Introduction to the Sequence Diagrams

with stereotypes

Department of Information Systems and Computation (DSIC)

Valencia Polytechnic University

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Requirements Analysis ProcessSequence Diagram A Use Case functionality is specified identifying interacting classes

and messages that they interchange

Structure and Notation

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Requirements Analysis ProcessSequence Diagram

Blocks: they are used to specify conditions or iterations that affect to one or many messages

NOT ALL the messages are of the same nature…

An UML extension is introduced (stereotypes) to classify messages according to its nature: «signal» , «service» , «query» , «connect»

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Sequence DiagramStereotypes extension

«Signal» stereotype

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Sequence DiagramStereotypes extension

«Service» stereotype

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Sequence DiagramStereotypes extension

«Query» stereotype

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Sequence DiagramStereotypes extension

«Connect» stereotype

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Sequence DiagramStereotypes extension

«Connect» stereotype example

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An example

2- Functionality is specified identifying object classes and interactions

1- Use Case is identified and its actor(s) specified

Saleitems

Cashier

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RAP – Sequence Diagram (1/8) (Relevant actors are identified)

Saleitems

Cashier

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RAP – Sequence Diagram (2/8) (Messages between actors and the system)

Saleitems

Cashier

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RAP – Sequence Diagram (3/8)(Internal messages, Sale and Sale-line are identified)

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RAP – Sequence Diagram (4/8)(To create a sale-line it’s necessary an item)

until end of linesuntil end of lines

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RAP – Sequence Diagram (5/8)(the cashier finishes the data entry)

until end of linesuntil end of lines

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RAP – Sequence Diagram (6/8)(Subtotal has to be calculated and also the item stock has to be updated)

until end of linesuntil end of lines

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RAP – Sequence Diagram (7/8)(Final information about the sale is shown)

until end of linesuntil end of lines

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RAP – Sequence Diagram (8/8)(Messages are stereotyped)

<<signal>><<signal>>

<<signal>><<signal>>

<<service/new>><<service/new>>

<<service/new>><<service/new>>

<<connect/1,1>><<connect/1,1>>

<<query>><<query>>

<<query>><<query>>

<<service>><<service>>

<<signal>><<signal>>

<<signal>><<signal>>

until end of linesuntil end of lines

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Summary Sequence Diagrams (SD) are used to specify functionality in terms of

object interactions (they are not algorithm specifications!) Objects from classes communicate each other by sending messages

A SD is structured in three regions: External: actors outside of the system – users Interface: user interface (boundary class) to receive information from

actors or to show information produced by the system Internal: classes in which the system is structured

Depending on the nature of messages they are classified in: Signal: messages to get information into the system or to show

information from the system Service: messages that change the state of the system (create, destroy,

update) Query: messages to query the state of an object or a set of objects Connect: messages that relates objects to each other (when an object

needs to be “connected” to other objects)