Www.ddss.arch.tue.nl 7M822 UML Sequence Diagrams 5 October 2009.

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7M822

UML Sequence DiagramsUML Sequence Diagrams

5 October 2009

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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• Collaboration diagram

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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• Collaboration diagram

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Behaviour modellingBehaviour modelling

• Behaviour models are used to describe the overall behaviour of the system.

• Objects interact to implement behaviour. This interaction can be described in two complementary ways, one of them is centred on individual objects and the other on a collection of cooperating objects.

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from: Fowler & ScottUML distilled, 2nd edition.

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Interaction diagramsInteraction diagrams

• Interaction diagrams are models that describe how groups of objects collaborate in some behaviour.

• Two kinds of interaction diagrams: – sequence diagrams– collaboration diagrams

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from: Fowler & ScottUML distilled, 2nd edition.

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Sequence diagramSequence diagram

• A sequence diagram captures the behaviour of a scenario.

• The diagram shows a number of objects and the messages that are passed between these objects within the use case.

• A sequence diagram shows a set of messages arranged in time sequence.

:Inputcontroller :Alarm :Timer :Zoomer

:Person

Wake-up time()

On()

On()

Wake-up Time()

Start()

Start()

Off()Off()

Stop()

It is Time()

Buzz()

StopBuzz()

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Concepts sequence diagramsConcepts sequence diagrams

:Computer :PrinterServer :Printer :Queue

Print()

Print (file)()

[printer available] Print (file)()

[printer working] Save (file)()

()

()

()

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Concepts sequence diagramsConcepts sequence diagrams

:Computer :PrinterServer :Printer

Print (ps file)()

Print (ps file)()

[no queue] Print (ps file)()

()

()

elementary message activation

synchronic message

return

lifeline

object

control guard

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Concepts sequence diagramsConcepts sequence diagrams

:Computer :PrinterServer :Printer

Print (ps file)()

Print (ps file)()

Print (ps file)()

()

()

{ a

b-a < 5 secb

b'-b < 1 secb'

}

constraint

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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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Elements sequence diagramsElements sequence diagrams

Object1 Object Lifeline Activation Lifeline

Message() Message()Self back()

Return() Return()

Message()

{}

constraint comment

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from: Fowler & ScottUML distilled, 2nd edition.

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from: Fowler & ScottUML distilled, 2nd edition.

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from: Fowler & ScottUML distilled, 2nd edition.

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NS Ticket serviceNS Ticket service

Take ticket

Destination

Traveller

Buy OV ticket

Buy NS ticket

Pay ticket

«extends»

«uses»

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Class diagram of ‘NS ticket service’ including the classes ‘Ticket’ and ‘Destination’

Class diagram of ‘NS ticket service’ including the classes ‘Ticket’ and ‘Destination’

+create()+payPrice()+printTicket()

-fromStation-toStation-oneWay : Boolean-reduction : Boolean-class-date : Date-price : Currency

Ticket

+validateDestination()+showPrice()

-code-name-distance-base price

Destination

+Print()+checkStatusPrinter()

-statusPrinter

Printer

* 1

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NS Ticket machine – use case textNS Ticket machine – use case textUse Case Buy OV Ticket

Actors Traveller

Preconditions Traveller has a valid pass

Description 1. Ticket device expects destination code

2. Traveller enters destination code

3. Extension point: NS ticket

4. Ticket device checks code and calculates the charge. Shows destination code & fare. Activates ticket machine for paying

5. Traveller pays (use case: Pay ticket)

6. Ticket device print and supplies ticket

7. Traveller takes ticket

Extension Destination code = NS station.

3a. Ticket device expects ticket type

3b. Traveller enters Single/Return, Discount Y/N, Class

Exceptions Traveller interrupt the interaction or walk away

Traveller enters an incorrect destination code

Payment is not finished off successful

Result Traveller has ticket.

(NS can look forward to the payment)

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Sequence diagram – Buy ticketSequence diagram – Buy ticket:Traveller :Destination :Ticket :Payment :Ticketprinter

Choose Destination()Choose Destination()

Push button()

Perform Payment()

Execute printtask()

Put Ticket()

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Elevator ExampleElevator Example

Scenario• User pressed floor button• Elevator system detects floor

button pressed• Elevator moves to floor• Elevator open doors• User gets in and press elevator

button• Elevator moves to required floor• Elevator open doors• User gets out• Elevator close doors

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