Object-oriented modeling - PowerPoint Presentation

Slide1

Object-oriented modelingSequence diagrams

Karolina Muszyńska

Based on

: S. Wrycza, B. Marcinkowski, K. Wyrzykowski „Język UML 2.0 w modelowaniu SI”Slide2

Dynamic view – sequence diagramsrole and types of sequence diagramsbasic concepts

advanced conceptsexamples2

Object ModelingSlide3

Sequence diagram is a kind of interaction diagram, describing interactions among system classifiers in the form of sequence of messages interchanged between them during a certain period of time.

Sequence diagrams are closely related to use case scenarios as they document their functionality.Interaction is shown on the sequence diagram in two dimensions:

Horizontal - static dimension

where the system classifiers taking part in the interaction are placed

Vertical – dynamic dimension

, with the time line showing chronically arranged messages

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Sequence Diagram –roleSlide4

Depending on the degree of abstraction three types of sequence diagrams can be specified:

Conceptual sequence diagram – using only basic concepts, for quick and general overview of the system interactionsGeneric sequence diagram – is the basis for software specification and uses all available concepts; this type of diagram includes the main and all alternative scenarios of a use case and it can be used for automatic generation of program code

Instance sequence diagram

– a diagram describing one particular scenario of a use case; there may be several instance diagrams for one generic diagram

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Sequence Diagram

s

–typesSlide5

Classifier – abstract category of system modeling in UML (e.g.

actor, object,

interface

, component, package, etc.)

Message

– describes a control flow in the system; it determines the sequence and place of execution of operations; messages are arranged according to the sequence of their appearance – the later they occur the lower they appear on the diagram

Each classifier has a

lifeline that represents its life time; the “X” mark at the end of the lifeline indicates the point at which the object ceases to exist in the system

The

execution specification

shows time period during which the classifier performs an operation (processing, calculating, communicating with other classifiers or executing complex algorithms); the execution specification is initiated with an activation and ended with deactivation.

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Sequence Diagrams –basic conceptsSlide6

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Sequence

Diagrams –basic concepts

Classifier

(actor, object, interface, package)

Message

LifelineSlide7

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Sequence

Diagrams –basic concepts

Activation

Execution specification

DeactivationSlide8

Types of messages

Creating and destroying objectsGuard conditions

Combined fragments with interaction operators

Interaction occurrences

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Sequence Diagrams –

advanced conceptsSlide9

Message types:synchronous message – passes control from the sender classifier to the receiver classifier

asynchronous message – does not pass control, does not wait for an answer from the receiver, may continue processingreturn message – indicates control return to the sender classifier after synchronous message and may also initiate a certain operation

self message

– message sent by the classifier to itself resulting in calling its own operation; self message is a certain kind of iteration, which creates a nested execution specification

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Sequence Diagrams – advanced conceptsSlide10

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Sequence Diagrams – advanced concepts

Asynchronous message

Synchronous messageSlide11

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Sequence Diagrams – advanced concepts

Self message

Return

messageSlide12

Other message types:lost message – message sent from a known sender to an unknown receiver (temporary message)

found message – message whose sender is unknown (may be an external signal, stimulus)balking message – message which will not be handled by the receiver classifier if it cannot be handled immediatelytimeout message

– similar to balking message although sender classifier is willing to wait for handling the operation for a specified period of time

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Sequence Diagrams – advanced conceptsSlide13

Creating and destroying objects:„create” stereotype message – results in creation of an object, which is situated below the primary existing classifiers, corresponding with the time of its creation

„destroy” stereotype message – results in destruction of an object

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Sequence Diagrams – advanced conceptsSlide14

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Sequence Diagrams – advanced concepts

<<Destroy>> message

<<Create>> messageSlide15

Guard condition – a criterion connected with the message, on fulfillment of which depends the execution of a specified operation.

If a condition referring to a certain message is not met the operation indicated by the message is not executed. Conditions are placed in square brackets before the message nameRealization of a message can be conditioned by more than one condition

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Sequence Diagrams – advanced conceptsSlide16

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Sequence Diagrams – advanced concepts

Guarding conditionSlide17

alt

– alternativeopt – optionbreak

– interruption

loop

– iteration

neg

– improper functionalitypar

- concurrency

critical

–

critical region

assert

– formulaconsider

– significanceignore – insignificancestricte

– strict order

seq

– weak order

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Sequence Diagrams – advanced concepts

Combined fragment

– is a logically consistent area of interaction, a part of

a

sequence diagram characterized by specific properties defined by the interaction operator

Interaction operator

– specifies the functionality realized by the combined fragment

Interaction operators:Slide18

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Sequence Diagrams – advanced concepts

Selected, most common operators:

alternative

(alt)

– means a possibility to choose only one of all presented interaction operands within the combined fragment, depending on the condition assigned to the operand

option

(opt ) – means that the operand within the combined fragment will occur or will be omitted, depending on the condition

interruption

(break)

–

is a abbreviated form of

alt

with only one defined operand and when the combined fragment is executed other interactions are ignorediteration (loop)

– means repeating the operand a specified number of timesSlide19

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Sequence Diagrams – advanced conceptsSlide20

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Sequence Diagrams – advanced conceptsSlide21

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Sequence Diagrams – advanced conceptsSlide22

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Sequence Diagrams – advanced conceptsSlide23

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Sequence Diagrams – advanced conceptsInteraction occurrence

– is a reference to a linked interaction diagram, placed within the base diagram

Interaction occurrences are especially useful in case of extensive sequence diagrams, which refer to other diagrams defined earlier

Interaction occurrence can be invoked either by a message or by time factorSlide24

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Sequence Diagrams – advanced concepts

Interaction occurrenceSlide25

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Building a sequence diagram

Analysis of a selected use case and its scenarios

Identification of classifiers taking part in the interaction

Development of conceptual sequence diagram including (identified classifiers, messages and execution specifications)

Development of a generic sequence diagram on the basis of the conceptual diagram by adding advanced concepts like: different message types, conditions, combined fragments, interaction occurrences

Optional development of instance sequence diagrams for a selected generic diagramSlide26

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Additional information and examplesUML

Sequence

Diagrams: Guidelines

https://

msdn.microsoft.com/en-us/library/dd409389.aspx

UML Sequence Diagrams: Referencehttps://msdn.microsoft.com/en-us/library/dd409377.aspx

Sequence Diagrams

http

://

www.uml-diagrams.org/sequence-diagrams.html

UML Sequence Diagrams Examples

http://www.uml-diagrams.org/sequence-diagrams-examples.html