Software EngineeringITCS 3155Fall 2008

Dr. Jamie PaytonDepartment of Computer ScienceUniversity of North Carolina at Charlotte

November 18, 2008

Lecture 21Detailed Design

Dynamic Modeling with UML

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Announcements

Deliverable 3 due dateNovember 25 at 11:59 pm

Deliverable 4 due dateDecember 1611:59 pm

Final examDecember 1611:30 am – 2:30 pmWoodward 130

READ: Transforming conceptual models, Ch. 11.3

33

Lecture Overview

Chapter 12Detailed design• Dynamic class models

44

Detailed Design Stages

Mid-level designSpecifying software at level of medium-size components• Compilation units or class

Their propertiesTheir relationshipsTheir interactions Essentially:• DESCRIPTR• Design patterns (later)

Low-level designActivity of filling in small details at lowest level of abstractionPAID

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Mid-level Design and Modeling

Static modelingCaptures structure of parts of software system• UML Class Diagrams

Dynamic modelingCaptures behavior (interactions) of parts of software system• UML Sequence Diagrams

Static and dynamic models are complementaryNeed both to capture design of software system

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Mid-level Design and Dynamic Modeling

Goal is to express the behavior of the system as it executes over time

Capture the interactions between individuals• Communication between individuals that exchange information to

accomplish a task

Individuals involved may be users, actors, objects (instances of classes)

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UML Interaction Diagrams

Notations for dynamic modeling of collaborations among individualsUML interaction diagrams

Sequence diagram• Shows sequence of messages passed among communicating individuals• Highlight temporal nature of communication

Communication diagram• Shows messages passed among communicating individuals• Highlights collaborations

Interaction overview diagram• Activity diagram + Sequence diagrams

Timing diagram• Shows change in state of individual over time

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Example Interaction Diagrams:Sequence Diagram

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Example Interaction Diagrams:Collaboration Diagram

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Example Interaction Diagrams:

Interaction Overview

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Example Interaction Diagrams:Timing Diagram

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UML Sequence Diagrams

Most widely used notation for describing interactionsClearly expresses message flow between individualsHighlights time ordering of interactions

13

UML Sequence Diagram Notation:Frame

Rectangle that encloses the diagram with pentagon-shaped name compartment

Name can be simple name or operation name (with params)

:User :Button

press

actionPerformed(event)toggle

:ButtonListener :Light

getState()

sd ButtonPress name compartment

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UML Sequence Diagram Notation:Lifeline

Represents a participating individual Usually an object (instance of class)

Modeled as rectangle with dashed line extending downTime is represented vertically in diagramDashed line represents individual’s existenceRectangle is labeled with lifeline identifier

Lifelineclient

:Component

supplier

create

Xdestroy

sd UseComponent

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Lifeline Creation and DestructionNew object appears at the point it is createdDestroyed object has a truncated lifeline

marked with an XPersistent objects have lifelines that run the length of the diagram

client

:Component

supplier

create

Xdestroy

sd UseComponent

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Lifeline Identifier Format

Namesimple name, or “self”• Used when interaction depicted is “owned” by the individual

SelectorExpression to select an individual from a collection• Format not specified in UML

typeNameType of the individual• Format not specified in UML

Can omit name or :typeNameBut not both!

name[selector] : typeName

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UML Sequence Diagram Notation:Message Arrows

Three typesSynchronous messagesAsynchronous messagesSynchronous message return or instance creation

:User :Button

press

actionPerformed(event)toggle

:ButtonListener :Light

getState()

sd ButtonPress

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Message Specification Format

VariableSimple name of a variable assigned a resultOptional; if omitted, so is the equals sign

nameSimple name of the message

argumentListComma-separated list of arguments in parenthesesPossible formats:• varName = paramName• paramName = argumentValue• —Optional; parentheses may appear even if omitted

Message specification may be * (any message)

variable = name argumentList

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Message Specification Examples

hellohello()msg = getMessage( helloMessage )x = sin( a/2 )x = sin( angle = a/2 )trim( result = aString )Warning

Assigning a value to a parameter and assigning a returned “out” parameter to a variable cannot be distinguishedUse variable/parameter assignments in correct order of parameters• Don’t define assignment based on names of parameters

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UML Sequence Diagram Notation:Execution Occurrence

Indicates an object is activeObject is active if one or more operations is active• Operation is executing

Process is running code• Operation is suspended

Waiting on return of control from synchronous message

:User :Button

press

actionPerformed(event)toggle

:ButtonListener :Light

getState()

sd ButtonPress

executionoccurrence

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Combined Fragments

A combined fragment is a marked part of an interaction diagram that shows

BranchingLoopsConcurrent executionOther properties

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Optional Fragment

A portion of an interaction that may be doneEquivalent to a conditional (guarded) statement• Conditional based on satisfaction of guard

A guard is a Boolean expression Placed in square brackets in UMLExamples• [isEnrolled]• [isAuthorized]• [else] is a special guard

true if every other guard is false

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Optional Fragment Example

self:PrintServer

[isCmprsd]

sd print( f : File )

f:File

opt

isCmprsd=isCompressed()

decompress()

:Printer

print(f)

Denoted by “opt” fragment operatorSingle “opt” operand is enclosed by rectangle

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Alternative Fragment

A combined fragment with mutually exclusive conditional statements

Equivalent to a case or switch statementOperator is the keyword “alt”“alt” can be applied to one or more operands

self:Light

turnOff()

:Bulb

sd toggle()

[state==on]alt

turnOn()[state==off]

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Break Fragment

A combined fragment that uses a guarded statement to determine to discontinue “typical” execution

Similar to a break statementOperator is the keyword breakOperates only on one operand

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Break Fragment Example

self:PrintServer

[isCmprsd]

sd print( f : File )

f:File

opt

isCmprsd=isCompressed()

decompress()

:Printer

print(f)

[!readable]break

print(errMsg)

readable=canRead()

stderr

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Loop Fragment

Single loop body operand that may have a guardOperator has the form loop( min, max ) [guard]

Parameters are optional• if omitted, so are the parentheses

min is a non-negative integermax is a non-negative integer • min <= max <= *• max is optional; if omitted, so is the comma

In this case, max = min

Default guard is true

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Loop Fragment Example

controller

i:Iterator

i = iterator()

isMore = hasNext()

o:Object :Collection

create

loop [isMore]o = next()

process()

isMore = hasNext()

Xdestroy

sd Iteration