module4-system analysis & service systems-new

8/2/2019 Module4-System Analysis & Service Systems-new

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SYSTEM DEVELOPMENT

Introduction;

Fulfilling the role of system development, a no. of diff. situationsarise, which must be understood to facilitate decisions on the

approach, strategy, technology & development. The user in thebusiness 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 systemsIntegrated systems enterprise mgt

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

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

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Need for System Analysis;

System objective

System boundariesSystem importanceNature of the systemRole of the system as an interfaceParticipation of user

Understanding of resource needsAssessment feasibility

System Analysis;

Study of end-user information requirements that is needed beforthe 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 accomplishthe objectives 2


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System Analysis of the Existing System;

Understanding the existing systemUnderstanding the objectives achieved by the existinsystemKnowing whether the system is feasible in technicall& operationally

Evaluate the system for computerization & itsplacement in the total MIS design

System Analysis of a new requirements;

Definition of the system & its objectivesDevelopment of the systemInstallation of the system & testing

Operations of the systemReview & evaluation3


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STAGES INTERPERSONAL TECHNICAL

1. Analysis stage[Working with the user to determinerequirements & translate them intodesign]

More Low

2. Design stage[To develop a detailed design ofcandidate system]

Low

3. Implementation stage[Coding & testing are carried outwith user participation][Technical &Interpersonal skills converge]

Low[in the beginning]High[in the end]

More[in the beginning]Low [in the end]

4. Maintenance stage[Role of the analyst drops off,except during unanticipated

problems if develops]

More than technical[inthe beginning ]Less than technical[as

it gradually proceeds]

Less than interpersonal[inthe beginning]More than

interpersonal[as itgradually proceeds]

Stages in System analysis

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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 data

storage

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 system

All 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 Example

A 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

Diagram

A square represents an externaldata

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

Give 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 EntityTransforming Data Data

Example;

Customer ProcessCustomerorder

Order acceptance

Product data

Customer data

Customer

orderOrderacceptance

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SSADM Development process

MODULE

Requirementanalysis

Requirementspecifications

Logical systemspecifications

Physical design

STAGES

Feasibility study Feasibility analysis

InvestigationsBasic options

Definition ofrequirements

Technical optionsLogical design

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INTRODUCTION

The details of the waterfall model vary buttwo things remain constant there areboxes going from left downward to theright and there are arrow connecting eachto 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 the

system development life cycle. In order to design a good system, traditionally,

the development 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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Information needs

specifications

Analysis

Systemdesign

Mission &Goal

Process design

Testing

Implementation

Maintenance

Water fall model

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ADVANTAGES

It allows for departmentalization andmanagerial 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 is very difficult to go back and change.

Something that was not well though out inthe concept stage.

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Th RAD M d l


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The RAD Model

Rapid application development is an incremental S/W development processmodel 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 systewithin 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 process it 18


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Data Modeling;

The information flow defined as part of the business modeling phase isrefined into a set of data objects that are needed to support the business.

The characterizes (called attributes) of the each object are identified & therelationships 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, orretrieving a data object.

Application Generation;

RAD assumes the use of the 4

th

generation techniques. Rather thancreating S/W using conventional 3rd generation programming languages theRAD process works to reuse existing program components or create reusablecomponents. In all cases, automated tools are used to facilitate constructionof the S/W.

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Testing & Turnover;Since the RAD process emphasize reuse, many of the program component

have been tested. This re3dusede overall testing time. However, newcomponents must be tested & all interfaces must be fully exercised.

Advantages of RAD 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 of RAD 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 21


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PROTO TYPE

It typically involves user and developer

The developer interviews the user anddevelops an initial system using a DBMS

The user works with the proto type andsuggest changes

Process will repeats until the user ordeveloper 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 system23


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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 made24


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PROCESS REPEATS UNTILL: User is satisfied

Formal system is built by proto type

Need 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 begenerated

Helps heavily in user interaction

DIS-ADVANTAGES :

Several users involves

When the project will be finished?

Un capability of analyst

No predefined targets 25


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SPIRAL MODEL

Spiral model proposed by Boehm1. 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 model3. It provides the potential for rapid development of incremental versions of

the software4. During early iteration, the incremental release might be paper model or

prototype5. In later iterations increasingly complete versions of the engineered system

are producedSpiral 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 communication2. Planning3. Risk analysis4. Engineering

5. Construction & release6. Customer evaluation26


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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 theMIS

MIS lies in the information needs of the various personnel inthe org across all levels of the mgt

The MIS development process largely relies on the SAD as asource of the scientific development

The modern MIS largely depends on how these technologiesare blended with the main systems

The SA begins with the O/P design

The SA with its structural analysis ensures an appropriatecoverage 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 theobjectives of the MIS

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BUSINESS PROCESS REENGINEERING [BPR]


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BUSINESS PROCESS REENGINEERING [BPR]

BPR is a methodology for introducing a fundamental change inspecific 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 customersBPR combines a strategy of promoting business innovation with a strategy

of making major improvements to business processes, so that a company canBecome a much stronger & more successful competitor in the marketplace.

Restructuring & transforming a business process by a fundamentalrethinking & redesign to achieve dramatic improvements in the cost,quality, & speed.

Example; Order Mgt

Proposal Commitment ConfigurationCredit

checkingdelivery

BillingCollections29


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Duties & Responsibilities of DBA

Design of the conceptual & physicalschemas

Security & Authorization

Data availability

Recovery the data from failure

Database tuning

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Ditties & Responsibilities of DBDesigner

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

DB designer to comm. With allprospective DB users

In many cases, the designers are on the

staff of the DBA DB designers typically interact with eachpotential group of users

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Definition of System Analyst

A system analyst is the person whoselects and configures computer systemsfor an organization or business.

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

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Change AgentThe 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 notwork well and what changes we correct theproblem.

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ArchitectThe architect s primary function as liaison

between the clients abstract design requirements andcontractor detailed building plan may be compare toanalysts role as liaison between the users logicaldesign requirements in details and physical system

design.

Psychologist

The analyst plays the role of apsychologist in the way he/she reaches people,interprets their thoughts, assesses their behaviorand 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. Theanalysts roles as a motivator becomesobvious during the first few weeks after

implementation.Politician

Related to the role of motivator is that of

politician. 36


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RESPONSIBILTIES OF A SYSTEM ANALYSTAssists 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,orb) by changing an existing application system.

Investigates such problems and opportunities to determinethe feasibility of a system 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, andb) assessing the impact of the system on their organizationand on the operation of their business. Obtains roughestimates of the cost of operating and maintaining aproposed new or changed system. 37


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Assists the project manager in identifying

the resources needed to implement a newsystem:a) the cost of developing or changing thesystem,

b) the duration of a project to do so.

It analyze the costs, benefits, risks, and

return-on-investment of the proposednew system.

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Deciding whether to proceed with theimplementation.

Prepares, in consultation with users,implementers and operations

representatives, the acceptance test planfor any new or changed system.

Assists the users in preparing for theinstallation and start-up of any new systembeing implemented.

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