Development of information system chap 2

1
CHAPTER 2
INFORMATION SYSTEMS
DEVELOPMENT
https://www.youtube.com/wa
tch?v=_oLKZB9jHIo&t=24s

Introduction
 Organizations use a standard set of steps, called a
systems development methodology, to develop and
support their information systems.
 It is a standard process followed in an organization to
conduct all the steps necessary to analyze, design,
implement, and maintain information systems
 Like many processes, the development of information
systems often follows a life cycle.
 The systems development life cycle (SDLC) is a common
methodology for systems development in many
organizations.
 SDLC is The series of steps used to mark the phases of
development for an information system.

Information Systems Analysis and Design:
core concepts.
Systems Analysis:
 Systems Analysis is the study of a business problem
domain for the purpose of recommending
improvements and specifying the business
requirements for the solution.
 Systems Design:
 Systems Design is the specification or construction of
a technical, computer based solution for the business
requirements identified during systems analysis.
 Systems Analysis and Design (SAD):
 Is a method used by companies to create and maintain
information systems that perform basic business

Cont.
 The main goal of SAD is to improve organizational
systems through developing or acquiring application
software that can help employees to accomplish key
business tasks more easily and efficiently.
 An application software is designed to support a
specific organizational function or process, such as
inventory management, payroll.
 The goal of application software is to turn data into
information.
 An Information System is developed by following
Software Engineering Process, which consists of
proven methodologies, techniques and tool. These
three process work together to form an organization

Cont.
 An Information System is developed by the following
Software Engineering Process

Cont.
 Methodologies are sequence of step by step
approaches that helps to develop the final product. The
methodologies incorporate techniques like, direct
observations and interviews with users.
 Techniques provide support for a wide range of tasks
including conducting interviews with users, planning
and managing the activities of a project and designing
the reports.
 Tools are computer programs, such as computer aided
software engineering (CASE) tools, that make it easy
to use specific techniques.
6

Approach to system Analysis and Design
1. Process-oriented approach
2. Data-oriented approach
3. Object-oriented approach
7

Process-oriented approach
 Traditionally, Systems Analysts, designed an
Information System based on what the system was
meant to do, such as billing or inventory control.
 The focus was on outputs and processing logic.
 Each system would contain its own files and data
storage areas
 The data in each system would match the
specifications for that system only.
 Each systems was considered ( looked at) separately
8

Cont.
 The analysis involved in creating drawings / diagrams
that show how the data moves around the system and
where it is stored in between flows.
 The problems with this approach are,
 The existence of several files of data each locked with
different applications and programs.
 many of the files in different applications contains
same data,
 updating the data becomes tedious process, it also
difficult to combine data files created for specific
applications.
9

Data Oriented approach
 This approach tends to focus on how the data should
be represented independently of where and how data
are used in the system
 A data model is produced, which describes the data
and relationships between the data.
 Business rules define how the organization deals with
the data
 Databases are designed around the subjects such as
customers, suppliers, parts. This lets to use the
databases for many different applications.
 This means that the application is independent of data
and data definitions it is called as application

Cont.
 Today, systems development focuses on systems
integration. Systems integration allows hardware
and software from different vendors to work together
in an application.
12

Object-oriented approach
 Based on objects rather than data or process
 Emphasis here is re-usability via reusable objects
and components.
 Component-based software development.
 For non-available components, developer may
 prototype needed modules,
 use an SDLC approach,
 purchase libraries of objects,
 develop ‘his’ own, etc.

Systems Development Life Cycle (SDLC
 The series of steps used to mark the phases of
development for an information system.
 It is a common methodology for systems development.
 What are the phases of the system development cycle?
3/14/2024 SA-ISB-4-1 14

3/14/2024 15
2.2. Software Development Life Cycle- Detailed
 Each phase has specific outcomes and deliverables that
feed important information to other phase.
Phase 1. Planning
Phase 2. Analysis
Phase 3. Design
Phase 4. Implementation
Phase 5. Support/Evaluation
 Review project requests
 Prioritize project requests
 Allocate resources
 Identify project
development team
 Conduct preliminary investigation
 Perform detailed analysis activities:
Study current system
Determine user requirements
Recommend solution
 Acquire hardware
and software, if
necessary
 Develop details of
system
 Develop programs, if
necessary
 Install and test new
system
 Train users
 Convert to new system
 Conduct post-
implementation system
review
 Identify errors and
enhancements
 Monitor system performance

Systems Planning and Selection
 This first phase of the systems development
life cycle deals with the process of identifying,
selecting, initiating, planning projects and
assessing project feasibility.
 Project Identification and Selection
 The first step is to identify the need for a
system, which can be the result of
 Problems in existing system or process
 New feature required in an existing system
 A new idea for which in Information System is
required
16

Cont.
 A requirement to improve efficiency in
the organization
 The need to keep up with competitors
 During this activity a senior manager, a
business group, an Information System
manager or a steering committee
identifies and assess all possible systems
development projects, which are all may
yield significant organizational benefits.
3/14/2024 SA-ISB-4-1 17

Cont.
 The need for developing information system can come
from three key sources:
 Managers and business units who want to replace or
extend and existing system in order to gain needed
information or to provide a new service to customers.
 Information Systems mangers who want to make a
system more efficient, less costly to operate or want
to move a system to a new operating environment.
 Formal planning group that want to improve an existing
system in order to help the organization meet its
corporate objectives, such as providing better
customer service.

Cont.
 The Selection Process may vary in different
organizations, but the general process is
discussed below.
 General Process of Identifying and Selection
Information Systems development Projects
 Process of identifying and selection consists
of three activities :
1. Identifying potential development projects
2. Classifying and ranking IS development
Projects
3. Selecting IS development projects
3/14/2024 SA-ISB-4-1 20

Identifying potential development projects
 This process may be performed by a key member of
top management, or a steering committee composed
of a cross section managers, or User departments,
or the development group
 Projects identified by top management have a
strategic organizational focus, by the steering
committees have a cross functional focus, by the
individual departments have a narrow, tactical
focus. The development group identifies projects
based on the ease with existing hardware and
systems.
 Hence, projects may be identified by both top-down
and bottom-up initiatives.
3/14/2024

Classifying and ranking IS development
projects:
 Done by top managers, a steering committee,
business units or the IS development group.
 The criteria commonly used to evaluate
projects are
 Value chain analysis: Extent to which activities
add greatest benefits
 Strategic alignment: Extent the projects achieves
the long term goals

Cont.
 Potential benefits: Extent to which the project
helps to improve profits, Customer service, etc.
and the duration of the benefits
 Resource availability: Amount and type of
resources required for the project
 Project size / duration: Number of individuals
and duration to complete
 Technical difficulty / risk: Level of technical
difficult to complete.
3/14/2024 SA-ISB-4-1 23

Selecting IS development Project:
 The short and long term projects most likely to
achieve the business objectives are considered.
 The factors must be considered when selecting a
project are
 Perceived needs of the organization
 Existing systems and ongoing projects
 Resource availability
 Current business conditions
 Perspective of the decision makers
 The selected project move into the second activity
called Project initiation and planning

Planning approach
Top-down planning
 Attempts to gain a broad understanding of
information system needs of the entire
organization and offers:
 Broader perspective.
 Improved integration
 Improved management support
 Better understanding
3/14/2024 SA-ISB-4-1 25

Cont.
Bottom-up planning
 Identifies IS development projects based on
solving specific operational business problems
or taking advantage of specific opportunities
 Can be faster and less costly, so may be
beneficial in certain circumstances
3/14/2024 SA-ISB-4-1 26

Feasibility Study
 Feasibility is the measure of how beneficial
or practical the development of an
information system will be to an organization
and to the customers
 Feasibility study: decides whether or not
the proposed system is worthwhile
 It is an assessment of the practically of a
proposed project.
 It is a short focused study that checks

Cont.
 If the system contributes to organizational
objectives.
 If the system can be engineered using current
technology and within budget
 If the system can be integrated with other
systems that are used

Types of Feasibility study
 Operational feasibility
 Cultural feasibility
 Technical
 Legal
 Schedule
 Economic

feasibility:
 Operational feasibility:
 is a measure of how well a solution meets
the identified system requirements to solve
the problems and take advantage of the
opportunities envisioned for the system
 Cultural feasibility:
is a measure of how people feel about a
solution and how well it will be accepted in a
given organization climate
30

Technical feasibility
 is a measure of the practicality of a specific
technical solution and the availability of
technical resources and expertise to
implement and maintain it
 A process of assessing the development
organization's ability to construct a
proposed system
Schedule feasibility
Is a measure of how reasonable the project
timetable is Focuses on estimating the start and
completion of the
project, whether it complies with the schedule and if it
deviates out of the schedule

Cont.
Legal feasibility
 Is a measure of how well a solution can be
implemented within existing legal and
contractual obligations
 Determines whether the proposed system
conflicts with legal requirements like any data
protection act or any social media law
32

Economic feasibility
 Is a measure of the cost-effectiveness of a
project or solution, and involves performing
a cost-benefit analysis of an IT investment
a process of identifying the financial
benefits and costs associated with a
development project.
 Often referred to as a cost-benefit analysis
 Project is reviewed after each SDLC phase
in order to decide whether to continue,
redirect, or kill a project

Phase 2: Systems Analysis
 System analysis is the study of a business
problem for the purpose of recommending
improvements and specifying the business
requirements for the solution. It has three
parts:
 determining requirements,
 structuring requirements and
 selecting the best alternative design
strategy.
 These steps are may be parallel and
repetitive
3/14/2024 SA-ISB-4-1 43

Traditional Methods for Gathering Requirements
 The traditional ways to get information
directly from those who have the information
is by conducting interviews, questionnaires
and direct observation. And collecting
documentation on the current system and
organizational operation in the form of
written procedures, forms, reports and
other hard copy.
 All the methods can be used to gather
requirements and build up information about
the current system.
3/14/2024 SA-ISB-4-1 45

Modern methods for gathering requirements
 The modern methods are additional techniques
to collect information about the current
system, the organizational area requesting the
new system, and what the new system should
be like: the modern methods are Joint
Application Design and Prototyping.
 These techniques reduces the time of
collecting and structuring the requirements.
 A more recent approach to system development

Systems Analysis and
Design in a Changing
47
System Design and development Methodologies
Methodologies
 Comprehensive guidelines to follow for
completing every SDLC activity
 Collection of models, tools, and techniques
Models
 Representation of an important aspect of real
world, but not same as real thing
 Abstraction used to separate out aspect
 Diagrams and charts
 Project planning and budgeting aids

48
Computer-Aided Software Engineering:
CASE Tools
 CASE tools is Automated software tools
used by systems analysts to develop
information systems
 Automate or support the drawing and
analysis of system models and provide for
the translation of system models into
application programs.
 A collection of tools used to support the
software development process
 To support or automate activities throughout
the systems development life cycle (SDLC)

Objective of CASE tools
 Improve quality of systems to be developed
 Increase speed of development and design
 Ease and improve testing process through
automated checking
 Improve integration of development
activities via common methodologies
 Improve quality and completeness of
documentation
 Helps to standardize the development
process
3/14/2024 SA-ISB-4-1 49

50
3.3. SDLC Approach
Systems development life cycle (SDLC)
 Provides overall framework for managing system
development process
Two main approaches to SDLC
 Traditional approach: structured systems
development and information engineering
 Object-oriented approach: object technologies
requires different approach to analysis, design,
and programming
 All projects use some variation of SDLC
 A more recent approach to system development
are Prototyping, Joint Application Design (JAD) and.
 Spiral Model

Prototyping Model
 Designing and building a scaled-down version of
the desired information system with the help
of CASE tools
 Requirements are converted to a working
system that is continually revised between an
analyst and users
 One main idea behind prototyping is for the
development of fast prototypes and customer
availability for feedback.
 Prototyping is a key tool that supports rapid
application development.
 RAD involves gaining user acceptance of the

Cont.
3/14/2024 SA-ISB-4-1 52
REQUI REMENTS
DETERMI NATI ON
BY CUSTOMER
PROTOTYPE
DESI GM
PROTOTYPE
I MPLEMENTATI ON
SYSTEM CONVERSI ON
PROTOTYPE
EVALUATI ON
BY CUSTOMER
SYSTEM OPERATI ON
AND MAI NTENANCE
REQUI REMENTS FOR
CORRECTI ONS, CHANGES
AND ADDI TI ONS
REQUI REMENTS
FULFI LLED ?
SYSTEM TESTS AND
ACCEPTANCE TESTS
NO
YES

Joint Application Design (JAD)
 A structured process in which users,
managers and analysts work together for
several days in a series of intensive
meetings to specify or review system
requirements.
 These techniques can support effective
information collection and structuring while
reducing the amount of time required for
analysis.
 Many companies & industries use this
technique to study the current system & to
determine business requirements

Cont.
 The primary purpose of using JAD in the
analysis phase is to collect systems
requirements simultaneously from the key
people involved with the system
 The people involved in a JAD are JAD Session
Leader, Users, Mangers, Systems Analysts,
Scribe, IS staﬀ, sponsor
 Held in a special room equipped with white
boards, audiovisual tools, overhead projector,
ﬂip charts and computer generated displays

Spiral Model
 Uses an iterative approach designed to address each
phases in development by obtaining customer comments
and change, risk analysis, and resolution.
 The spiral model typically has a ‘spiral’ for each of the
traditional development phases.
 Within a cycle, specific engineering (design,
development, etc.) can take place using any other
models, like SDLC, prototyping,..
 The Spiral Model (Barry Boehm) is a risk-centered
development model where each spiral includes major risk
activities / assessments.
 Was developed after SDLC in response to delayed risk
in SDLC
 As the SDLC, it is considered a heavy-weight, plan-
driven methodology and is highly structured.

61
Design Phase
What is the design phase?
Acquire hardware and software
Develop all details of new or
modified information system

Design Phase
 The system analyst converts the description
of recommended solution into logical and
physical designs
 Logical design involves in designing the user
interface, databases and compute processes,
irrespective of the programming languages (
Algorithms, input and output forms, reports,
table normalization)
 During the Physical design, the analyst team
decides the programming language, database
systems to be used, hardware platform,
operating systems and network environment.
62

Cont.
 The final outcome of the design phase is the
physical system specifications, presented in
the form such as a diagram or written report
ready to be turned over to programmers and
other system builders for construction.
3/14/2024 SA-ISB-4-1 63

3/14/2024 SA-ISB-4-1 64
Design Phase
What is a detailed design?
Includes several activities
Database
design
Input and
output design
Program
design
Detailed design specifications for components in proposed
solution
Sometimes called
physical design

65
Logical and physical Database Design
Logical Database Design
 Process of constructing a model of the data
used in an enterprise based on a specific data
model (e.g. relational), but independent of a
particular DBMS and other physical
considerations.
 Conceptual data model is refined and mapped on
to a logical data model.
Pearson Education © 2009

66
Physical Database Design
 Process of producing a description of the
database implementation on secondary storage.
 Describes base relations, file organizations, and
indexes used to achieve efficient access to
data. Also describes any associated integrity
constraints and security measures.
 Tailored to a specific DBMS system.
Pearson Education © 2009

Implementation Phase
 In this phase the information system is
coded, tested and installed in the
organization, and in which the information
system is systematically repaired and
improved
 This phase also includes the initial training
to the users and documentation of the
system documented throughout the life
cycle.
 During operation part, the problems faced
by the users should be solved, and changes
and enhancements (new versions) is to be
made as per the users’ desire to reflect

Convert to new system
 What is the implementation phase?
 Purpose is to construct, or build, new or modified
system and then deliver it to users
Train users
Install and test new system
Develop programs

The Processes of Coding
 The detailed specifications produced during the
design phase are translated into functional (hardware,
communications, and executable software.)
 The design must be translated into a machine-
readable form. The code generation step performs
this task.
 Different high level programming languages are used
for coding. With respect to the type of application,
the right programming language is chosen.
 Once coding is begun, the testing process can begin
and proceed in parallel. As each program module is
produced, it can be tested individually, then as a part
of a larger program, and then as part of larger
system.
 The deliverables and outcome from the coding are
the code and program documentation.

Software testing
 Software Testing is the process of executing a program
or system with the intent of finding errors.
or, it involves any activity aimed at evaluating an attribute or
capability of a program or system and determining that
it meets its required results
 Although testing is done during implementation, we
must plan for testing earlier in the project planning.
 Testing is more than just debugging. The purpose of
testing can be quality assurance, verification and
validation, or reliability estimation.
70

Cont.
 Validation(designing the right things) the high-level
requirements agreed with the customer, about whether
customer’s requirements are satisfied or not.
Validation is a much more subjective.
 Verification(designing the thing right): Verification of
a design will most often occur within a single life-cycle
activity or between two adjacent activities.eg. the
correctness of the algorithm to compute taxes deducted
from an employee’s gross income.
 Testing is an integral part in software development. It
is broadly deployed in every phase in the software
development cycle. Typically, more than 50% percent
of the development time is spent in testing.

 Software testing can be divided into: Correctness
testing, Performance testing, Reliability testing and
Security testing.
 By scope, software testing can be categorized as
follows: Unit testing, Integration testing, System
testing, Acceptance testing.
Unit testing: Each module or unit or component is tested
alone in an attempt to discover any errors that may exist
in the code.
Integration Testing: The process of bringing together all
of the modules that a program comprises for testing
purposes.
3/14/2024 SA-ISB-4-1 72

Subsystem/System Testing
 The bringing together of all the programs that a system
comprises for testing purposes.
 All results should be documented on the Test Analysis
Report, Test Problem Report and on the Test Analysis
Approval Determination. Any failed components
should be migrated back to the development phase for
rework, and the passed components should be
migrated ahead for security testing.
3/14/2024 SA-ISB-4-1 73

3/14/2024 SA-ISB-4-1 74
System test
What are the three types of tests performed
by system developers?
Verifies application
works with other
applications
Systems test
Integration Test
Unit Test
Verifies each
individual program
works by itself
Verifies all programs
in application work
together

3/14/2024 SA-ISB-4-1 75
What is training?
 Showing users
exactly how they will
use new hardware
and software in
system

What are conversion strategies?
 The process of changing old system(manual
system) to new system.

Direct conversion
 This is in all or nothing approach
 The change over is done in one operations.
 Completely replace the old system with one go
E.g. system date setting

Phased conversion
 With this strategy, implementation can be staged with
conversion to the new system taking place by degrees.
e.g. some new file may be converted and used by
employees whilst other file continue to be used on the
old system. The new is brought in stage(phase).
 If each phase is successful then the next phase is
started. Eventually, leading to the final phase when the
new system fully replaces the old system.
3/14/2024 SA-ISB-4-1 78

Pilot conversion
 With this strategy, the new system replace the old one
in one operation but only on small scale. Any errors
can be rectified or beneficial changes can be
introduced.
 For example –it might be tried out in one branch of the
company or in one location. If successful then the pilot
is extended until it eventually replaces the old system
completely
3/14/2024 SA-ISB-4-1 79

Parallel conversion
 This is considered the most secured method with both
system running in parallel over an introductory period.
 The old system remains fully operational. While the
new system come online.
 With this strategy both system are used alongside each
other, both being able to operate independently.
 If all goes well the old system is sopped and new
system carries on as the only system.
3/14/2024 SA-ISB-4-1 80

Evaluation of Information Systems continued………
Three strategies for IS evaluation;
a. Goal based evaluation-explicit goals from origin context
b. Goal free evaluation-no explicit goals are used.
Inductive and situational driven strategy
c. Criteria based evaluation-general criteria are used
methods of criteria based evaluation of IS are;
checklists heuristics, principles/quality ideals
Three steps process of IS evaluations are;
1. Intangible benefits evaluation
2. IS investment risk analysis
3. Tangible benefits evaluation
81

Development of information system chap 2

Development of information system chap 2

Recommended

Recommended

More Related Content

Similar to Development of information system chap 2

Similar to Development of information system chap 2 (20)

Recently uploaded

Recently uploaded (20)

Development of information system chap 2