www.ddss.arch.tue.nl 7m822 uml sequence diagrams 2 december 2010

www.ddss.arch.tue.nl

7M822

UML Sequence DiagramsUML Sequence Diagrams

2 December 2010


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UML DiagramsUML Diagrams

• Structure diagram– Class diagram– Object diagram– Component diagram– Deployment diagram– Package diagram

• Behaviour diagram– Use Case diagram– Activity diagram– Interaction diagram

• Sequence diagram• Communication diagram

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In a nutshell: what are interactions?In a nutshell: what are interactions?

• A collection of communications between instances, including all ways to affect instances, like operation invocation, as well as creation and destruction of instances

• The communications are partially ordered (in time)

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Interaction Diagram GuideInteraction Diagram Guide

• Show interactions between instances in the model– graph of instances (possibly including links) and stimuli– existing instances– creation and deletion of instances

• Kinds– Sequence diagram (temporal focus) – Communication diagram (structural focus)

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Interaction DiagramsInteraction Diagrams

5

x y z

Sequence Diagram

a

b

c

Communication Diagram

x y

z

1.1: a1.2: c

1.1.1: b


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Different Kinds of ArrowsDifferent Kinds of Arrows

Procedure call or other kind of nested flow of control (synchronous message)

Return

Asynchronous message

Asynchronous message in UML 1.x

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Lifeline & MessagesLifeline & Messages

• The vertical line is called the object’s lifeline. The lifeline represents the object’s life during the interaction.

• Each message is represented by an arrow between the lifelines of two objects.

• The order in which these messages occur is shown top to bottom.

• Each message is labeled at minimum with the message name; also arguments and some control information can be included.

• A self-back is a message that an object sends to itself, by sending the message arrow back to the same lifeline.

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Sequence Diagram / Communication DiagramSequence Diagram / Communication Diagram

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an Order an Order Line aProduct aCustomer

calculatePricegetQuantity

getProduct

aProduct

getPricingDetails

calculateBasePrice

calculateDiscounts

getDiscountInfo

found message

return

self-call

activation

lifeline

message

participant

an Order aCustomer

an Order Line aProduct

1: calculatePrice

1.5.1: getDiscountInfo

1.3: getPricingDetails

1.4: calculateBasePrice()1.5: calculateDiscounts()

1.1: getQuantity()1.2: getProduct()


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Sequence Diagram vs. Communication DiagramSequence Diagram vs. Communication Diagram

• Sequence diagrams are used when you want to look at the behavior of several objects within a single use case. Sequence diagrams are good at showing collaborations among the objects.

• Communication diagrams emphasize the data links between the various participants in the interaction. With communication diagrams we can show how the participants are linked together.

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Elements Sequence DiagramsElements Sequence Diagrams

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Participant : Object

Participant / ObjectLifeline Activation Lifeline

Message Message Self back

Return Return

{}

Constraint Comment


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Next Concepts Sequence Diagrams 1of2Next Concepts Sequence Diagrams 1of2

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:Computer :PrinterServer :Printer :Queue

PrintPrint(file)

[printer available] Print(file)

[printer working] Save(file)

control guard


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Next Concepts Sequence Diagrams 2of2Next Concepts Sequence Diagrams 2of2

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:Computer :PrinterServer :Printer

PrintPrint(file)

Print(file){

ab-a < 5 sec

bb'-b < 1 sec

b' }

constraint


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: Order Entry Window : Order Line: Order : Stock Item

: Reorder Item

: Delivery Item

SEQUENCEDIAGRAM


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: Transaction

: Transaction Coordinator

: first Transaction Checker

: second Transaction Checker Concurrent

Processes andActivations


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: Transaction

: Transaction Coordinator

: first Transaction Checker

: second Transaction Checker

SEQUENCEDIAGRAM:Check Failure


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Example: A Booking SystemExample: A Booking System


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Use Case Description: Change Flt ItineraryUse Case Description: Change Flt Itinerary• Actors: traveler, client account db, airline reservation

system• Preconditions: Traveler has logged in• Basic course:

– Traveler selects ‘change flight itinerary’ option– System retrieves traveler’s account and flight itinerary from client account database– System asks traveler to select itinerary segment she wants to change; traveler selects

itinerary segment.– System asks traveler for new departure and destination information; traveler provides

information.– If flights are available then …– …– System displays transaction summary.

• Alternative course:– If no flights are available then…


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Sequence Diagram: Change Flight ItinerarySequence Diagram: Change Flight Itinerary

: Booking SystemTraveler Airline Reservation System

change flight itinerary

get customer account

get itinerarypresent itinerary

select segment

present detailed info

update informationavailable flight

Client Account DBMSClient Account DBMS


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Collaboration Diagram: Change Flt ItineraryCollaboration Diagram: Change Flt Itinerary

Traveler Client Account DBMS

Airline Reservation System

: Booking System

7: update information

2: get customer account3: get itinerary

4: present itinerary

8: available flight

1: change flight itinerary5: select segment

6: present detailed info

www.ddss.arch.tue.nl 7m822 uml sequence diagrams 2 december 2010

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