analyzing a system and specifying the requirements

Analyzing a system and specifying the requirements

Analyzing a system and specifying the requirements:-

frequent communication with users .

Requirements analysis is a team effort.

demands a combination of hardware software

and human factors engineering expertise as well

as skills in dealing with people.

There are two types:-

•Structured approach

•Object oriented approach

STRUCTURED APPROACH :-

• Requirements

• Design

• Implementation

• Verification

• Maintenance

REQUIREMENTS

DESIGN

IMPLEMENTATION

Verification

Maintenance

Requirements :-bridging the gap between system requirements engineering and software design.Provides software designer with a model of : -• System information

• Function• BehaviorModel can be translated to data, architectural, and component-level designs.Expect to do a little bit of design during analysis and a little bit of analysis during design.

Requirements :-

Types of Requirements - 1

Functional requirements:input/outputprocessing.error handling.

Non-functional requirements:Physical environment (equipment locations, multiple sites, etc.).Interfaces (data medium etc.).User & human factors (who are the users, their skill level etc.).

Requirements :-

Types of Requirements - 2

Non-functional requirements (continued):Performance (how well is system functioning).Documentation.Data (qualitative stuff).Resources (finding, physical space).Security (backup, firewall).Quality assurance (max. down time, MTBF, etc.).

Design:-

Plan

Architectural design

Logical design

Physical design

Implementation :- Implementation is the realization of an application, or execution of :-

plan

model

Design

specification

standard

algorithm

Verification :-

System Verifications a set of actions used to check

the correctness of any element

Dynamic verification

Static verification

There are two fundamental approaches to verification: -

Maintenance :-

Service provider expertise

Emergency response times

Update new features

OBJECT ORIENTED APPROACH :-

principles of object oriented (OO) approach is that

of abstraction, not of data structures and processes

separately but both together.

An object is a set of data structures and the methods

or operations needed to access those structures.

The key ideas of the object oriented Approach are :-

Objects

Encapsulation

Class

Inheritance

Instances and Instantiation

Methods and Messages

Objects :- In the class-based object-oriented "object" refers to a particular instance of a class .

where the object can be a combination of variables, functions, and data structures.

In relational database management, an object can be a table or column, or an association between data and a database entity.

The main purpose of object is reuse the code.

Encapsulation :-

Encapsulation is manipulate the data, and

that keeps both safe from outside interference

and misuse.

Data encapsulation led to the important

OOP concept of data hiding.

Encapsulation (continue) :-Example :-

class Account{private double accountBalance;

public withdraw();public deposit();public determineBalance();

} //class Account

Account balancedeposit

withdraw

determine Balance

Message

Message

Message

Class :-

A class is a blueprint of prototype.

Class is the implementation of an abstract data type

and so encapsulate both data and operation.

Object is run time instance of class.

Classes just sit there ,Objects do the real work.

Memory is allocated for Objects not for classes.

programming, computer programs are designed by making them out of objects that interact with one another.

here is significant diversity in object-oriented programming. most popular languages are class-based, meaning that objects are instances of classes which typically also determines their type.

Inheritance :-

Instances and Instantiation :-

In programming, instantiation is the creation of a real instance or particular realization of an abstraction or template such as a class of objects or a computer process.

Instance (computer science) :-In object-oriented programming (OOP), an instance is a concrete occurrence of any object, existing usually during the runtime of a computer program.

Formally, "instance" is synonymous with "object" as they are each a particular value (realization), and these may be called an instance object; "instance" emphasizes the distinct identity of the object. The creation of an instance is called instantiation.

Methods and Messages :-

One of the most important capabilities that a method provides is method overriding.

Method in java programming sets the behavior of class object.

For example:- area .

Methods and Messages (continue):-

Methods also provide the interface that other

classes use to access and modify the data

properties of an object.(encapsulation)

Encapsulation and overriding are the two

primary distinguishing features between

methods and procedure calls.

Methods and Messages (continue):-

Class

1.Fields2.Constructors3.methods

class Account {int accountNumber;int accountBalance;

Public Account(double account) {accountBalance=Amount;}Public int getAccountNumber() {return accountNumber; //message}Public void deposit (double account) {accountBalance=Amount;}Public int getBalancer() {return accountBalance; //message}}

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