02_UML2Fundamentals4RhapsodyPt1

8/7/2019 02_UML2Fundamentals4RhapsodyPt1

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Essentials of IBMRationalRhapsodyfor Software Engineers

UML v2.1 Fundamentals

Courtesy of IBM Corporation Academic License

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What is UML?

Unified Modeling Language

Comprehensive full life-cycle 3rd Generation modeling languageStandardized in 1997 by the OMG (Object Management Group)

Created by a consortium of 12 companies from various domains

IBM a key contributor to behavioral modeling

Incorporates state of the art Software and Systems A&D concepts

Matches the growing complexity of real-time systemsLarge scale systems, Networking, Web enabling, Data management

Extensible and configurable

Unprecedented inter-disciplinary market penetration

UML 2.1 is latest version

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UML 2 diagrams

CommunicationDiagrams

SequenceDiagrams

InteractionDiagrams

ClassDiagrams

Deployment

Diagrams

ComponentDiagrams

ObjectDiagrams

StructuralDiagrams

state chart

Diagrams

TimingDiagrams

ActivityDiagrams

BehavioralDiagrams

Use CaseDiagrams

PackageDiagramsStructure

Diagrams

InteractionDiagrams

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Use case diagram

This diagram shows what the system does and who usesit.


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Sequence diagram

Sequence Diagrams show how instances communicateover time.

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Class diagram

Class diagrams show classes and relations betweenthem.

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Object diagram

Object Diagrams show instances of classes and showwhich ones are linked to others at run time.

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Structure diagram

This diagram shows the internal structure of classes.


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state chart diagram

state charts are used when you need to wait untilsomething happens before going to a different state.

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Activity diagram

Activity diagrams are used todescribe behavior for operations,classes, or use cases. As soon

as one activity finishes, the nextone starts.

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Package diagram

A package is similar to a folder and is used to organisethe UML model elements.

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Communication diagram

This used to be known as a Collaboration Diagramand issimilar to a Sequence Diagram, but generally lesspopular.


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Component diagram

A component diagram shows how components such as

.exe, .dll, .lib, are interconnected.

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Deployment diagram

A Deployment Diagram shows how UML artifacts aredeployed onto hardware nodes.

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Timing diagram

Time

Sending::Low

Sending::High

Receving::Low

Receiving::High

Sending

ReceivingIdle

Coil Driver

Transceiver

transmit(value)

Tristate

Monitor

Initializing

Acquiring

Reporting

Idle

send(value)

send(value)

tm(bitTime)

{1 ms +/- 0.2ms}

{3 ms +/- 0.2ms}

evDone

The Timing Diagram focuses on changing conditionswithin and among objects on a linear time axis.

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Interaction overview diagram

sdsd

ref

dispatch_event

An Interaction Diagram is a mixture of an ActivityDiagram and several Sequence Diagrams.


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How does UML apply to real-time?

Real-Time UML is standard UML

Although there have been a number of calls to extend UML forthe real-time domain experience had proven this is notnecessary. Bran Selic, Communications of the ACM, Oct 1999

Real-time and embedded applications

Special concerns about quality of service (QoS)

Special concerns about low-level programming

Special concerns about safety and reliability

Real-time UML is about applying the UML to meet thespecialized concerns of the real-time and embedded

domains

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How do you describe structure using UML?

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An object is one of the common building blocks in aUML model. It can represent a system, a subsystem ora specific software class in a programming language.

Several definitions are available:An object is a real-world or conceptual thing that has

autonomy.

An object is a cohesive entity consisting of data and theoperations that act on those data.

An object is a thing that has an interface that enforcesprotection of the encapsulation of its internal structure.

What is an object ?

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What is an object ?

Every object has:

Responsibilities:

What does the object do? Why does it exist?

Attributes:

This is the internal data and can either be fixed in value orcan vary in value.

Behaviors:

These are actions performed by the object to fulfil itsresponsibilities.


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A radio

Responsibilities:

Allow the user to listen to desired radio frequency

Attributes:

Wavelength

Frequency

Volume

Behaviors:

Tune to a frequency

Store / Recall a frequency

Change volume

Switch on / off

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A digital camera

Responsibilities:

Take digital photos

Attributes:

Available Memory

Picture Resolution

Battery Level

Behaviors:

Select Resolution

Focus

Take Photo

Upload Photos

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A microwave oven

Responsibilities?

Attributes?

Behaviors?

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Objects can be

Software thingsOccupy memory at some point in time

For example, CustomerRecord, ECGSample, Window, Font

Electronic thingsOccupy physical space at some point in time

For example, Thermometer, LCDDisplay, MotionSensor, DCMotor

Mechanical thingsOccupy physical space at some point in time

For example, WingSurface, Gear, Door, HydraulicPress

Chemical thingsOccupy physical space at some point in time

For example, Battery, GasMixture, Halothane

System thingsOccupy physical space at some point in time

For example, PowerSubsystem, RobotArm, Space Shuttle


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All objects are unique even if their attributes are the sameas another.

For example, in this room, there are probably many

mobile phones, of which several might well be identical.Even if they are identical, they are all unique.

Object identity

Andysphone

Colinsphone

Iansphone

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Objects have generally two differentviews:Public view:

This is the view that can be seen fromoutside of the object.

Private view: This is the internal only view, access is

controlled and the details are hiddenfrom the outside world.

Object views

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Object interface

The Public view of an object is the interface that the object exposesto the outside world and which other objects can use to communicatewith it.

Objects contain their own attributes and generally do not allow otherobjects to directly manipulate these attributes.

If other Objects need access to the attributes, then the objectprovides public operations (known as getters and setters) tomanipulate these attributes.

This allows the freedom to change the type of the attribute without theclients knowing about it or indeed having to make any changes. Allthat is needed is to modify the getter and setter to manipulate thenew attribute type.

Getters and Setters aresometimes called AccessorsandMutators.

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Object attributes

Attributes are typedvalues holding information knownto the object, for example:

value: int

patientName: string

All objects of the same type have the same set ofattributes but different copies(hence they may havedifferent values).

Attributes are primitive in structure and behavior:

If they are rich, then they should be themselves objects.


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Object operations

Objects execute operations to implement behavior:

Operations are primitive behaviors such as:

++x

y = sin(x)^2 + cos(x)^2 z = mySensor->getValue()

Operations can manipulate the attributes, call otheroperations.

Operations can be invoked from other objects as well asfrom a state chart or activity diagram attached to theobject.

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UML class

A Class is the definitionor specificationof an object.

An object is an instanceof a class.

An object has the attributes and behaviors defined by its class.

A class can be shown on a Class Diagram in one of many ways.

On some diagrams, you might want to show just the name of the class.

Sometimes, you might want to show just the operations; other times, youmight want to show all attributes and all operations.

Attributes

Operations

Name

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UML object

As with a class, an Object (also known as an Instance)can also be shown on a Class/Object Diagram in manyways:

It is not necessaryto show everyattribute, everyoperation, visibility,

Attributevalues at aspecific

instance intime

Object name Class name

Implicitobject

Multiplicity

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Multiplicity

When showing Objects, you need to indicate how manyobjects there are.

This is done with the Multiplicity, which most of the time is1.


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Visibility defined

Attributes and Methods or Operations are featuresof a class.

Features have the visibility adornments:

+ public

Accessible by any client of the class.

# protected Accessible only from within the same class or subclasses.

- private Accessible only from within the same class.

Rather than using thesesymbols, RationalRhapsody uses moregraphical ones which areeasier to understand.

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Constructors and destructors

Every Class has a couple of special operations allowingObjects to be constructed / destroyed.

A constructor is always called when an Object is created

and generally initializes its attributes. A destructor is always called when the Object is

destroyed and ensures that any allocated resources areproperly returned.

Constructor

Destructor

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Staticandabstract operations

A static operation is shown underlined.

An abstract operation is shown in italic.

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Exercise 1

What are the attributes, operations and responsibilities ofthe following?

Solutions will be discussed in the tute session.


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Object discovery strategies

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Object discovery strategies

Identify the nouns

Services to be performed

Transactions

Physical devices

Key concepts

Persistent data

Control Element

Walking through scenarios

Experience

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Identify the nouns

Find nouns and noun phrases in the problem statement

Provides a first-cut list of potential classes and objects

Discovers:

Objects of interest

Uninteresting objects

Attributes What do Ido?

What do I

know?

What are my

responsibilities?

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Services to be performed

Service providers are usually passive servers

May provide:

Strategy

Algorithm

Creation of complex objects

Examples:

Measurement

Filter

CommandFactory


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Physical devices

Very common approach in embedded systems.

Devices are often modeled as classes and objects.

ECG Example:

HeartA/D converter

Switch

Button

Physical devices are modeled either asinterfaces to the actual hardware (actualbehavior is in the hardware, the software class

provides a means for objects to talk to it) or, lesscommonly, simulations (simulates actualhardware behavior).

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These are the fundamental abstractions in the domain.

These concepts often have no physical manifestation.

Examples:

UI Domain Window, Icon, Cursor, Tool Bar,

Robotics Task plan

Banking Account

OS Thread

Navigation Waypoint

Key concepts

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Transactions

Transactions are objects arising from the need tomanage or track the interaction of other objects.

Transaction objects may be:

Persistent: require long term storage

Volatile: disappear when the transaction completes

Examples:

Message

Command

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Persistent information

Information that must be stored for later retrieval is eitherobjects or attributes.

Examples:

A medical device must maintain an alarm history for later

reportingWaveform data must be maintained for 20s buffer to be routed

to a chart recorder

Access passwords and user IDs

Calibration constants


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Control elements

Entities that control other objects

A specific type of causal agent

Examples:

Transaction controller in database

Audio and video synchronizer

Autopilot

Clothes washer cycle controller

A Causal agent is any entitythat produces an effect or isresponsible for events orresults.

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Walking through scenarios

Scenarios consist of objects interacting in specific waysover time.

Allow testing of class and object models:Are all necessary facilities and services available?

Do the objects attributes and behaviors support itsresponsibilities?

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02_UML2Fundamentals4RhapsodyPt1