microsoft powerpoint - 7. sdlc

7/27/2019 Microsoft PowerPoint - 7. SDLC

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Business Information System

Systems Analysis and Design : Part I

Systems Development Life Cycle


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Participants in the Systems

Development System Owners pay for the system to be built and maintained.

And, who will ultimately benefit from the systems development

project.

Users use the system to perform or support the work to becompleted.

Project Manager is responsible for coordinating all activities and

resources needed to complete a project on time.

Systems/Business analysts facilitate the development of

information systems and computer applications by bridging the

communications gap that exists between nontechnical system

owners and users and technical system designers and builders.


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Participants in the Systems

Development System Designers design the system to meet the users

requirements.

System Builders/Developers construct, test, and deliver the

system into operation. Support Personnel are the technical specialists like database and

telecommunications experts, h/w engineers etc.

IT Vendors and Consultants sell hardware, software, and services

to businesses for incorporation into their information systems.


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(SDLC)

Production and Maintenance

Conversion/Implementation/Deployment

Testing

1. Unit Testing 2. Integration Testing 3. System Testing 4. Acceptance Testing

Coding/Programming/Development

Systems Design

1. High Level Design 2. Detailed Design

System Analysis

1. Recognition of the need 2. Feasibility Study 3.Requirement Analysis


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(SDLC) Systems Analysis :

Recognition of the need

Feasibility Study Requirements Analysis


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Systems Analysis

Recognition of the need :

The change in an existing system is desired due to:

To overcome problems in an existing system. Origin of new ideas to perform specific tasks in a better way.

To take advantage of the opportunities posed by the

environment.


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Systems Analysis

Internal Reasons for Systems Change:

Expansion of the business in the form of new offices, mergers

and acquisitions

Change of business location

Diversification of business

Problems faced in the current system

Scope of improvement in existing system


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Systems Analysis

External Reasons for Systems Change:

Change in government policies

Change of vendors or change in systems of existing

vendors

Changing consumer needs and preferences

Introduction of new standard of quality

To compete with other players in the market


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Systems Analysis

Feasibility Study :

It is performed to determine whether the proposed solution is

feasible from financial, technical or organizational standpoint.

It provides Feasibility Study Document which presents

alternative solutions along with the trade-off of expected costs

and benefits and their expectations in terms of development

schedule and required resources.

After feasibility study the management takes the go/no-godecision.

It is also used to resolve the make-buy decision.


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Systems Analysis

Types of Feasibility Study :

Economic Feasibility

Technical Feasibility Organizational Feasibility

Operational Feasibility

Motivational Feasibility

Schedule Feasibility


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Systems Analysis

Requirement Analysis :

It involves studying the existing system in detail by examining

documents, work papers, procedures, observing system

operations, and interviewing key users of the system.

Which helps to identify the primary owners and users of the

system along with the existing h/w and s/w.

It also helps to define the problem, identify its causes, specify

the solution, identify the information requirements that mustbe met by the information solution.


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Systems Analysis

Requirement Analysis :

Thus, it indentifies who needs what information, where, when,

and how.

It carefully defines the objectives of the new or modified

system.

Develops the detailed description of the functions that the new

system must perform.

A system designed around a wrong set of requirements willeither have to be discarded because of poor performance or

will need to undergo major modifications.


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(SDLC) Systems Design :

Systems analysis describes what a system should do to meet

information requirements, and systems design shows how the

system will fulfill this objective.

It is the blueprint which consists all the specifications that

give the system its form and structure.

The design architecture is governed by the SRS document.


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(SDLC) Systems Design :

High Level Design: It aims to identify,

the modules that should be in the system,

the specifications of these modules,

how they interact with each other to produce the desired

results.

Detailed Design :

The internal logic of each of the modules specified in high-

level design is decided.


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(SDLC) Coding :

Translates the design of the system into software program

code.

The aim is to implement the design in the best possiblemanner.

This phase affects both Testing and Maintenance phases. A

well-written code can reduce the testing and maintenance

efforts.


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(SDLC) Testing :

It answers the question, Will the system produce the desired

results under known conditions?

The goal of testing is to uncover requirement, design andcoding errors in the program.

Testing is the major quality control measure used during

software development.


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Testing

Unit Testing :

It involves testing each program/module separately and is

often done by the programmer himself along with the coding

of the program. It is used as a means of locating the errors in the programs,

focusing on finding all the ways to make the program fail.

Once they are pinpointed, problems can be corrected.


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Testing

Integration Testing :

Once individual modules are tested, gradually these are

integrated into subsystems, which will eventually integrated

into entire system. During integration of modules, integration testing is

performed.

The goal of this testing is to detect design errors, while

focusing on testing the interconnection between modules.


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(SDLC) System Testing :

Once the system is put together, system testing is performed.

The system is tested against the system requirements to see if

all the requirements are met and the system performs asspecified by the requirements.


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Testing

Acceptance Testing :

This testing is performed to demonstrate to the client on the

real life data of the client, the operation of the system.

This testing is often done at the customers end with realworld test data in order to satisfy the customer so that he/she

accepts the system.


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Testing

Alpha testing : Alpha testing is simulated or actual operational testing by

potential users/customers or an independent test team atthe developers' site.

Alpha testing is often employed as a form ofinternalacceptance testing, before the software goes to beta testing.

Beta testing : Beta testing comes after alpha testing and can be considered

a form ofexternal user acceptance testing.

Versions of the software, known as beta versions, arereleased to a limited audience outside of the programmingteam.

The software is released to groups of people so that furthertesting can ensure the product has few faults or bugs.


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(SDLC) Conversion/Implementation/Deployment :

It is the process ofchanging from the old system to the newsystem.

Four main conversion strategies can be employed : Parallel Strategy

Direct cutover Strategy

Pilot Study Strategy

Phased approach Strategy

It requires proper training to be given to the end-users.

Also, proper documentation showing how the system worksfor both technical and end-user standpoint is finalized at thisstage.


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(SDLC) Production and Maintenance :

After the new system is installed and conversion is complete,

the system is said to be in production.

The system will be reviewed by both users and technicalspecialists to determine how well it has met the original

objectives and whether any modifications are in order.

Once the system is fine-tuned, it must be maintained while it

is in production to correct errors, meet new requirements, or

improve processing efficiency.

Maintenance involves changes in h/w, s/w, documentation or

procedures of system in production.

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