INFORMATION SYSTEM PLANNING AND DEVELOPMENT

PRESENTED BY……VIVEK

SARITHAUSHA

RAVALITEJASWI

SMRUTHIRAMYA

SYSTEM DEVLOPMENT LIFE CYCLE(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’s development project and assesses the project’stechnical feasibility : determines if the hardware,

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

economic feasibility : determines if the project is an acceptable financial risk and if the organization can afford the expense and time needed to complete the project

behavioral feasibility : addresses the human issues of the project

SDLC (continued …)

Systems Analysis (Step 2)the examination of the business

problem that the organization plans to solve with information systems

produces the following informationstrengths 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 interfaceshardware, software, databases,

telecommunications, personnel, and procedureshow these components are integrated

local systems design : what the system will doPhysical systems design : how the system will

perform its functions

SDLC

Programming (Step 4)the translation of the design

specifications into computer codestructured programming techniques :

improve the logical flow of the program by decomposing the computer code into modules, which are sections of code

sequence structuredecision structureloop structure

SDLC

Testing (Step 5)checks to see if the computer code

will produce the expected and desired results under certain conditions

syntax errors : misspelled word or a misplaced comma

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

SDLC Implementation (Step 6)

the process of converting from the old system to the new system

four major conversion strategiesparallel conversion : the old and new systems

operate simultaneously for a period of timedirect 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

SDLC

Operation (Step 7)the new systems will operate for a period

of time, until it no longer meets its objectives

Maintenance (Step 8)debugging the programupdating the system to accommodate

changes in business conditionsadd new functionality to the system

INFORMATION SYSTEM PLANNING

I/S starts with gaining a holistic perspective 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 OF THE ORGANIZATION

The I/S Strategic plan…

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

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 that

enables users,applications, and databases to be 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 the Systems development

Two main problems with the SDLCTime consumingUser requirements change over timeExpensive

Different Methods

PrototypingJoint Application DesignRapid application development

(RAD)ICASE ToolsObject Oriented Development

Prototyping

Prototyping is an information-gathering technique

Prototypes are useful in seeking user reactions, suggestions, innovations, and revision plans

Prototype Advantages

Potential for changing the system early in its development

Opportunity to stop development on an unworkable system

Possibility of developing a system that closely addresses users' needs and expectations

Prototype Disadvantages

Managing the prototyping process is difficult because of its iterative nature and it is time consuming

It can largely replace analysis and design stages.

Joint Application Design

It is a group-based method for collecting user requirements and creating system designs.

JAD- Advantages

The group process involves more users in the development process.

Easier implementation of the new system.

Low training costs.

JAD- Disadvantages

Difficult to get all users to JAD meeting

It has all problems caused by any group process.

Rapid Application Development (RAD)

Rapid application development is a systems development that includes a method of development as well as software tools to rapidly produce a high quality system.

RAD Phases

There are three broad phases to RAD:Requirements planningRAD design workshopImplementation

Requirements Planning Phase

Users and analysts meet to identify objectives of the application or system

Oriented toward solving business problems

RAD Design Workshop

Design and refine phaseUse group decision support systems to

help users agree on designsProgrammers and analysts can build and

show visual representations of the designs and workflow to users

Users respond to actual working prototypes

Analysts refine designed modules based on user responses

Implementation Phase

As the systems are built and refined, the new systems or partial systems are tested and introduced to the organization

When creating new systems, there is no need to run old systems in parallel

RAD - Advantages

Active involvement of users in the development process.

Reduces development costCreate applications that are easier

to maintain and modify

Using RAD Within the SDLC

RAD is very powerful when used within the SDLC

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

Disadvantages of RAD

It produces system with limited functionality and flexibility for change

Therefore system may not be able to respond to changing business conditions

Produce system that are not of high quality

ICASE TOOLs

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

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

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

CASE tools that provides link between upper and lower case tools are called Integrated CASE tools.

ICASE Advantages

Produce systems with a longer effective operational life

Flexible and adaptable to changing business conditions.

Have excellent documentation

ICASE Disadvantages

Produce systems which are more expensive to built and maintain.

These are difficult to use with existing system.

Why Object Oriented Development

SDLC development approaches provide specific step-by-step instructions in the form of computer programs

These 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 not with the task to be perform, but with aspects of the real world that must be modeled to perform the task.

Advantages of OO system

It produces the system that are easy to built and maintain.

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

System developed with OO approach are more flexible.

Object-oriented analysis and desing(OOA&D)

In this approach system developers identify 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 operations that

can be performed on their properties

Advatages of OOAD

It defines all relevant objects their properties(data values) and their operations(behaviours)

Here objects have relationship to meet the objective of new system

Existing object can be used for other application saving the time spent on coding

DATAFLOW ANALYSIS

Data flow analysis is known as structured analysis It performs the following activities

Defining inputs, outputs and process that are related to system

Developing a logical model of proposed system partitioning the system into different modulesDefining the process or transformations

performed on individual modulesDefining relationship b/w modules

ADVANTAGES

It helps analyst in detecting the errors at early stages

There by reducing time and cost incurred in detecting errors at later stages

Tools for performing Structured system analysis

Dataflow diagrams Illustrates logical view rather than physical view

of business processLogical view can be represented using logical

dataflow diagramsSymbols used are ROUND RECTANGLE, SQUARE,

ARROW. Data dictionary

These specify components present in structure along with structure of files displayed in data flow diagrams

System development outside the IS department

Four methods for developing system outside the information department are: END-USER DEVELOPMENT EXTERNAL ACQUISITION OF

SOFTWARE APPLICATION SERVICE PROVIDER OUTSOURCING

END-USER DEVELOPMENT

End user computingFulfilling the information

requirements of all departments.Ability of supporting adhoc query

and reporting 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 purchasing software from external vendor

Make-or-buy decisionQuality of software increasedSome 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 costVery expensive to modify

ADVANTAGES:1)Reduces initial cost of existing software2)Satisfies all business requirements of an organization

Application Service Provider(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 internal IT cost

Provides information about available products

Increase the performance level

DISADVANTAGES:

Fails to provide customized solutions to all clients

Not flexible to changes

Cannot be integrated

OUTSOURCING

It is a practice where a company purchases a product from another company

Outsources the work to external vendor

External vendor creates the software and he is paid for it

EX: ASP

ADVANTAGES AND DISADVANTAGES

Outsourcing can reduce the costThis can built the system even

when internal resources are unavailable

Organization loses control over its information system function

It results in high cost

DATABASE

A database is a structured collection of data

Databases are designed to offer an organized 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 own related data.

Limitations of File oriented approach

Data redundancy and inconsistency: Different files may have different formats and the programs may be written in different programming languages as they are developed by different programmers. Moreover, the same information may be duplicated in several places (files). For example, the address and telephone number of

a particular customer may appear in a file that consists of saving-account records and in a file that consists of checking-account records. This redundancy leads to higher storage and access cost. It may lead to data inconsistency; that is. The various copies of the same data may no longer agree.

Limitations of File oriented approach

Difficulty in accessing data: Suppose we need to access information about all the customers of a particular scheme. During the initial stages of development of the system this kind of query might not have been known, no application program would be on hand to meet it. Say we have the application program that generates list of all the customers along with the scheme names. Thus we will have to run the latter program and sort the customers of particular scheme manually, or for each query we will have to write a new application program. Clearly we can see that accessing data is not easy in these cases.

Problems with file oriented approach

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

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

Security problems: Every person should not be allowed to access the database for security purposes. Since application programs are added to the system in an ad-hoc manner, it is difficult to ensure such security 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 item being updated on one system and not on another. 

Data Redundancy is minimised :In a non-database system, the same information may be held on several 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 a validation routine. 

Advantages of the Database 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 Approach

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

Greater Complexity :For optimum use the database must be very carefully designed. If not done well, the new system 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 is lost

Database

A database is any organized collection of data.

An UNIVERSITY example

A UNIVERSITY database for maintaining information concerning students, courses, and grades in a university 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 models Relational model Network model Hierarchical model

3.Physical data modelM.G. Erechtchoukova 61

Object based logical models

Used in describing data at logical level and view level

Logical level is to make a decision regarding what data are to be stored in the 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 the relationship between those entities.

Figure shows a very simple E-R diagram with three entity sets, Figure shows a very simple E-R diagram with three entity sets, their attributes and the relationship between the 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 instances variables, methods (bodies of code) that operates on the object

Object that contains the same types of values and same methods are grouped together into classes.

Object-Oriented Databases (OODB)

Semantic Data model

It makes easier for a user to give starting description of data in an enterprise

Contain a wide variety of relations that helps to describe a real application scenario

66

Functional Data model

Is easier to define functions and call them wherever necessary to process data

67

Record based logical models

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

Each record has fixed number of fields and each field is of fixed length

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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

14.71

Network database model

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 MODELSOTHER DATABASE MODELS

Distributed data basesObject oriented data baseActive data baseParallel data baseMultimedia data baseWeb data base

Distributed Databases

Distributed

Database - A logically interrelated collection of shared data (and a description of this data), physically distributed over a computer network.

DBMS - Software system that permits the management of the distributed database and makes the distribution transparent to users.

Distributed data base

Advantages

Increase reliability and availability. Easier expansion. Improved performance  Reliable transactions Economic

Disadvantages

Complexity  Security Economics  Inexperience Difficult to maintain integrity

NORMALIZATION

Process of efficiently organizing data in databaseEliminating data redundancyReducing design flawsHow to achieve Dividing database into two or more tables Defining relationship between them

Why normalization

Normalization objective is to isolate data so that additions, deletions and modifications made in one table is applicable to rest of tables in database

NORMAL FORMS

Normal forms are applied to achieve normalized data

Normal forms are the conditions that a table should fulfill

Different types of normal formsFirst 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 KEYCOMPOSITE KEYCANDIDATE KEYSUPER KEYFOREIGN KEY

FIRST NORMAL FORM(1NF)

Each attribute must be atomicNo repeating columns within a rowNo multi-valued columns

This 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 C1 Kevin Jacobs 201 R&D Perl1 Kevin Jacobs 201 R&D Java2 Barbara Jones 224 IT Linux2 Barbara Jones 224 IT Mac3 Jake Rivera 201 R&D DB23 Jake Rivera 201 R&D Oracle3 Jake Rivera 201 R&D Java

Employee (1NF)

Emp-no name Dept-no Dept-name skills

1 Kevin jacobs 201 R&D CPerljava

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-key

attribute is dependent on the primary key attribute

PARTIAL FUCTIONAL DEPENDENCY If an attribute is not dependent on all of

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

Partial Functional Dependence

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

emp_no name dept_no dept_name skills1 Kevin Jacobs 201 R&D C1 Kevin Jacobs 201 R&D Perl1 Kevin Jacobs 201 R&D Java2 Barbara Jones 224 IT Linux2 Barbara Jones 224 IT Mac3 Jake Rivera 201 R&D DB23 Jake Rivera 201 R&D Oracle3 Jake Rivera 201 R&D Java

Employee (1NF)

SECOND NORMAL FORM(2NF)

Meet all the requirements of 1NFAll partial dependencies must be

removed by dividing the table into small tables and building relationships between them

Example of 2NF

emp_no name dept_no dept_name skills1 Kevin Jacobs 201 R&D C1 Kevin Jacobs 201 R&D Perl1 Kevin Jacobs 201 R&D Java2 Barbara Jones 224 IT Linux2 Barbara Jones 224 IT Mac3 Jake Rivera 201 R&D DB23 Jake Rivera 201 R&D Oracle3 Jake Rivera 201 R&D Java

Employee (1NF)

emp_no name dept_no dept_name1 Kevin Jacobs 201 R&D2 Barbara Jones 224 IT3 Jake Rivera 201 R&D

Employee (2NF)emp_no skills1 C1 Perl1 Java2 Linux2 Mac3 DB23 Oracle3 Java

Skills (2NF)

Third normal form(3NF)

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_name1 Kevin Jacobs 201 R&D2 Barbara Jones 224 IT3 Jake Rivera 201 R&D

Changing in Dept_no it also reflects on dept_name

Third normal form(3NF)

Meet all the requirements of 2NFRemove all transitive

dependenciesAny transitive dependencies are

moved into a smaller (subset) table.

Examples of 3NF

emp_no name dept_no dept_name1 Kevin Jacobs 201 R&D2 Barbara Jones 224 IT3 Jake Rivera 201 R&D

Employee (2NF)

emp_no name dept_no1 Kevin Jacobs 2012 Barbara Jones 2243 Jake Rivera 201

Employee (3NF)

dept_no dept_name201 R&D224 IT

Department (3NF)

Boyce-codd Normal Form(BCNF)

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

A determinant is any attribute (simple or composite) on which some other attribute 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 in order to be fourth normal form There is no multivalued dependency in the

relation There are multivalued dependency but the

attributes are dependent between themselves

The relation must also be in BCNF Fourth normal form differs from BCNF only

in that it uses multivalued dependencies

Multivalued Dependencies(MVD)

Given a relation R, let x and y be attributes of R. Then MVD denoted as xy satisfied in relation R ift1(x)=t2(x)=t3(x)=t4(x)t1(y)=t3(y) and t2(y)=t4(x) xyX Y Z tuples

a 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:ABCDAs the relation has both FDs and MVDs it is in 4NF

Fifth normal form(5NF)

Any remaining anomalies are removed