] is the expression to select one element from the collection of many SalesLineItems; the ‘i” value refers to the same “i” in the guard in the LOOP frame
an action box may contain arbitrary language statements (in this case, incrementing ‘i’)
it is placed over the lifeline to which it applies
i++
st = getSubtotal
lineItems[i] :SalesLineItem
t = getTotal
loop
: Sale
Iteration in communication diagrams1 * [i = 1..n]: st = getSubtotal: Salet = getTotal
This lifeline box represents one instance from a collection of many SalesLineItem objects.
lineItems[i] is the expression to select one element from the collection of many SalesLineItems; the ‘i” value comes from the message clause.
lineItems[i]:SalesLineItem
this iteration and recurrence clause indicates we are looping across each element of the lineItems collection.
1 *: st = getSubtotal: Salet = getTotal lineItems[i]:SalesLineItem
Less precise, but usually good enough to imply iteration across the collection members
Figure 15.31
Asynchronous calls
3: runFinalization:ClockStarter System : Class
startClock
:Clock
1: create
2: runasynchronous message
active objectFigure 15.35
What’s the difference between synchronous and asynchronous?
Active object runs in its own thread of execution
Polymorphism:How is it shown in interaction diagrams?
:Register authorizedoX :Payment {abstract}
polymorphic message
object in role of abstract superclass
:DebitPayment
authorize
:Foo
stop at this point – don’t show any further details for this message
separate diagrams for each polymorphic concrete case
doAdoB :CreditPayment
authorize
:BardoX
Figure 15.34
Chapter 16 Design Class Diagrams (DCDs)
During analysis, emphasize domain concepts During design, shift to software artifacts UML has no explicit notation for DCDs Uniform UML notation supports smoother
development from analysis to design
Domain model vs. Design Class Diagram – differences?
Register
...
endSale()enterItem(...)makePayment(...)
Sale
timeisComplete : Boolean/total
makeLineItem(...)
Register
...
Sale
timeisComplete : Boolean/total
Captures
1
11Domain Model
conceptual perspective
Design Model
DCD; software perspective
currentSale
Figure 16.2
Developing a Domain Class Diagram:the NextGen POS DCD
1) Identify software classes:Register Sale ProductCatalog ProductSpecification Store SalesLineItem Payment
2) Begin drawing a class diagram3) Include the attributes from the domain model
How to show attribute collections?
notice that an association end can optionally also have a property string such as {ordered, List}
Sale
time: DateTime
...
SalesLineItem
...
...
1..*lineItems
{ordered, List}
Sale
time: DateTimelineItems : SalesLineItem [1..*] orlineItems : SalesLineItem [1..*] {ordered}
...
SalesLineItem
...
...
Two ways to show a collection attribute
Figure 16.4
4) Add method names —from interaction diagrams —model class & interaction diagrams in parallel
: Register : Sale
makePayment(cashTendered)
makePayment(cashTendered)
Register
...
makePayment(…)...
Sale
...
makePayment(…)...
1
currentSale
messages in interaction diagrams indicate operations in the class diagrams classes
identified in the interaction diagrams are declared in the class diagrams
Parameters, return types optional?—readability vs. code generation
Method body pseudo-code also optional
Register
...
endSale()enterItem(id, qty)makeNewSale()makePayment(cashTendered)
«method»// pseudo-code or a specific language is OKpublic void enterItem( id, qty ){ ProductDescription desc = catalog.getProductDescription(id); sale.makeLineItem(desc, qty);}
5) Add associations and navigability—Navigability implies visibility of attributes
How does navigability clarify this design?
What attribute does ProductCatalog implicitly contain?
6) Adding dependency relationships
Indicates that one element has knowledge of another element
I.e., a change in specification of one thing may affect another thing that uses it, but not necessarily the reverse
A dashed directed line Typically non-attribute visibility between classes
What does dependency add to this DCD?
SalesLineItem
...
...
ProductDescription
...
...
1..*lineItems
Sale
...
updatePriceFor( ProductDescription )...
the Sale has parameter visibility to a ProductDescription, and thus some kind of dependency
Composition (whole-part) relations
Finger0..7
Hand
composition
1
Square40
Board1
SalesLineItem1..*Sale1
composition means -a part instance (Square) can only be part of one composite (Board) at a time
-the composite has sole responsibility for management of its parts, especially creation and deletion
Figure 16.13
Association classes—model association with attributes & operations
salarystartDate
Employment
EmploysCompany Person**
a person may have employment with several companies
Figure 16.16
«interface»List
clear()...
Kparameterized or template interfaces and classes
K is a template parameter
anonymous class with template binding complete
Board
squares : List<K Square> orsquares : List<Square>...
ArrayList<T Square>
clear()...
the attribute type may be expressed in official UML, with the template binding syntax requiring an arrow orin another language, such as Java
ArrayList
elements : T[*]...
clear()...
T
for example, the elements attribute is an array of type T, parameterized and bound before actual use.
there is a chance the UML 2 “arrow” symbol will eventually be replaced with something else e.g., ‘=’
Interfaces and Template Classes—Interface is a predefined «stereotype»—Templates take parameters in corner
Figure 16.18
DCD summary
Questions?
java.awt::Fontor
java.awt.Font
plain : Int = 0 { readOnly }bold : Int = 1 { readOnly }name : Stringstyle : Int = 0...
getFont(name : String) : FontgetName() : String...
«interface»Runnable
run()
- ellipsis “…” means there may be elements, but not shown- a blank compartment officially means “unknown” but as a convention will be used to mean “no members”
SubclassFoo
...
run()...
SuperclassFooor
SuperClassFoo { abstract }
- classOrStaticAttribute : Int+ publicAttribute : String- privateAttributeassumedPrivateAttributeisInitializedAttribute : Bool = trueaCollection : VeggieBurger [ * ]attributeMayLegallyBeNull : String [0..1] finalConstantAttribute : Int = 5 { readOnly }/derivedAttribute
+ classOrStaticMethod()+ publicMethod()assumedPublicMethod()- privateMethod()# protectedMethod()~ packageVisibleMethod()«constructor» SuperclassFoo( Long )methodWithParms(parm1 : String, parm2 : Float)methodReturnsSomething() : VeggieBurgermethodThrowsException() {exception IOException}abstractMethod()abstractMethod2() { abstract } // alternatefinalMethod() { leaf } // no override in subclasssynchronizedMethod() { guarded }
3 common compartments
1. classifier name
2. attributes
3. operations
interface implementation andsubclassing
Fruit
...
...
PurchaseOrder
...
...
1
association with multiplicities
dependency
officially in UML, the top format is used to distinguish the package name from the class name
unofficially, the second alternative is common
order
an interface shown with a keyword
Figure 16.1
Designing with interaction and class diagrams
Beginners often emphasize Class diagrams Interaction diagrams deserve more attention Some tools can help:
– Convert between sequence and communication diagrams automatically
– Reflect changes in class and interaction diagrams in parallel