UML (Unified Modeling Language)

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UML

• The static structure defines the kinds of the objects

important to a system and to its implementation as well as

relationship among the objects.

• The dynamic behaviour defines history of the objects

over time and the communication among the objects to

accomplish task.

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UML – some notation

• Object classes are rectangles with the name at the top,

attributes in the middle section (“compartment”) and

operations in the next compartment.

• Relationships between object classes (known as

associations) are shown as lines linking objects

• Inheritance is referred to as generalisation.

– It uses an open triangular arrow head

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UML diagrams

User’s View•Use Case Diagram

Behavioral View

•Sequence Diagram

•Collaboration Diagram

•State-chart Diagram

•Activity Diagram

Structural View

• Class Diagram

•Object Diagram

Implementation View

•Component Diagram

Environmental View

• Deployment Diagram

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The use-case view

The use-case view helps you to understand and use the system. This view

looks at how actors and use cases interact. The diagrams in this view are:

– Use-case diagrams

– Sequence diagrams

– Collaboration diagrams

– Activity diagrams

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The use-case view

• This view contains a Main diagram by default. Additional

diagrams can be added throughout the analysis and design

process.

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The logical view

The logical view addresses the functional requirements of

the system. This view looks at classes and their

relationships. The diagrams in this view are:

– Class diagrams

– Statechart diagrams

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The logical view

• This view contains a Main diagram by default. Additional

diagrams can be added throughout the analysis and design

process.

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The component view

The component view addresses the software organization

of the system. This view contains information about the

software, executable and library components for the

system. This view contains only component diagrams.

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The component view

• The component view contains a Main diagram by default.

Additional diagrams can be added to this view throughout

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The deployment view

The deployment view shows the mapping of processes to hardware.

This type of diagram is most useful in a distributed architecture

environment where you might have applications and servers at

different locations. This view contains only one diagram – the

deployment diagram.

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• Use case diagrams show the interaction of

users of the system with the functionality of

the system.

• A use case is a functional component of the

system that accomplishes a specific task, and is

represented by an ellipse.

• An actor, depicted as a stickman figure, is a

user of the system performing a specific role. Actor

UseCase

Use Case Diagrams

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Types of Actors in use case diagram:

1. Primary Actors:• People who use the main system functions.

2. Secondary Actors• People that perform administration or

maintenance tasks.

3. Other systems:• The others systems with which the system must

interact.

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Use Case Diagrams

• Use case diagrams are used early in the development

process to refine the functional specifications, identify user

interface requirements, and to define the scope of the

project.

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Use-case diagrams

– Use-case diagrams present a high-level view of

system usage as viewed from an outsider’s (actor’s)

perspective.

– These diagrams show the functionality of a system or

a class and how the system interacts with the outside

world.

– Use-case diagrams can be used during analysis to

capture the system requirements and to understand

how the system should work.

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Use-case diagrams

– During the design phase, use-case diagrams specify the

behavior of the system as implemented.

– Rose automatically creates a Main use-case diagram in

the use-case view.

– There are typically many use-case diagrams in a single

model.

– Use case model represents the external view of system.

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Types of Use-case

1.Including Use Cases:

• Use cases may contain the functionality of another use

case as part of their normal processing.

• In general it is assumed that any included use case will be

called every time the basic path is run.

• An example of this is to have the execution of the use case <Card Identification> to be run as part of a use case

<Withdraw>.

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1.Including Use Cases:

•Use Cases may be included by one or more Use Case, helping

to reduce the level of duplication of functionality by factoring

out common behavior into Use Cases that are re-used many

times.

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2. Extending Use Cases

• One use case may be used to extend the behavior of

another;

• this is typically used in exceptional circumstances.

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2. Extending Use Cases

• For example, if before modifying a particular type of customer order, a user must get approval from some higher authority, then the <Get Approval> use case may optionally extend the regular <Modify Order> use case.

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Use-case Diagram

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Example:

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Extension , Specialization Of Use Cases• Extensions:

– When the user is expected to make the optional interactions or to handle an exceptional condition, then the base use case is more or less valid, but needs further extensions by way of addition or minor modifications to complete the actor’s request.

– We create a separate use case limited to the deviation sought in the original use case .

– Extension are to be designed for handling exceptional , one off request of the users.

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Extension , Specialization Of Use Cases

• Example:

In example of railway ticket booking , it is not expected

that the passenger would change the ticket choice from ‘

Chair Car ‘ to ‘Sleeper Car’. But at the very last moment ,

if the choice is changed to Sleeper Car , the use of the

extension use case will be different for ticket printing and

related process only.

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Extension , Specialization Of Use Cases

• Specialization:

– When an analysis is made of scenario , we will; come

across use case that need to be included in the system.

– In some cases, we will come across the situation where

the use case scope is common to some extent that the

preconditions and processes within the use case and

post conditions are common across all users.

– But in the same use case, we need to handle a special

scenario where most of the specifications are common

to the special case as well.

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Extension , Specialization Of Use Cases

Ticketing Book

Ticket Booking with Concession

Journey and Tariff Special conditions

PassengerExtension Specialization

Extension with

Concession in fare

Passenger from Military Services

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Use Case Diagram ExampleOn-line Registration System

Student

viewCourseSchedule

makeClassSelection

courseAvailability

checkConflicts

verifyPrereqs

«uses»

«uses»

«uses»

confirmEnrollment

Registrar

Actor

UseCase

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Use Case Diagram Example

Figure 1.9: Use Case diagram for an Automated Teller Machine (ATM) system

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Use Case Diagram Example

• This Use Case diagram shows the interactions between the

use cases and actors of an ATM system.

• In this example, the bank's customer initiates a number of

use cases: Withdraw Money, Deposit Funds, Transfer

Funds, Make Payment, View Balance, and Change PIN.

• A few of the relationships are worthy of further mention.

• The bank officer can also initiate the Change PIN use case.

• The Make Payment use case shows an arrow going to the

credit system.

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Use Case Diagram Example

• External systems may be actors and, in this case, the credit

system is shown as an actor because it is external to the

ATM system.

• The arrow going from a use case to an actor illustrates that

the use case produces some information that an actor uses.

• In this case, the Make Payment use case provides credit

card payment information to the credit system.

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Benefits Of Use Case

– Ensures complete system documentation, as all

use cases are included with model , design and

details.

– Reduce the user’s need for training and hand-

holding in learning to operate the system.

– Use system more efficiently.

– Reduce the time for system maintenance.

– Obtain user’s fast acceptance of the system.