mba it unit 3 ppt
DESCRIPTION
TRANSCRIPT
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INFORMATION SYSTEM PLANNING AND DEVELOPMENT
PRESENTED BY……VIVEK
SARITHAUSHA
RAVALITEJASWI
SMRUTHIRAMYA
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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)
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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
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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
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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
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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
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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
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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
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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
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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.
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STRATEGIC PLANNING OF THE ORGANIZATION
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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
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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.
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Alternative methods to the Systems development
Two main problems with the SDLCTime consumingUser requirements change over timeExpensive
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Different Methods
PrototypingJoint Application DesignRapid application development
(RAD)ICASE ToolsObject Oriented Development
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Prototyping
Prototyping is an information-gathering technique
Prototypes are useful in seeking user reactions, suggestions, innovations, and revision plans
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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
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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.
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Joint Application Design
It is a group-based method for collecting user requirements and creating system designs.
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JAD- Advantages
The group process involves more users in the development process.
Easier implementation of the new system.
Low training costs.
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JAD- Disadvantages
Difficult to get all users to JAD meeting
It has all problems caused by any group process.
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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.
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RAD Phases
There are three broad phases to RAD:Requirements planningRAD design workshopImplementation
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Requirements Planning Phase
Users and analysts meet to identify objectives of the application or system
Oriented toward solving business problems
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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
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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
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RAD - Advantages
Active involvement of users in the development process.
Reduces development costCreate applications that are easier
to maintain and modify
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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
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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
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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.
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ICASE Advantages
Produce systems with a longer effective operational life
Flexible and adaptable to changing business conditions.
Have excellent documentation
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ICASE Disadvantages
Produce systems which are more expensive to built and maintain.
These are difficult to use with existing system.
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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.
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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.
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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.
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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
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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
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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
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ADVANTAGES
It helps analyst in detecting the errors at early stages
There by reducing time and cost incurred in detecting errors at later stages
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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
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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
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END-USER DEVELOPMENT
End user computingFulfilling the information
requirements of all departments.Ability of supporting adhoc query
and reporting languages.
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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.
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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
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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
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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
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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
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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
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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
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DATABASE
A database is a structured collection of data
Databases are designed to offer an organized mechanism for storing, managing and retrieving information.
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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.
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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.
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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.
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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.
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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.
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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
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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
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Database
A database is any organized collection of data.
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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
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Example of a simple database
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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
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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.
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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.
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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
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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)
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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
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Functional Data model
Is easier to define functions and call them wherever necessary to process data
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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
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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
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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
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OTHER DATABASE MODELSOTHER DATABASE MODELS
Distributed data basesObject oriented data baseActive data baseParallel data baseMultimedia data baseWeb data base
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Distributed Databases
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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.
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Distributed data base
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Advantages
Increase reliability and availability. Easier expansion. Improved performance Reliable transactions Economic
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Disadvantages
Complexity Security Economics Inexperience Difficult to maintain integrity
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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
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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
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NORMAL FORMS
Normal forms are applied to achieve normalized data
Normal forms are the conditions that a table should fulfill
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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)
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Different type of keys
PRIMARY KEYCOMPOSITE KEYCANDIDATE KEYSUPER KEYFOREIGN KEY
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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
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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
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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.
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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)
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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
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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)
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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
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Third normal form(3NF)
Meet all the requirements of 2NFRemove all transitive
dependenciesAny transitive dependencies are
moved into a smaller (subset) table.
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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)
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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.
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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
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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
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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
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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
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Fifth normal form(5NF)
Any remaining anomalies are removed