uml or unified modeling language

7/29/2019 UML or unified modeling language

1/71

1

UML


2/71

2

What is USE CASE diagram?

A use case diagram establish the capability of the system as a whole.

Components of use case diagram:

ActorUse case

System boundary

Relationship

Actor relationship

Semantic of the components is followed.


3/71

3

ACTOR:

What is an actor?

An actor is some one or something that must interact with the system

under development

UML notation for actor is stickman, shown below.

Customer Manager Cashier


4/71

4

ACTOR:

More about an actor:

It is role a user plays with respect to system.

Actors are not part of the system they represent anyone oranything that must interact with the system.

Actors carry out use cases and a single actor may perform more

than one use cases.

Actors are determined by observing the direct uses of the

system,


5/71

5

ACTOR:

Contd

Those are responsible for its use and maintain as well as other systems

that interact with the developed system.

An actor may

- input information to the system.

- receive information from the system.

- input to and out from the system.


6/71

6

ACTOR:

How do we find the actor?

Ask following questions to find the actors:

Who uses the system? Who installs the system?

Who Starts up the system?

What other systems use this system?

Who gets the information from the system?

Who provides information to the system?

Actor is always external to the system. They are never part of the

system to be developed.


7/71

7

ACTOR:

4-Categories of an actor:

Principle : Who uses the main system functions. Secondary : Who takes care of administration & maintenance.

External h/w : The h/w devices which are part of application

domain and must be used.

Other system: The other system with which the system must

interact.


8/71

8

ACTOR:

Note:

If newly identified actor is using a system in a same way like an

existing actor, then new actor can be dropped. If two actors use system in the same way they are same actors.


9/71

9

USE CASE:

What is USE case?

A use case is a pattern of behavior, the system exhibits

Each use case is a sequence of related transactions performed by an

actor and the system in dialogue.

USE CASE is dialogue between an actor and the system.

Examples:

Open new account Withdrawal of cash

from ATM


10/71

10

USE CASE:

More about USE CASE:

It is a snapshot of one aspect of system.

They model a dialog between actor and system. A use case typically represents a major piece of functionality

that is complete from beginning to end.

Most of the use cases are generated in initial phase, but you

find some more as you proceed.

A use case may be small or large. It captures a broad view of aprimary functionality of the system in a manner that can be

easily grasped by non technical user.


11/71

11

USE CASE:

Contd

A use case must deliver something of value to an actor.

The use cases may be decomposed into other use cases. Use cases also present a good vehicle for project planning.


12/71

12

USE CASE:

How do we find the use cases?

What functions will the actor want from the system?

Does the system store information? What actors will create, read,update. Or delete that information?

Does the system need to notify an actor about changes in its internal

state?


13/71

13

USE CASE:

Generic format for documenting the use case:

- Pre condition: If any Use case : Name of the case.

Actors : List of actors(external agents), indicating whoinitiates the use case.

Purpose : Intention of the use case.

Overview : Description.

Type : primary / secondary.

Post condition: If any Typical Course of Events:

ACTOR ACTION : Numbered actions of the actor.

SYSTEM RESPONSE : Numbered description of system responses.


14/71

14

USE CASE:

USE CASE documentation example:

The following use case describes the process of opening a new account

in the bank.

Use case :Open new account

Actors :Customer, Cashier, Manager

Purpose :Like to have new saving account.

Description :A customerarrives in the bank to open the new

account. Customer requests for the new account

form, fill the same and submits, along with theminimal deposit. At the end of complete successful

process customer receives the passbook.

Type :Primary use case.


15/71

15

Grouping USE CASES:

Those use case functionality which are directly dependent on the

system environment are placed in interface objects

Those functionality dealing with storage and handling of information

are placed in entity objects

Functionality's specific to one or few use cases and not naturally

placed in any of the other objects are placed in control objects

By performing this division we obtain a structure which helps us to

understand the system from logical view


16/71

16

SYSTEM BOUNDARY:

What is System Boundary?

It is shown as a rectangle.

It helps to identify what is external verses internal, and what theresponsibilities of the system are.

The external environment is represented only by actors.


17/71

17

RELATIONSHIP:

What is Relationship?

Relationship between use case and actor.

Communicates Relationship between two use cases

Extends

Uses

Notation used to show the relationships:

>


18/71

18

RELATIONSHIP:

Relationship between use case and actor is often referred as

communicates .

Relationship between two use cases is refereed as either uses

or extends.

USES:

- Multiple use cases share a piece of same functionality.

- This functionality is placed in a separate use case rather thandocumenting in every use case that needs it.


19/71

19

RELATIONSHIP:

Contd...

A uses relationship shows behavior that is common to one or

more use cases.

EXTENDS:

It is used to show optional behavior, which is required only

under certain condition.


20/71

20

USE CASE diagram:

Use case diagram for the shown functionality.

Balance status

report

Withdraw cash

Validation

uses

CustomerClerk

Manager

extends

ATM


21/71

21

Beginning Analysis and Design

Completion of first version of use case diagram initiates the processes

of analysis and design.

UML provides the framework to carry out the process of analysis and

design in form of set of diagrams.

Every diagram and notation used in the diagram carries the semantics.

First step towards analysis and design is to specify the flow of events.


22/71

22

Flow of Events:

A flow of events document is created for each use case.

Details about what the system must provide to the actor when the useis executed.

Typical contents

How the use case starts and ends Normal flow of events

Alternate flow of events

Exceptional flow of events

Typical Course of Events has:

Actor Action(AA)

System Response(SR)


23/71

23

Normal Flow of Events:

Forwithdrawal of cash:

1.(SR) The ATM asks the user to insert a card.

2.(AA) The user inserts a cash card.

3.(SR) The ATM accepts the card and reads its serial number. 4.(SR) The ATM requests the password.

5.(AA) The user enters 1234.

6.(SR) The ATM verifies the serial number and password with the

bank and gets the notification accordingly.

7.(SA)The ATM asks the user to select the kind of transaction.

8.(AA)User selects the withdrawal.


24/71

24


Contd...

9.(SR)The ATM asks for the amount of cash; user enters Rs. 2500/-

10.(SR)The ATM verifies that the amount of cash is within predefined

policy limits and asks the bank, to process the transaction which

eventually confirms success and returns the new account balance.

11.(SR) The ATM dispenses cash and asks the user to take it.

12.(AA) The user takes the cash.

13.(SR) The ATM asks whether the user wants to continue.

14.(AA) The user indicates no.


25/71

25


Contd...

15.(SR) The ATM prints a receipt, ejects the card and asks the user to

take them

16.(AA) The user takes the receipt and the card.

17.(SR) The ATM asks a user to insert a card.


26/71

26

Alternative Flow of Events:

For withdrawal of cash use case:

9. The ATM asks for the amount of cash; the user has change of mind

and hits the cancel.


27/71

27

Exceptional Flow of Events:

For withdrawal of cash use case:

3 Suspicious pattern of usage on the card.

10 The machine is out of cash.

11 Money gets stuck in the machine.


28/71

28

Why flow of events?

It helps in understanding the functionality of a system to be developed.

Flow of events helps in finding objects of the system to be developed.

Happens to be most important and very first step towards analysis anddesign.


29/71

29

What is Scenario?

The functionality of the use case is captured in flow of the

events.

A scenarios is one path through the flow of events for the use

case. Scenarios are developed to help identify objects, classes and

object interactions for that use case.


30/71

30

What is Interaction diagram?

Interaction diagrams are models that describe how groups of objects

collaborate in some behavior

There are 2 kinds of interaction diagrams

Sequence diagram

Collaboration diagram

Sequence diagrams are a temporal representation of objects and their

interactions

Collaboration diagrams are spatial representation of objects, links and

interrelations


31/71

31

What is sequence diagram?

Typically these diagrams capture behaviors of the single

scenario.

Shows object interaction arranged in time sequence.

They show sequence of messages among the objects.

It has two dimensions, vertical represents time & horizontal

represents objects.

Components of sequence diagram:

-objects

-object lifeline-Message

-pre/post conditions.


32/71

32

OBJECT & OBJECT LIFE LINE:

Object are represented by rectangles and name of the objects are

underlined.

Object life line are denoted as dashed lines. They are used to

model the existence of objects over time.

Name:Class


33/71

33

MESSAGES:

They are used to model the content of communication between objects.

They are used to convey information between objects and enable

objects to request services of other objects.

The message instance has a sender, receiver, and possibly other

information according to the characteristics of the request.

Messages are denoted as labeled horizontal arrows between life lines.

The sender will send the message and receiver will receive the

message.


34/71

34

MESSAGES:

Contd

May have square brackets containing a guard conditions. This is a

Boolean condition that must be satisfied to enable the message to be

sent.

May have have an asterisk followed by square brackets containing an

iteration specification. This specifies the number of times the message

is sent.

May have return list consisting of a comma -separated list of names

that designate the values of returned by the operation.

Must have a name or identifier string that represents the message.

May have parentheses containing an argument list consisting of a

comma separated list of actual parameters passed to a method.


35/71

35

:Customer :ATM :BankRequest password

Verify accountEnter the password

Account o.k.Request option

Enter option

Request amount

Enter the amountUpdate transaction

Transaction commit

Insert card

Dispense cash

Request take cashTake cash

Request continuation

Terminate

Print receipt ,eject card

Request take cardTake card

Display main screen and prompt for the card.

:TransactionCreateTransaction

Transaction

complete

Sequence diagram [for withdrawal of cash, normal flow]


36/71

36

What is Collaboration diagram?

Collaboration diagrams illustrate the interaction between the objects,

using static spatial structure.

Unlike sequence diagram the time is not explicitly represented in these

diagrams

In collaboration diagram the sequence of messages is indicated by

numbering the messages. The UML uses the decimal numbering

scheme.

In these diagrams, an actor can be displayed in order to represent the

triggering of interaction by an element external to the system.

This helps in representing the interaction, without going into the

details of user interface.


37/71

37

Components of collaboration diagram:

Named objects

Links: Links are represented by a continuous line between objects, and

indicates the exchange of messages.

Messages has following attributes:

Synchronization --thread name, step within thread.

Sequence number

Message labels : The name of the message often corresponds to an operation

defined in the class of the object that is the destination of the message.

Message names may have the arguments and return values.

*[iteration].

It uses decimal notation.

Message direction.


38/71

38

Semantics of components:

Object names identify which objects are participating and the links

show which objects collaborate

A link between two objects must exist for one object to send message

to another and vice a versa.

Messages in the collaboration diagram get transformed to more

detailed signature.

They use the decimal notation system for numbering the messages.

The direction of the message defines the sender and receiver ofthe message


39/71

39

Collaboration diagram [for withdrawal of cash, normal flow.]

1. Insert card

Enter password, Enter kind

Enter amount,

Take cash, Take card

cancel,Terminate, Continue

Display main screen

unreadable card message,

request password,

request kind, request amount,

canceled message, eject card, failure message,

dispense cash, request take cash

request continuation,

print receipt, request take card

bad account message,

bad bank account message Verify account,process transaction

Transaction succeed

Transaction failed

account o.k.

bad account,bad password,

bad bank code

Create Transaction

Transaction completeCUST-

OMER

BANK

ATMTRANSA-

CTION


40/71

40

What is Class diagram?

A class diagram shows the existence of classes and their relationshipsin the logical view of a system

UML modeling elements in class diagrams are:

Classes, their structure and behavior.

relationships components among the classes like association,aggregation, composition, dependency and inheritance

Multiplicity and navigation indicators

Role names or labels.


41/71

41

Major Types of classes:

Concrete classes

A concrete class is a class that is instantiable; that is it can have

different instances.

Only concrete classes may be leaf classes in the inheritance tree.

Abstract classes

An abstract class is a class that has no direct instance but whose

descendants classes have direct instances.

An abstract class can define the protocol for an operation without

supplying a corresponding method we call this as an abstractoperation.

An abstract operation defines the form of operation, for which each

concrete subclass should provide its own implementation.


42/71

42

RELATIONSHIP:

Association

Aggregation

Composition

Inheritance

Dependency

Instantiation


43/71

43

ASSOCIATION:

These are the most general type of relationship:

It denotes a semantic connection between two classes

It shows BI directional connection between two classes

It is a weak coupling as associated classes remain somewhat

independent of each other

Example:

CUSTOMER ATM system


44/71

44

AGGREGATION:

This is a special type of association

The association with label contains or is part of is an

aggregation

It represents has a relationship

It is used when one object logically or physically contains other

The container is called as aggregate

It has a diamond at its end

The components of aggregate can be shared with others It expresses a whole - part relationships


45/71

45

AGGREGATION:

Example:

Customer ATM card


46/71

46

COMPOSITION:

This is a strong form of aggregation

It expresses the stronger coupling between the classes

The owner is explicitly responsible for creation and deletion of

the part

Any deletion of whole is considered to cascade its part

The aggregate has a filled diamond at its end

Window Client Area


47/71

47

INHERITANCE:

The inheritance relationship helps in managing the complexity by

ordering objects within trees of classes with increasing levels of

abstraction. Notation used is solid line with arrowhead,shown below.

Generalization and specialization are points of view that are based on

inheritance hierarchies.Account

SavingAccountCurrentAccount


48/71

48

DEPENDENCY:

Dependency is semantic connection between dependent and

independent model elements.

This association is unidirectional and is shown with dotted

arrowhead line.

In the following example it shows the dependency relationshipbetween client and server.

The client avails services provided by server so it should have

semantic knowledge of server.

The server need not know about client.

Client Server


49/71

49

INSTANTIATION

This relationship is defined between parameterized class and

actual class.

Parameterized class is also referred as generic class.

A parameterized class cant have instances unless we first

instantiated it

Example:

Queue

Queue

Element


50/71

50

What is Cardinality? :

Definition:Number of instances of each class involved in the dialogue

is specified by cardinality.

Common multiplicity values:

Symbol Meaning

1 One and only one

0..1 Zero or one

MN From M to N (natural integer)

0..* From zero to any positive integer

1..* From one to any positive integer

Also thought can be given about navigability to every applicable

relationship.


51/71

51

Reaching the class diagram:

In collaboration diagram we have shown the objects, their interaction

and detailed message signature.

This information is carried forward to the class diagram.

At this point,we group the similar objects and form classes.

Messages get mapped to responsibilities for respective classes.

Find the attributes for every class.

Transform the links to appropriate relationships.

Relationship is further refined with respect to multiplicity and

navigability.

This complete procedure brings the minimal class diagram [for withdraw cashuse case, normal flow.]


52/71

52

Class diagram[for withdrawal of cash, normal flow]

Customer

Transaction

1

0..*

1

0..*ATMSystem

1..*

1..*

1..*

1..*

Bank[Branch]1

1..*

1

1..*1

11

1


53/71

53

What more to the Class Diagram?

Till this slide we have worked out the essentials of class diagram for

withdrawal of cash use case, normal flow of events.

Similar exercise required to be carried out for every scenario and

clubbed all in the class diagram.

At this point, we refine this integrated class diagram to add further finedetails. Approximate sketch for this class diagram has been shown at

the end of this module.

Refinement attributes should be updated right from sequence diagram

to class diagram.

Next few slides will take into the discussion of refinement attributes.

This process of iterative and incremental development will continue till

there is no change in two consecutive iteration.


54/71

54

Refinement attributes:

Stereotypes:

Stereotypes are part of the range of extensibility mechanism provided

by UML

It permits user to add new model element classes on top of the kernel

predefined by UML


55/71

55


Contd

Constraints:

Constraints are functional relationship between the entities and object

model. The entities include objects, classes, attributes, association,

links.

A constraint restricts the values that entities can assume.

UML doesn't specify a particular syntax for constraints, other than they

should appear between braces, so they may therefore be expressed

using natural language, pseudo code, navigation expression or

mathematical expression

UML1.2 does prefer the use of a constraint language OCL i.e. Object

Constraint Language, which is subset of UML.


56/71

56


Qualifier:

UML provides a role of constraint notation to indicate different kind of

collections that may be inherent in the analysis model

Common role constraints for multi valued roles include

{ordered} Collection is maintained in sorted manner

{bag} Collection may have multiple copies of same item.

{set} Collection may have at most one copy of given item.

Some constraints may be combined such as: {ordered set}


57/71

57


Qualifier:

Another common design scheme is to use a key value to retrieve an

item from the collection. This is called as qualified association and the

key value as qualifier.

A qualified association is the UML equivalent of a programmingconcept variously known as associative arrays, maps,dictionaries

A qualified association relates two object classes and a qualifier

The qualifier is a special attribute that reduced the effective

multiplicity of an association.

One to many and manyto many association may be qualified.


58/71

58


Check for many to many relationship, if any, normalize with qualifier

or association class.

Check for the scope forming abstract classes and template classes.

Check for helper functions.

Thought can be given for using the design patterns.


59/71

59

Refined Class diagram [for withdrawal of cash]

SavingAccount

AccountAccessor

TellerScreen

ATMScreenBankAssociates

CashierStation

person

Cash

BatchJob

NoteHelpForBankCard

ATMSystem

BankComputer

Area

BankCard

Bank[Branch]11

1..*1..*

Customer

1

0..1

1

0..1

11

Account

1

1

1

1

1..*

1

1..*

1

Transaction

11..*

11..*

Slips

CurrentAccount

Few morerelationship can be further added to the shown diagram:


60/71

60

What is state transition diagram?

A state transition diagram shows the states of a single object, the

events or the messages that cause a transition from one state to another

and the action that result from a state change.

A state transition diagram will not be created for every class in the

system.Components of State Diagram:

Start State

Stop state

State Transition


61/71

61

Semantics of every components:

State: A state is a condition during the life of an object when it

satisfies some condition, performs some action, or waits for an event.

The UML notation for a state is a rectangle with rounded corners.

Special states:There are two special states.

Start state: Each state diagram must have one and only one start

state. Notation for start state is filled solid circle.

Stop State: An object can have multiple stop states. Notation for stop

state is bulls eye.


62/71

62

Semantics of every components:

Contd...

State transition: A state transition represents a change from an

originating to a successor state.

Transition label: event name[guard condition] / action


63/71

63

State Transition Diagram [for Account class. ]

Operational

Dormant

Open

seized

transaction request[ validate ] / update()

close

no transaction / Transfer_to_Dormant_Ledger

fill_the_request_form / update()

Fraud or authorized instruction[Validate]

/ lockAccount()

matter_resolved[ validate ] / unlockAccount()

request and fill the form for new saving account[ validate ] / process

fill_the_request_form/update()

transactionStrart / Transfer_to_main_ledger ()

Note:Account can be closed from open state as well


64/71

64

More about State Diagram:

A state diagram will not be created for every class.

state diagrams are used only for those classes that exhibit interesting

behavior.

State diagrams are also useful to investigate the behavior of user

interface and control classes.

State diagram are used to show dynamics of a individual class


65/71

65

What is activity diagram?

It is a special kind of state diagram and is worked out at use case level.

These are mainly targeted towards representing internal behavior of a

a use case.

These may be thought as a kind of flowchart.

Flowcharts are normally limited to sequential process; activity

diagrams can handle parallel process.

Activity diagrams are recommended in the following situations:

Analyzing use case

Dealing with multithreaded application

Understanding workflow across many use cases.


66/71

66

Consistency Checking

Consistency checking is the process of ensuring that,information in both static view of the system(class diagram)and the dynamic view of the system(sequence and collaboration

diagram) is telling the same story.


67/71

67

What is component diagram?

COMPONENT DIAGRAM:

Component diagrams illustrate the organizations and dependencies

among software components.

A component may be

A source code component

A run time components

An executable component Dependency relationship.


68/71

68

Component Diagram[for withdrawal of cash]

policy.dll

BranchBank.dllcustomer.dll

ATM.exe

BranchBank.exe

BankServer.exe


69/71

69

What is deployment diagram?

A deployment diagram shows the relationship among software and

hardware components in the delivered system.

These diagram include nodes and connections between nodes.

Each node in deployment diagram represents some kind of

computational unit, in most cases a piece of hardware.

Connection among nodes show the communication path over which

the system will interact.

The connections may represent direct hardware coupling line RS-232

cable, Ethernet connection, they also may represent indirect coupling

such as satellite to ground communication.


70/71

70

Deployment diagram

ATM_machine

Bank_server

BranchBank_

Ethernet

Ethernet

Bank.exe

BankServer.exeATM.exe


71/71

71

THANK-U!

uml or unified modeling language

Documents