- 1. PRESENTED BYINFORMATION SYSTEM VIVEKPLANNING AND
SARITHADEVELOPMENTUSHA RAVALITEJASWISMRUTHI RAMYA
2. SYSTEM DEVLOPMENT LIFE CYCLE(SDLC)(1) Systems Investigation
An eight-stage systems (2) Systems Analysis development life
cycle(3) Systems Design(SDLC)(4) Programming (5) Testing(6)
Implementation (7) Operation (8) Maintenance Go Back to a previous
Stage or Stop 3. SDLC (continued ) Systems Investigation (Step 1)
Feasibility Study determines the probabilityof success of proposed
systemsdevelopment project and assesses theprojectstechnical
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 ofthe project 4. SDLC
(continued ) Systems Analysis (Step 2) the examination of the
businessproblem that the organization plans tosolve with
information systems produces the following information strengths
and weaknesses of the existing system functions that the new
systems must have to solve the business problem user information
requirements for the new systems 5. SDLC (continued )Systems Design
(Step 3)describes how the system will accomplish the tasktechnical
design system outputs, inputs, and user interfaces hardware,
software, databases, telecommunications,personnel, and procedures
how these components are integratedlocal systems design : what the
system will doPhysical systems design : how the system will perform
its functions 6. SDLCProgramming (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
structure decision structure loop structure 7. 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 8. SDLCImplementation
(Step 6)the process of converting from the old system to the new
systemfour 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 9.
SDLC Operation (Step 7) the new systems will operate for aperiod of
time, until it no longer meetsits objectives Maintenance (Step 8)
debugging the program updating the system to accommodatechanges in
business conditions add new functionality to the system 10.
INFORMATION SYSTEMPLANNING I/S starts with gaining a
holisticperspective on what the firm aims toachieve. System
development is the entire set ofactivities needed to construct an
I/S to abusiness problem/opportunity. I/S is the key component
which beginswith the strategic plan of theorganization. 11.
STRATEGIC PLANNING OFTHE ORGANIZATION 12. The I/S Strategic planThe
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
organizationsstrategic 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, withinbudget, and have required funcionality 13. The I/S
Operation planI/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. 14.
Alternative methods to theSystems development Two main problems
with the SDLC Time consuming User requirements change over time
Expensive 15. Different Methods Prototyping Joint Application
Design Rapid application development (RAD) ICASE Tools Object
Oriented Development 16. Prototyping Prototyping is
aninformation-gathering technique Prototypes areuseful in
seekinguser reactions,suggestions,innovations, andrevision plans
17. Prototype Advantages Potential for changing the system earlyin
its development Opportunity to stop development on anunworkable
system Possibility of developing a system thatclosely addresses
users needs andexpectations 18. Prototype Disadvantages Managing
the prototyping process isdifficult because of its iterative
natureand it is time consuming It can largely replace analysis
anddesign stages. 19. Joint Application Design It is a group-based
method forcollecting user requirements andcreating system designs.
20. JAD- Advantages The group process involves more usersin the
development process. Easier implementation of the newsystem. Low
training costs. 21. JAD- Disadvantages Difficult to get all users
to JAD meeting It has all problems caused by any groupprocess. 22.
Rapid ApplicationDevelopment (RAD) Rapid application development is
asystems development that includes amethod of development as well
assoftware tools to rapidly produce a highquality system. 23. RAD
Phases There are three broad phases to RAD: Requirements planning
RAD design workshop Implementation 24. Requirements Planning Phase
Users and analysts meet to identifyobjectives of the application or
system Oriented toward solving businessproblems 25. RAD Design
Workshop Design and refine phase Use group decision support systems
tohelp users agree on designs Programmers and analysts can build
andshow visual representations of the designsand workflow to users
Users respond to actual workingprototypes Analysts refine designed
modules basedon user responses 26. Implementation Phase As the
systems are built and refined,the new systems or partial systems
aretested and introduced to theorganization When creating new
systems, there is noneed to run old systems in parallel 27. RAD -
Advantages Active involvement of users in thedevelopment process.
Reduces development cost Create applications that are easier
tomaintain and modify 28. 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 29.
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 30. 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. 31. ICASE Advantages Produce systems
with a longer effectiveoperational life Flexible and adaptable to
changingbusiness conditions. Have excellent documentation 32. ICASE
Disadvantages Produce systems which are moreexpensive to built and
maintain. These are difficult to use with existingsystem. 33. Why
Object OrientedDevelopment SDLC development approaches
providespecific step-by-step instructions in theform of computer
programs These programs usually result insystem that performs the
original taskbut may not be suited for handling othertasks. 34.
Object Oriented Development An object oriented system begins
notwith the task to be perform, but withaspects of the real world
that must bemodeled to perform the task. 35. Advantages of OO
system It produces the system that are easy tobuilt and maintain.
Once an object is designed and testedit can be reused in other
systems. System developed with OO approachare more flexible. 36.
Object-oriented analysis anddesing(OOA&D) In this approach
system developersidentify the objectsOBJECTS: It is a fundamental
elements in OOAD It represents tangible real world entitiesEx:
customer, bank account, student. Objects have properties and
operationsthat can be performed on theirproperties 37. Advatages of
OOAD It defines all relevant objects theirproperties(data values)
and theiroperations(behaviours) Here objects have relationship to
meetthe objective of new system Existing object can be used for
otherapplication saving the time spent oncoding 38. DATAFLOW
ANALYSIS Data flow analysis is known as structuredanalysis It
performs the following activities Defining inputs, outputs and
process that arerelated to system Developing a logical model of
proposedsystem partitioning the system into different modules
Defining the process or transformationsperformed on individual
modules Defining relationship b/w modules 39. ADVANTAGES It helps
analyst in detecting the errors atearly stages There by reducing
time and costincurred in detecting errors at laterstages 40. Tools
for performingStructured system analysis Dataflow diagrams
Illustrates logical view rather than physicalview of business
process Logical view can be represented using logicaldataflow
diagramsSymbols used are ROUND RECTANGLE,SQUARE, ARROW. Data
dictionary These specify components present instructure along with
structure of files displayedin data flow diagrams 41. System
development outsidethe IS departmentFour methods for developing
system outside the information department are: END-USER DEVELOPMENT
EXTERNAL ACQUISITION OFSOFTWARE APPLICATION SERVICE PROVIDER
OUTSOURCING 42. END-USER DEVELOPMENT End user computing Fulfilling
the information requirements ofall departments. Ability of
supporting adhoc query andreporting languages. 43. 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. 44. External
Acquisition of Software Method of developing or purchasingsoftware
from external vendor Make-or-buy decision Quality of software
increasedSome of the Factors to be followed Cost and financial
factors Graphical presentation Security Data management
capabilities 45. ADVANTAGES:1)Reduces initial cost of existing
software2)Satisfies all business requirements of
anorganizationDISADVATAGES:Requires large number of
requirementsRequires huge amount of costVery expensive to modify
46. Application ServiceProvider(ASP) Method of providing
applications only tosubscribed organization Applications are hosted
on asps datacenter and users can access them orcarried out through
virtual private n/w These are not sold or licensed 47.
ADVANTAGES:DISADVANTAGES: Minimizes internal Fails to provideIT
costcustomized solutions Provides to all clientsinformation about
Not flexible toavailable products changes Increase the Cannot be
integratedperformance level 48. OUTSOURCING It is a practice where
acompany purchases aproduct from anothercompany Outsources the work
toexternal vendor External vendor creates thesoftware and he is
paid for itEX: ASP 49. ADVANTAGES ANDDISADVANTAGES Outsourcing can
reduce the cost This can built the system even wheninternal
resources are unavailable Organization loses control over
itsinformation system function It results in high cost 50. DATABASE
Adatabaseis a structured collectionof data Databasesare designed to
offer anorganized mechanism for storing,managing and retrieving
information. 51. File Oriented Approach In early days,day was
stored in files. For an application,multiple files arerequired to
be created. Each file stores and maintains its ownrelated data. 52.
Limitations of File orientedapproach Data redundancy and
inconsistency: Different filesmay have different formats and the
programs may bewritten in different programming languages as they
aredeveloped 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 consists ofsaving-account records and in
a file that consists ofchecking-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. 53. Limitations of File orientedapproach
Difficulty in accessing data: Suppose we needto access information
about all the customers of aparticular scheme. During the initial
stages ofdevelopment 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 alongwith 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. 54. Problems with file orientedapproach Data isolation:
Since data is scattered in various files, which mightbe in
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 accessthe database for security purposes.
Since application programs areadded to the system in an ad-hoc
manner, it is difficult to ensure suchsecurity constraints. 55.
Advantages of the DatabaseApproach Data Independence :The data is
held in such a way that changes to the structure ofthe database do
not effect any of the programs used to accessthe 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
heldon several files. This wastes space and makes updating
moretime-consuming. A database system minimizes these effects.
Integrity of Data :The DBMS provides users with the ability to
specify constraintson data such as making a field entry essential
or using avalidation routine. 56. Advantages of the
DatabaseApproach Greater Security of Data :The DBMS can ensure only
authorized users are allowed access tothe data. Centralized Control
of Data :The Database Administrator will control who has access to
whatand 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 previouslyheld in seperate departments and
sometimes on incompatiblesystems. Increased Productivity :The DBMS
provides an easy to use query language that allowsusers to get
immediate response from their queries rather thanhaving to use a
specialist "programmer" to write queries for them whole department
in mind 57. Disadvantages of theDatabase 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 58. DatabaseA database is
any organizedcollection of data. 59. 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
eachcourseGRADE_REPORT file stores the grades that studentsreceive
60. Example of a simple database 61. Types of Data models1.Object
based logical modelsThe entity-relationship modelsThe
Object-oriented modelThe semantic data modelThe functional data
model2.Record based logical modelsRelational modelNetwork
modelHierarchical model3.Physical data model M.G. Erechtchoukova 61
62. Object based logicalmodels 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
relationshipsmust exist among those data. View level describes only
part of theentire database that is to viewed by thedatabase user.
63. Entity-relationship models (ERM)Is based on a collection of
basic objects calledentities, and the relationship among these
objects.In this step, the database designer creates an
entity-relationship (E-R) diagram to show the entities forwhich
information needs to be stored and therelationship between those
entities. 64. 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 65. Object-Oriented Databases (OODB) 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. 66. Semantic Data model
It makes easier for a user to givestarting description of data in
anenterprise Contain a wide variety of relations thathelps to
describe a real applicationscenario 66 67. Functional Data model Is
easier to define functions and callthem wherever necessary to
processdata 67 68. 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 68 69. 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 70. Hierarchical database modelIn the
hierarchical model, data is organized as an invertedtree. Each
entity has only one parent but can have severalchildren. 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 71. Network database modelIn 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 university14.71 72. OTHER
DATABASE MODELS Distributed data bases Object oriented data base
Active data base Parallel data base Multimedia data base Web data
base 73. Distributed Databases 74. DistributedDatabase -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. 75.
Distributed data base 76. Advantages Increase reliability and
availability. Easier expansion. Improved performance Reliable
transactions Economic 77. Disadvantages Complexity Security
Economics Inexperience Difficult to maintain integrity 78.
NORMALIZATION Process of efficiently organizing data indatabase
Eliminating data redundancy Reducing design flawsHow to achieve
Dividing database into two or more tables Defining relationship
between them 79. Why normalization Normalization objective is to
isolatedata so that additions, deletions andmodifications made in
one table isapplicable to rest of tables in database 80. NORMAL
FORMS Normal forms are applied to achievenormalized data Normal
forms are the conditions that atable should fulfill 81. Different
types of normal forms 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) 82. Different type
of keys PRIMARY KEY COMPOSITE KEY CANDIDATE KEY SUPER KEY FOREIGN
KEY 83. FIRST NORMAL FORM(1NF) Each attribute must be atomic No
repeating columns within a row No multi-valued columns This
disallows attribute as collection oftuples Drawback Redundancy of
data 84. Examples of 1NFEmployee (unnormalized)Emp-noname
Dept-noDept-nameskills1 Kevin jacobs 201R&DC Perl java2 Barbara
jones224IT Linux mac3 Jake rivera201R&DDB2 Oracle JAVAEmployee
(1NF)emp_no name dept_nodept_nameskills1Kevin Jacobs
201R&DC1Kevin Jacobs 201R&DPerl1Kevin Jacobs
201R&DJava2Barbara Jones224IT Linux2Barbara Jones224IT Mac3Jake
Rivera201R&DDB23Jake Rivera201R&DOracle3Jake
Rivera201R&DJava 85. SECOND NORMALFORM(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 onallofthe keys in the relation,
we say that it haspartial dependency on the key. 86. Partial
Functional Dependence Employee (1NF) emp_no namedept_no dept_name
skills 1Kevin Jacobs201 R&D C 1Kevin Jacobs201 R&D Perl
1Kevin Jacobs201 R&D Java 2Barbara Jones 224 ITLinux 2Barbara
Jones 224 ITMac 3Jake Rivera 201 R&D DB2 3Jake Rivera 201
R&D Oracle 3Jake Rivera 201 R&D JavaSkills is not
functionally dependent on emp_no since it is notunique to each
emp_no. 87. SECOND NORMALFORM(2NF) Meet all the requirements of 1NF
All partial dependencies must beremoved by dividing the table into
smalltables and building relationshipsbetween them 88. Example of
2NFEmployee (1NF) emp_no namedept_no dept_name skills 1Kevin
Jacobs201 R&D C 1Kevin Jacobs201 R&D Perl 1Kevin Jacobs201
R&D Java 2Barbara Jones 224 ITLinux 2Barbara Jones 224 ITMac
3Jake Rivera 201 R&D DB2 3Jake Rivera 201 R&D Oracle 3Jake
Rivera 201 R&D JavaSkills (2NF)Employee (2NF) emp_noskills 1
Cemp_no namedept_no dept_name 1 Perl1Kevin Jacobs201 R&D 1
Java2Barbara Jones 224 IT2 Linux3Jake Rivera 201 R&D 2 Mac 3
DB2 3 Oracle 3 Java 89. Third normal form(3NF) Transitive
dependencies A transitive functional dependency is when changing
anon-key column , might cause any of the other non-keycolumns to
change Employee (2NF) emp_no namedept_no dept_name 1Kevin Jacobs201
R&D 2Barbara Jones 224 IT 3Jake Rivera 201 R&DChanging in
Dept_no it also reflects on dept_name 90. Third normal form(3NF)
Meet all the requirements of 2NF Remove all transitive dependencies
Any transitive dependencies are movedinto a smaller (subset) table.
91. Examples of 3NFEmployee (2NF)emp_no namedept_no dept_name1Kevin
Jacobs201 R&D2Barbara Jones 224 IT3Jake Rivera 201
R&DEmployee (3NF) Department (3NF)emp_no namedept_no dept_no
dept_name1Kevin Jacobs201 201 R&D2Barbara Jones 224 224 IT3Jake
Rivera 201 92. Boyce-codd NormalForm(BCNF) BCNF is based on the
concept ofadeterminant(left hand attribute) A determinant is any
attribute (simple orcomposite) on which some otherattribute is
fully functionally dependent. A relation is in BCNF if, and only
if,every determinant is a candidate key. 93. Examples of
BCNFStudent (un normalized)STUDENTMAJOR ADVISOR1chemistry P2Maths
Q3SocialR4English S5chemistry pSTUDENT ADVISOR ADVISOR MAJOR1 P P
chemistry2 Q Q Maths3 R R Social4 S S English5 P 94. 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 95. MultivaluedDependencies(MVD) Given a
relation R, let x and y beattributes of R. Then MVD denoted asxy
satisfied in relation R if t1(x)=t2(x)=t3(x)=t4(x) t1(y)=t3(y) and
t2(y)=t4(x)X Y Z tuples xya b1c1tuples-1a b2c2tuples-2a
b1c2tuples-3a b2c1tuples-4 96. Example of 4NF B C A Dtuples b
c1a1d1 tuples-1 b c2a2d2 tuples-2 b c1a2d2 tuples-3 MVD:BC FD:ABCD
As the relation has both FDs and MVDs it is in 4NF 97. Fifth normal
form(5NF) Any remaining anomalies are removed
