information system planning and development

7/30/2019 information system planning and development

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INFORMATION SYSTEM

PLANNING ANDDEVELOPMENT

PRESENTED BY……

VIVEK

SARITHA

USHA

RAVALITEJASWI

SMRUTHI

RAMYA



SYSTEM DEVLOPMENT LIFECYCLE(SDLC)

Go Back to a previous Stage or Stop

(1) Systems Investigation

(2) Systems Analysis

(3) Systems Design

(4) Programming

(5) Testing

(6) Implementation

(7) Operation

(8) Maintenance

An eight-stage systems

development life cycle

(SDLC)



SDLC (continued …)

Systems Investigation (Step 1)Feasibility Study determines the probability

of success of proposed system’sdevelopment project and assesses theproject’s technical feasibility : determines if the hardware,

software, and communication components can bedeveloped or acquired to solve the business problem

economic feasibility : determines if the project is anacceptable financial risk and if the organization canafford the expense and time needed to complete theproject

behavioral feasibility : addresses the human issues of theproject



SDLC (continued …)

Systems Analysis (Step 2) the examination of the business

problem that the organization plans tosolve with information systems

produces the following information

strengths and weaknesses of the

existing systemfunctions that the new systems must

have to solve the business problem

user information requirements for the

new systems



SDLC(continued …)

Systems Design (Step 3) describes how the system will accomplish the task technical design

system outputs, inputs, and user interfaces hardware, software, databases, telecommunications,

personnel, and procedures

how these components are integrated

local systems design : what the system will do Physical systems design : how the system will

perform its functions



SDLC

Programming (Step 4) the translation of the design specifications

into computer code structured programming techniques :

improve the logical flow of the program bydecomposing the computer code intomodules, which are sections of code

sequence structure decision structure loop structure



SDLC

Testing (Step 5)

checks to see if the computer codewill produce the expected anddesired results under certainconditions

syntax errors : misspelled word or amisplaced comma

logic errors : permit the program torun, but result in incorrect output



SDLC Implementation (Step 6)

the process of converting from the old system to the newsystem

four major conversion strategies parallel conversion : the old and new systems operate

simultaneously for a period of time direct conversion : the old system is cut off and the

new systems is turned on at a certain point in time pilot conversion : introduces the new system in one

part of the organization phased conversion : introduces components of the

new systems in stages



SDLCOperation (Step 7)

the new systems will operate for a

period of time, until it no longer meetsits objectives

Maintenance (Step 8)

debugging the programupdating the system to accommodate

changes in business conditions

add new functionality to the system



I/S starts with gaining a holisticperspective on what the firm aims to

achieve.System development is the entire set of

activities needed to construct an I/S to

a business problem/opportunity.I/S is the key component which begins

with the strategic plan of the

organization.



STRATEGIC PLANNING OFTHE ORGANIZATION



The I/S Strategic plan…

The I/S strategic plan is a set of long rangegoals.

The I/s strategic plan must meet 3 objectives. It must be aligned with the organizations

strategic plan.

It must be provide for an it architecture thatenables users,applications, and databases tobe seamlessly networked and integrated

By I/S we can complete project in time,

within budget, and have required funcionality



The I/S Operation plan

I/S strategic plan leads to I/S operational plan.

A typical IS operational plan contains the

following elements.MISSION

I/S ENVIRONMENT

OBJECTIVE OF THE I/SFUNCTION. CONSTRAINT OF THE I/S FUNCTION.

LONG TERM SYSTEM NEEDS.

SHORT-RANGE PLAN.



Alternative methods to theSystems development

Two main problems with the SDLC

Time consuming

User requirements change over time

Expensive



Different Methods

Prototyping

Joint Application Design

Rapid application development (RAD)

ICASE Tools

Object Oriented Development



Prototyping

Prototyping is aninformation-

gathering techniquePrototypes are

useful in seeking

user reactions,suggestions,innovations, and

revision plans



Prototype Advantages

Potential for changing the system earlyin its development

Opportunity to stop development on anunworkable system

Possibility of developing a system that

closely addresses users' needs andexpectations



Prototype Disadvantages

Managing the prototyping process isdifficult because of its iterative nature

and it is time consumingIt can largely replace analysis and

design stages.



Joint Application Design

It is a group-based method forcollecting user requirements and

creating system designs.



JAD- Advantages

The group process involves more usersin the development process.

Easier implementation of the newsystem.

Low training costs.



JAD- Disadvantages

Difficult to get all users to JAD meeting

It has all problems caused by any groupprocess.



Rapid Application Development(RAD)

Rapid application development is asystems development that includes a

method of development as well assoftware tools to rapidly produce a highquality system.



RAD Phases

There are three broad phases to RAD:

Requirements planning

RAD design workshop

Implementation



Requirements Planning Phase

Users and analysts meet to identifyobjectives of the application or system

Oriented toward solving businessproblems



RAD Design Workshop

Design and refine phase

Use group decision support systems to

help users agree on designsProgrammers and analysts can build and

show visual representations of the designsand workflow to users

Users respond to actual working prototypes

Analysts refine designed modules based onuser responses



Implementation Phase

As the systems are built and refined,the new systems or partial systems are

tested and introduced to theorganization

When creating new systems, there is no

need to run old systems in parallel



RAD - Advantages

Active involvement of users in thedevelopment process.

Reduces development cost

Create applications that are easier tomaintain and modify



Using RAD Within the SDLC

RAD is very powerful when used withinthe SDLC

It can be used as a tool to update,improve, or innovate selected portionsof the system



Disadvantages of RAD

It produces system with limitedfunctionality and flexibility for change

Therefore system may not be able torespond to changing businessconditions

Produce system that are not of highquality



ICASE TOOLs

Computer-aided software engineering toolsautomate many of the tasks in SDLC.

The tools used to automate the early stagesof SDLC is Upper case tools.

The tools used automate the later stages inthe SDLC are lower case tools

CASE tools that provides link between upperand lower case tools are called IntegratedCASE tools.



ICASE Advantages

Produce systems with a longer effectiveoperational life

Flexible and adaptable to changingbusiness conditions.

Have excellent documentation



ICASE Disadvantages

Produce systems which are moreexpensive to built and maintain.

These are difficult to use with existingsystem.



Why Object OrientedDevelopment

SDLC development approaches providespecific step-by-step instructions in the

form of computer programsThese programs usually result in system

that performs the original task but may

not be suited for handling other tasks.



Object Oriented Development

An object oriented system begins notwith the task to be perform, but with

aspects of the real world that must bemodeled to perform the task.



Advantages of OO system

It produces the system that are easy tobuilt and maintain.

Once an object is designed and tested itcan be reused in other systems.

System developed with OO approach

are more flexible.

Obj i d l i d



Object-oriented analysis anddesing(OOA&D)

In this approach system developersidentify the objects

OBJECTS: It is a fundamental elements in OOAD

It represents tangible real world entities

Ex: customer, bank account, student.

Objects have properties and operationsthat can be performed on their

properties



Advatages of OOAD

It defines all relevant objects theirproperties(data values) and their

operations(behaviours)Here objects have relationship to meet

the objective of new system

Existing object can be used for otherapplication saving the time spent oncoding



DATAFLOW ANALYSIS

Data flow analysis is known as structuredanalysis

It performs the following activitiesDefining inputs, outputs and process that are

related to system

Developing a logical model of proposed

system partitioning the system into different modules

Defining the process or transformationsperformed on individual modules

Definin relationshi b w modules



ADVANTAGES

It helps analyst in detecting the errorsat early stages

There by reducing time and costincurred in detecting errors at laterstages

T l f f i



Tools for performingStructured system analysis

Dataflow diagrams

Illustrates logical view rather than physical

view of business processLogical view can be represented using logical

dataflow diagrams

Symbols used are ROUND RECTANGLE,

SQUARE, ARROW. Data dictionary

These specify components present in structurealong with structure of files displayed in dataflow diagrams

S t d l t t id



System development outsidethe IS department

Four methods for developing systemoutside the information department are:

END-USER DEVELOPMENT EXTERNAL ACQUISITION OF SOFTWARE

APPLICATION SERVICE PROVIDER

OUTSOURCING



END-USER DEVELOPMENT

End user computing

Fulfilling the information requirements

of all departments.

Ability of supporting adhoc query andreporting languages.



ADVANTAGES:

Level of user satisfaction incresed.

DISADVANTAGES:

Fails to address the backlog problem.No procedures for recovery process.

Cannot perform data validation.

Cannot detect errors.



External Acquisition of Software

Method of developing or purchasingsoftware from external vendor

Make-or-buy decisionQuality of software increased

Some of the Factors to be followed

Cost and financial factors Graphical presentation

Security

Data management capabilities



DISADVATAGES:

Requires large number of requirementsRequires huge amount of cost

Very expensive to modify

ADVANTAGES: 1)Reduces initial cost of existing software

2)Satisfies all business requirements of anorganization

A li ti S i



Application ServiceProvider(ASP)

Method of providing applications only to

subscribed organization Applications are hosted on asp’s data

center and users can access them or

carried out through “virtual private n/w” These are not sold or licensed



ADVANTAGES:

Minimizes internalIT cost

Providesinformation aboutavailable products

Increase theperformance level

DISADVANTAGES:

Fails to providecustomized

solutions to allclients

Not flexible to

changes Cannot be

integrated



OUTSOURCING

It is a practice where acompany purchases a

product from anothercompany

Outsources the work to

external vendorExternal vendor creates the

software and he is paid for it

EX: ASP

ADVANTAGES AND



ADVANTAGES ANDDISADVANTAGES

Outsourcing can reduce the cost

This can built the system even when

internal resources are unavailable

Organization loses control over itsinformation system function

It results in high cost



DATABASE

A database is a structured collection of data

Databases are designed to offer anorganized mechanism for storing,managing and retrieving information.



File Oriented Approach

In early days,day was stored in files.

For an application,multiple files are

required to be created.

Each file stores and maintains its ownrelated data.

Limitations of File oriented



Limitations of File orientedapproach

Data redundancy and inconsistency: Different filesmay have different formats and the programs may bewritten in different programming languages as they are

developed by different programmers. Moreover, the sameinformation may be duplicated in several places (files).

For example, the address and telephone number of aparticular customer may appear in a file that consistsof saving-account records and in a file that consists of

checking-account records. This redundancy leads tohigher storage and access cost. It may lead to datainconsistency; that is. The various copies of the samedata may no longer agree.

Limitations of File oriented



Limitations of File orientedapproach

Difficulty in accessing data: Suppose we need toaccess information about all the customers of aparticular scheme. During the initial stages of

development of the system this kind of query mightnot have been known, no application program wouldbe on hand to meet it. Say we have the applicationprogram that generates list of all the customers along

with the scheme names. Thus we will have to run thelatter program and sort the customers of particularscheme manually, or for each query we will have towrite a new application program. Clearly we can seethat accessing data is not easy in these cases.

Problems with file oriented



Problems with file orientedapproach

Data isolation: Since data is scattered in various files, which might bein different formats thus, it is difficult to write a new application toretrieve appropriate data.

Integrity Problems: The data values stored in the database mustsatisfy certain types of consistency constraints. For example, thebalance of a bank account may never fall below a prescribed amount(say, Rs. 500). Developers enforce these constraints in the systemthrough hard coding these conditions. When new constraints areadded, it is difficult to change the program to enforce them.

Security problems: Every person should not be allowed to access thedatabase for security purposes. Since application programs are addedto the system in an ad-hoc manner, it is difficult to ensure suchsecurity constraints.

Advantages of the Database




Approach

Data Independence : The data is held in such a way that changes to the structure of

the database do not effect any of the programs used to access

the data.

Consistency of Data :

Each item of data is held only once therefore no danger of itembeing updated on one system and not on another.

Data Redundancy is minimised :

In a non-database system, the same information may be held onseveral files. This wastes space and makes updating more time-consuming. A database system minimizes these effects.

Integrity of Data :

The DBMS provides users with the ability to specify constraints

on data such as making a field entry essential or using avalidation routine.





Approach

Greater Security of Data :

The DBMS can ensure only authorized users are allowed access to

the data.

Centralized Control of Data :

The Database Administrator will control who has access to what

and will structure the database with the needs of the

More Information Available to Users :

Users have access to a wider range of data that was previously

held in seperate departments and sometimes on incompatible

systems. Increased Productivity :

The DBMS provides an easy to use query language that allows

users to get immediate response from their queries rather than

having to use a specialist "programmer" to write queries for them

whole department in mind

Disadvantages of the Database



Disadvantages of the Database Approach

Larger Size :More disk space is required and probably a largerand more p owerful computer

Greater Complexity :For optimum use the database must be verycarefully designed. If not done well, the newsystem may fail to satisfy anyone.

Greater Impact of System Failure :"All eggs in one basket.“

More Complex Recovery Procedures :If a system failure occurs it is vital that no data islost



Database

A database is any organized

collection of data.



An UNIVERSITY example

A UNIVERSITY database for maintaining informationconcerning students, courses, and grades in auniversity environment

We have:STUDENT file stores data on each studentCOURSE file stores data on each courseSECTION file stores data on each section of each

courseGRADE_REPORT file stores the grades that students

receive



Example of a simple database



Types of Data models1.Object based logical models

The entity-relationship models

The Object-oriented model

The semantic data model

The functional data model

2.Record based logical modelsRelational model

Network model

Hierarchical model

3.Physical data model

M.G. Erechtchoukova 61



Object based logical models

Used in describing data at logical leveland view level

Logical level is to make a decisionregarding what data are to be stored inthe database and what relationships

must exist among those data. View level describes only part of the

entire database that is to viewed by the

database user.



Entity-relationship models (ERM)

Is based on a collection of basic objects called

entities, and the relationship among these objects.

In this step, the database designer creates an entity-

relationship (E-R) diagram to show the entities for

which information needs to be stored and therelationship between those entities.



Figure shows a very simple E-R diagram with three entity sets,

their attributes and the relationship between the entity sets.

Fig: Entities, attributes and relationships in an E-R diagram



Is based on a collection of objects

Object contains values stored in instancesvariables, methods (bodies of code) thatoperates on the object

Object that contains the same types of valuesand same methods are grouped together intoclasses.

Object-Oriented Databases (OODB)



Semantic Data model

It makes easier for a user to givestarting description of data in an

enterpriseContain a wide variety of relations that

helps to describe a real application

scenario

66



Functional Data model

Is easier to define functions and callthem wherever necessary to process

data

67



Record based logical models

Named because the data is kept in theform of records (documents) of several

types

Each record has fixed number of fields

and each field is of fixed length

68

Relational database model



In the relational model, data is organized in two-dimensional

tables called relations. The tables or relations are, however,

related to each other, as we will see shortly.

Figure: An example of the relational model representing a university

Hierarchical database model



In the hierarchical model, data is organized as an inverted

tree. Each entity has only one parent but can have several

children. At the top of the hierarchy, there is one entity,which is called the root.

Figure: An example of the hierarchical model representing a university

Network database model



14.71

In the network model, the entities are organized in a graph,

in which some entities can be accessed through several paths

(Figure 14.4).

Figure 14.4 An example of the network model representing a university

OTHER DATABASE MODELS



OTHER DATABASE MODELS

Distributed data bases

Object oriented data base

Active data base

Parallel data base

Multimedia data base

Web data base



Distributed Databases



Distributed

Database - A logically interrelated

collection of shared data (and a

description of this data), physicallydistributed over a computer network .

DBMS - Software system that permits

the management of the distributeddatabase and makes the distribution

transparent to users.

Distributed data base



Distributed data base

Advantages



Advantages

Increase reliability and availability.

Easier expansion.

Improved performance

Reliable transactions

Economic

Disadvantages



Disadvantages

Complexity

Security

Economics

Inexperience

Difficult to maintain integrity



NORMALIZATION

Process of efficiently organizing data indatabase

Eliminating data redundancyReducing design flaws

How to achieve

Dividing database into two or more tables Defining relationship between them



Why normalization

Normalization objective is to isolatedata so that additions, deletions and

modifications made in one table isapplicable to rest of tables in database



NORMAL FORMS

Normal forms are applied to achievenormalized data

Normal forms are the conditions that atable should fulfill

Different types of normal



Different types of normalforms

First normal form(1NF)

Second normal form(2NF)

Third normal form(3NF)

Boyce-codd normal form(BCNF)

Fourth normal form(4NF)

Fifth normal form(5NF)



Different type of keys

PRIMARY KEY

COMPOSITE KEY

CANDIDATE KEY

SUPER KEY

FOREIGN KEY



FIRST NORMAL FORM(1NF)

Each attribute must be atomic

No repeating columns within a row

No multi-valued columnsThis disallows “attribute as collection of

tuples”

Drawback Redundancy of data



Examples of 1NF

Employee (unnormalized)

emp_no name dept_no dept_name skills1 Kevin Jacobs 201 R&D C

1 Kevin Jacobs 201 R&D Perl

1 Kevin Jacobs 201 R&D Java

2 Barbara Jones 224 IT Linux

2 Barbara Jones 224 IT Mac

3 Jake Rivera 201 R&D DB2

3 Jake Rivera 201 R&D Oracle

3 Jake Rivera 201 R&D Java

Employee (1NF)

Emp-no name Dept-no Dept-name skills

1 Kevin jacobs 201 R&D CPerl

java

2 Barbara jones 224 IT Linuxmac

3 Jake rivera 201 R&D DB2OracleJAVA



SECOND NORMAL FORM(2NF)

FUNCTIONAL DEPENDENCY:

This can be defined as every non-keyattribute is dependent on the primary keyattribute

PARTIAL FUCTIONAL DEPENDENCY

If an attribute is not dependent on all of

the keys in the relation, we say that it haspartial dependency on the key.



Partial Functional Dependence

Skills is not functionally dependent on emp_no since it is notunique to each emp_no.

emp_no name dept_no dept_name skills

1 Kevin Jacobs 201 R&D C


1 Kevin Jacobs 201 R&D Java2 Barbara Jones 224 IT Linux

2 Barbara Jones 224 IT Mac




Employee (1NF)



SECOND NORMAL FORM(2NF)

Meet all the requirements of 1NF

All partial dependencies must be

removed by dividing the table into smalltables and building relationshipsbetween them



Example of 2NF

emp_no name dept_no dept_name skills

1 Kevin Jacobs 201 R&D C


1 Kevin Jacobs 201 R&D Java

2 Barbara Jones 224 IT Linux2 Barbara Jones 224 IT Mac




Employee (1NF)

emp_no name dept_no dept_name

1 Kevin Jacobs 201 R&D

2 Barbara Jones 224 IT

3 Jake Rivera 201 R&D

Employee (2NF) emp_no skills

1 C

1 Perl

1 Java

2 Linux

2 Mac

3 DB2

3 Oracle

3 Java

Skills (2NF)




Transitive dependencies A transitive functional dependency is when changing a

non-key column , might cause any of the other non-

key columns to change

Employee (2NF)

emp_no name dept_no dept_name

1 Kevin Jacobs 201 R&D



Changing in Dept_no it also reflects on dept_name




Meet all the requirements of 2NF

Remove all transitive dependencies

Any transitive dependencies are movedinto a smaller (subset) table.



Examples of 3NF

emp_no name dept_no dept_name1 Kevin Jacobs 201 R&D



Employee (2NF)

emp_no name dept_no

1 Kevin Jacobs 201

2 Barbara Jones 224

3 Jake Rivera 201

Employee (3NF)

dept_no dept_name

201 R&D

224 IT

Department (3NF)

Boyce-codd Normal



yForm(BCNF)

BCNF is based on the concept of a determinant (left hand attribute)

A determinant is any attribute (simpleor composite) on which some otherattribute is fully functionally dependent.

A relation is in BCNF if, and only if,every determinant is a candidate key.



Examples of BCNF

Student (un normalized)

STUDENT MAJOR ADVISOR

1 chemistry P

2 Maths Q

3 Social R

4 English S

5 chemistry p

STUDENT ADVISOR

1 P

2 Q

3 R

4 S

5 P

ADVISOR MAJOR

P chemistry

Q Maths

R Social

S English



Fourth Normal Fourth

Either of these conditions must hold true inorder to be fourth normal form

There is no multivalued dependency in the relation

There are multivalued dependency but theattributes are dependent between themselves

The relation must also be in BCNF

Fourth normal form differs from BCNF only inthat it uses multivalued dependencies

Multivalued



Dependencies(MVD)

Given a relation R, let x and y beattributes of R. Then MVD denoted as

xy satisfied in relation R if t1(x)=t2(x)=t3(x)=t4(x)

t1(y)=t3(y) and t2(y)=t4(x)

x

y X Y Z tuplesa b1 c1 tuples-1

a b2 c2 tuples-2

a b1 c2 tuples-3

a b2 c1 tuples-4



Example of 4NF

B C A D tuples

b c1 a1 d1 tuples-1

b c2 a2 d2 tuples-2

b c1 a2 d2 tuples-3

MVD:BC

FD:ABCD

As the relation has both FDs and MVDs it is in 4NF



Fifth normal form(5NF)

Any remaining anomalies are removed

Documents

information system planning and development