System Analysis and Development module 4

8/3/2019 System Analysis and Development module 4

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SYSTEM DEVELOPMENT

Introduction;Fulfilling the role of system development, a no. of diff. situations

arise, which must be understood to facilitate decisions on the

approach, strategy, technology & development. The user in the

business org has become more literate in terms of knowledge, use of

IT & its application in the mgt of business.

The problem of meeting the changing information needs is solved bykeeping the DB, & the knowledge base at Back end. There are a variety of

systems where system analysis would be required.

Data processing systems

TPSFunctional systems

Integrated systems enterprise mgt

The role of system analyst is a, business analyst, technology expert

& a consultant, giving a solution to the business needs of theinform. Requirement.


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Need for System Analysis;

System objective

System boundariesSystem importance

Nature of the system

Role of the system as an interface

Participation of user

Understanding of resource needs

Assessment feasibility

System Analysis;

Study of end-user information requirements that is needed beforethe design of a new inform system can be completed.

System Design;SD describe what a system should do to meet the inform needs

of users. The strategy specifies how the system will accomplish

the objectives


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System Analysis of the Existing System;

Understanding the existing systemUnderstanding the objectives achieved by the existing

system

Knowing whether the system is feasible in technically

& operationally

Evaluate the system for computerization & its

placement in the total MIS design

System Analysis of a new requirements;

Definition of the system & its objectives

Development of the system

Installation of the system & testing

Operations of the system

Review & evaluation


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INTRODUCTION

The details of the waterfall model vary but two

things remain constant there are boxes goingfrom left downward to the right and there are

arrow connecting each to its succesor.

Water fall model


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DEFINITION

The water fall model is a popular version of thesystem development lifecycle model for softwareengineering.

It is often considered the classic approach to thesystem development life cycle.

In order to design a good system, traditionally, thedevelopment have used the waterfall model.

This model describes a development method that is

linear and sequential. Waterfall development has distinct goals for each

phase of development.


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System Development Model;

We have 2 models for system development

1. Waterfall model (or) Linear sequential model

2. Spiral model Waterfall Model;


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Information needs

specifications

Analysis

System

design

Mission &

Goal

Process design

Testing

Implementation

Maintenance

WaterWaterfallfall modelmodel


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ADVANTAGES

It allows for departmentalization and managerial

control.

Each phase of department proceeds in strictorder without any overlapping.


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DISADVANTAGES

It doesnt allow for much reflection or

revision.

Once an application is in the testing stage, it isvery difficult to go back and change.

Something that was not well though out in the

concept stage.


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The RAD Model

Rapid application development is an incremental S/W development process

model that emphasizes an extremely short development cycle. The RAD

model is a high-speed adaptation of the linear sequential model in whichrapid development is achieved by using component-based construction.

If the requirement are well understood & project scope is constrained,

the RAD process enables a development team to create a fully functional system

within very short time period.

The RAD approach encompasses the following phases;

Business modelingThe information flow among businesses function is molded in a way that

answers the following questions:

1. What information drives the business processes/

2. What information is generated?

3. Who generates it?

4. where does the information go?5. Who rocess it


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Data Modeling;The information flow defined as part of the business modeling phase is

refined into a set of data objects that are needed to support the business.

The characterizes (called attributes) of the each object are identified & the

relationships b/w these objects defined

Process modeling;The data objects defined in the data modeling phase are transformed to

achieve the information flow necessary to implement a business function.Processing description are created for adding, modifying, deleting, or

retrieving a data object.

Application Generation;

RAD assumes the use of the 4th

generation techniques. Rather thancreating S/W using conventional 3rd generation programming languages the

RAD process works to reuse existing program components or create reusable

components. In all cases, automated tools are used to facilitate construction

of the S/W.


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Testing & Turnover;

Since the RAD process emphasize reuse, many of the program componenthave been tested. This re3dusede overall testing time. However, new

components must be tested & all interfaces must be fully exercised.

Advantages ofRAD modelTime constraints imposed on a RAD project demand scalable scope

Each major function to be completed in less than 3 months

Each major function can be addressed by a separate RAD team & then

integrated to form a whole

Disadvantages ofRAD model RAD requires sufficient human resources to create a right number

of RAD team

RAD require developers & customers for rapid-fire activates

Not all type of applications are appropriate for RAD

RAD is not appropriate when technical risks are high


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Business modeling

Data modeling

Process modeling

Testing & Turnover

Application generation

60 90 days


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PROTO TYPE

It typically involves user and developer

The developer interviews the user and develops an

initial system using a DBMS

The user works with the proto type and suggest

changes

Process will repeats until the user or developer is

satisfied


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Steps in system development by proto type:

System development initiated

Investigate and analyze problem sufficiently to develop workable solution

Develop prototype

Put proto type into operation

Refine and modify proto type

Complete component of system


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PROCESS OF PROTO TYPE

Initial interview

MIS designer user

Build initial proto type

New version

Use proto type

Modify proto type

Request changes

Eg: Proto type of an auto-mobile-----subsequent developments made


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PROCESS REPEATS UNTILL:

User is satisfied

Formal system is built by proto typeNeed for application is removed

Process never ends

ADVANTAGES:

Accessible than SDLC

Users wills and wishes are satisfied

Designed to be modified from the starting

Using case tools and DBMS error free code can be generated

Helps heavily in user interaction

DIS-ADVANTAGES :Several users involves

When the project will be finished?

Un capability of analyst

No predefined targets


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SPIRAL MODEL

Spiral model proposed by Boehm

1. It is evolutionary S/W process model2. Spiral have couple of iterative in nature of prototyping with the controlled

& systematic aspects of the linear sequential model

3. It provides the potential for rapid development of incremental versions of

the software

4. During early iteration, the incremental release might be paper model orprototype

5. In later iterations increasingly complete versions of the engineered system

are produced

Spiral model dividing into no. of framework activities, also called task

Regions. Spiral model guiding the risk levels in the projects

Spiral model that contains six task regions;1. Customer communication

2. Planning

3. Risk analysis

4. Engineering

5. Construction & release6. Customer evaluation


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Data Flow Diagram

A graphical system model that shows all of

the main requirements for an information

system: inputs, outputs, processes and datastorage

They are primarily used in the systems

development process.

A data flow diagram is often the diagram of

choice for modern entities.


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Context Diagram

A DFD that summarizes all processing activity

within the system in single process symbol.

Describes highest level view of a systemAll external agents and all data flows into and out

of a system are shown in the diagram

The whole system is represented as one process

The data flows that pass between the externalentities and the system.


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Purpose

To identify and examine the interface between the externalentities and the system.

For ExampleA Context Data Flow Diagram for PayrollProcessing

shows a context diagram for a Payroll Processing that

interacts with 5 agents: Employee, Management,Government Agencies, Human Resources, Timekeeping.


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Symbols used in Context

DiagramA square represents an external data

source or data destination.

A Vowel indicates a internal entity or

transformation process.

A line with an arrow indicates the

direction of the flow of data.


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Guidelines for drawing a Context

Diagram

List potential external entities (people,

places). Look for entities that

G

ive data to the system without explainingthe process that creates that data

Take data from the system withoutexplaining what it does with that data

Establish what flows are sent to and from thesystem from the external entities

Draw the context diagram


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Structured systems Analysis & Design [SSAD]

Symbols;

Flow of data process of Storage of Entity

Transforming Data Data

Example;

Customer ProcessCustomer

order

Order acceptance

Product data

Customer data

Customer

order

Order

acceptance


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Computer Systems Design;

Input Design

Output Design

Processing Design Data Specifications

Procedure Design


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MIS & Systems Analysis

Systems analysis plays a central role in the development of the MIS

MIS lies in the information needs of the various personnel in the org

across all levels of the mgt

The MIS development process largely relies on the SAD as a source of

the scientific development

The modern MIS largely depends on how these technologies are

blended with the main systems

The SA begins with the O/P design

The SA with its structural analysis ensures an appropriate coverage of

the sub-systems

MIS methodology may be the conventional design of data, DB & file

approach

MIS may call for an open system design

Systematic approach in development helps in achieving the objectives

of the MIS


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BUSINESS PROCESS REENGINEERING [BPR]

BPR is a methodology for introducing a fundamental change in

specific business process & usually supported by an IS.Business Process;

A business process is a collection of activities that

--- takes one or more kinds of I/P

--- create an O/P of value to the customers

BPR combines a strategy of promoting business innovation with a strategyof making major improvements to business processes, so that a company can

Become a much stronger & more successful competitor in the marketplace.

Restructuring & transforming a business process by a fundamental

rethinking & redesign to achieve dramatic improvements in the cost,

quality, & speed.

Example; Order Mgt

Proposal Commitment ConfigurationCredit

checkingdelivery

BillingCollections


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Duties & Responsibilities of DBA

Design of the conceptual & physical

schemas

Security &A

uthorization Data availability

Recovery the data from failure

Database tuning


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Definition of System Analyst

A system analyst is the person who selects andconfigures computer systems for anorganization or business.

The analyst must understand the generalobjectives of the business, as well as whateach individual user's job requires.


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ROLES OF SYSTEM ANALYST

Change Agent

Investigator and Monitor

Architect

Psychologist

Salesperson

MotivatorPolitician


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Change Agent

The analyst may be viewed as an agent of change.

Investigator and MonitorIn defining a problem a analyst pieces

together the information gathered to determine

why the present system does not work well andwhat changes we correct the problem.


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ArchitectThe architect s primary function as liaison

between the clients abstract design requirements and

contractor detailed building plan may be compare to analysts

role as liaison between the users logical design requirements

in details and physical system design.

PsychologistThe analyst plays the role of a psychologist in

the way he/she reaches people, interprets their thoughts,

assesses their behavior and draws conclusions from these

interactions.


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SalespersonThe analyst is also playing a role as a sales

persons.

Motivator

A candidate system must be well designed

and acceptable to the user. The analysts roles as

a motivator becomes obvious during the first few

weeks after implementation.

Politician

Related to the role of motivator is that of

politician.


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RESPONSIBILTIES OF

SYSTEM ANALYST

Assists current or potential application users in identifying and describing

problems or opportunities that might be addressed either:a) by implementing a new (automated or manual) system, or

b) by changing an existing application system.

Investigates such problems and opportunities to determine the feasibility of asystem solution.

Analyzes users business requirements in detail.

Assists and guides prospective users of a proposed new or changed system in:

a) quantifying the benefits of having the system, and

b) assessing the impact of the system on their organization and on theoperation of their business. Obtains rough estimates of the cost of operatingand maintaining a proposed new or changed system.

Assists the project manager in identifying the resources needed to implementa new system:

a) the cost of developing or changing the system,

b) the duration of a project to do so.


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Deciding whether to proceed with the implementation.

Prepares, in consultation with users, implementers and

operations representatives, the acceptance test plan for

any new or changed system.

Assists the users in preparing for the installation and

start-up of any new system being implemented.


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Ditties & Responsibilities of DB Designer

Identifying the data to be stored in the DB &for choosing appropriate structures to represent& store this data

DB designer to comm. With all prospectiveDB users

In many cases, the designers are on the staff

of the DBA

DB designers typically interact with each

potential group of users

System Analysis and Development module 4

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