A&D - Object Oriented Analysis using UML

Object Oriented Analysis with
UML
Organized By: Vinay Arora
Assistant Professor, CSED, Thapar University
www.slideshare.net/aroravinay

Disclaimer

This is NOT A COPYRIGHT MATERIAL

Content has been taken mainly from the following books:
System Analysis and Design Methods By Jeffrey L Whitten & Lonnie D Bentley ,
Analysis & Design of Information Systems By James A. Senn,
System Analysis & Design By Elias M. Awad,
Modern System Analysis & Design By Jeffrey A. Hoffer, Joey F.George & Joseph
S. Valacich

Object Oriented Analysis

Object-Oriented Analysis (OOA) – An Approach used to
1. Study existing objects to see if they can be reused or adapted for
new uses
2. Define new or modified objects that will be combined with
existing objects into a useful business computing application

Object Modeling –

A Technique for Identifying objects within the systems environment
and the relationships between those objects.

UML

UNIFIED MODELING LANGUAGE (UML) – A Set of modeling
conventions that is used to specify or describe a software system in
terms of objects.

The UML does not prescribe a method for developing systems.

Only a notation that is now widely accepted as a standard for object
modeling.

Object & Attribute

Object – something that is or is capable of being seen, touched, or otherwise
sensed, and about which users store data and associate behavior.

Person, place, thing, or event
Employee, customer, instructor, student
Warehouse, office, building, room
Product, vehicle, computer, videotape

Attribute – the data that represent characteristics of interest about an object.

Object Instance – each specific person, place, thing, or event, as well as the
values for the attributes of that object.

CLASS

Behavior – the set of things that the object can do that correspond to functions
that act on the object’s data (or attributes).

In object-oriented circles, an object’s behavior is commonly referred to as a
method, operation, or service.

Encapsulation – the packaging of several items together into one unit.

CLASS – A Set of Objects that share common attributes and behavior.
Sometimes referred to as an object class.

Inheritance : –

The Concept wherein methods and/or attributes defined in an object class can be
inherited or reused by another object class.

Generalization/Specialization

Generalization/Specialization:-
A Technique wherein the attributes and behaviors that are common to several
types of object classes are grouped (or abstracted) into their own class, called a
supertype. The attributes and methods of the supertype object class are then
inherited by those object classes.
Supertype:-

An Entity that contains attributes and behaviors that are common to one or more
class subtypes.
Subtype:-
An Object Class that Inherits attributes and behaviors from a supertype class and
then may contain other attributes and behaviors that are unique to it.

UML Representation of Generalization/Specialization

Object/Class Relationship

Object/Class Relationship – A Natural business association that exists between
one or more Objects and Classes.

Multiplicity and UML Multiplicity Notations

Multiplicity – The Minimum and Maximum
number of occurrences of one Object/Class for a
single occurrence of the related Object/Class.

Aggregation

Aggregation – A Relationship in which one larger “whole” class contains one or
more smaller “parts” classes. Conversely, a smaller “part” class is part of a
“whole” larger class.

Messages

Message – Communication that occurs when one object invokes another
object’s method (behavior) to request information or some action.

Polymorphism

Polymorphism – literally meaning “many forms,” the concept that different
objects can respond to the same message in different ways.

UML Diagrams
Use-Case Model Diagrams

Static Structure Diagrams
Class diagrams
Object diagrams

Interaction Diagrams
Sequence diagrams
Collaboration diagrams

State Diagrams
State chart diagrams
Activity diagrams

Implementation Diagrams
Component diagrams
Deployment diagrams

Process of Object Modeling

• Modeling the functions of the system.

• Finding and identifying the business objects.

• Organizing the objects and identifying their relationships.

System Use Case
The following steps evolve the requirements Use-case model into an Analysis
Use-case model:

1. Identify, define, and document new actors.

2. Identify, define, and document new use cases.

3. Identify any reuse possibilities.

4. Refine the use-case model diagram (if necessary).

5. Document system analysis use-case narratives.

System Analysis Use Case

A Use Case that Documents the Interaction between the System User and the
System.

It is highly detailed in describing What Is Required but is free from most
implementation details and constraints.

Use Case Diagram TYPES –

- Abstract Use Case

- Extension Use Case

Activity Diagram

A Diagram that can be used to graphically depict the flow of a business process,
the steps of a use case, or the logic of an object behavior (method).

One or more activity diagram can be constructed for each use case (more
than one if use case is long or contains complex logic).

Solid dot represents the start of the process.

A rounded-corner rectangle represents an activity or Create Backorder
task that needs to be performed.

Arrows depict triggers that initiate activities.

A solid black bar is a synchronization bar that allows you to depict activities
that occur in parallel.

Guidelines for Constructing Activity Diagram

Start with the one Initial node as a Starting point.

Add partitions if they are relevant to your Analysis.

Add an Action for each major Step of the use case.

Add flows from each action to another action, a decision point or an end point.

Add decisions where flows diverge with alternating routes.

Add Forks and Joins where activities are performed in PARALLEL.

End with a single notation for activity FINAL.

An Example of Activity Diagram
Example:- Activity Diagram

Activity Diagram with Partitioning

Sequence Diagram
A diagram that depicts the interaction between an Actor and the System for a use
case scenario.

A Sequence diagram depicts how objects interact with each other via messages
in the execution of a use case or operation.

Components of A System Sequence Diagram:-
Actor
System
Lifelines
Activation Bars
Input Messages
Output Message
Receiver Actor
Frame

e
uenc
m Seq
S yste iagram
D

Sequence Diagram for Login Validation

Finding Potential Objects

1. Find the Potential Objects

Review each use case to Find Nouns that correspond to business entities or
events.

2. Select the Proposed Objects

NOT ALL NOUNS represent business objects.
Ask:
Is the candidate a synonym of another object?
Is the candidate outside the scope of the system?
Is the candidate a role without unique behavior, or is it an external role?
Is the candidate unclear or in need of focus?
Is the candidate an action or an attribute that describes another object?

Partial Use-Case Narrative with Nouns
Highlighted
DESCRIPTION: This use case describes the event of a member submitting a new order for SoundStage
products via the world wide web. The member selects the items they wish to purchase.
Once they have completed their shopping, the member’s demographic information as
well as their account standing will be validated. Once the products are verified as being
in stock, a packing order is sent to the distribution center for them to prepare the
shipment. For any product not in stock, a back order is created. On completion, the
member will be sent an order confirmation.
PRE-CONDITION: The individual submitting the order must be an active club member.
The member must login in to the system (provide identification) to enter an order.
TRIGGER: This use case is initiated when the member selects the option to enter a new order.
TYPICAL COURSE Actor Action System Response
OF EVENTS: Step 1: The member requests the Step 2: The system responds by displaying the
option to enter a new order. catalogue of the SoundStage products.
Step 3: The Member browses the Step 4: Once the member has completed their
available items and selects the ones selections the system retrieves from file and
they wish to purchase along with the presents the member’s demographic information
quantity. (shipping and billing addresses).
Step 5: The member verifies Step 6: For each product ordered, the system
demographic information (shipping verifies the product availability and determines
and billing addresses). If no changes an expected ship date, determines the price to be
are necessary they respond charged to the member, and determines the cost
accordingly (to continue). of the total order. If an item is not immediately
available it indicates that the product is
backordered or that it has not been released for
shipping (for pre-orders). If an item is no longer
available that is indicated also. The system then
displays a summary of the order to the member
for verification.
Step 7: The member verifies the Step 8: The system checks the status of the
order. If no changes are necessary member’s account. If satisfactory, the system
they respond accordingly (to prompts the member to select the desired
continue). payment option (to be billed later or pay
immediately with a credit card).

TED
EC
SEL S
LY E CT
NAL OBJ
FI

Selecting Objects

Is the candidate a synonym of another object?

Is the candidate outside the scope of the system?

Is the candidate a role without unique behavior, or is it an external role?

Is the candidate unclear or in need of focus?

Is the candidate an action or an attribute that describes another object?

Organizing the Objects and Identifying their
Relationships
1. Identifying Associations and Multiplicity

2. Identifying Generalization/Specialization Relationships

3. Identifying Aggregation Relationships

4. Prepare the Class Diagram

Class Diagram

Class Diagram – A Graphical depiction of a system’s Static Object
Structure, showing object classes that the system is composed of as well
as the relationships between those object classes.

Reference List

1. System Analysis and Design Methods By Jeffrey L Whitten & Lonnie D Bentley

2. Analysis & Design of Information Systems By James A. Senn

3. System Analysis & Design By Elias M. Awad

4. Modern System Analysis & Design By Jeffrey A. Hoffer, Joey F.George & Joseph S. Valacich

etc…….

A&D - Object Oriented Analysis using UML

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