ئەو دەرسە دەخوێنن کۆرسی ١ ITM3 زانکۆی پۆلی تەکنیکی دهۆک بەشی lectures (1)

1. SYSTEMS ANALYSIS
& DESIGN
lectures
2017-2018
By: Assistant Lecturer
Zhiyan A. younis
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2. System Analysis and Design -
Overview
Systems development is systematic
process which includes phases such as
planning, analysis, design, deployment,
and maintenance.
Here, we will primarily focus on −
1-Systems analysis
2-Systems design

3. Systems Analysis
• It is a process of collecting and interpreting facts,
identifying the problems, and decomposition of a
system into its components.
• System analysis is conducted for the purpose of
studying a system or its parts in order to identify
its objectives. It is a problem solving technique
that improves the system and ensures that all the
components of the system work efficiently to
accomplish their purpose.
• Analysis specifies what the system should do.

4. Systems Design
• It is a process of planning a new business system or
replacing an existing system by defining its components or
modules to satisfy the specific requirements. Before
planning, you need to understand the old system thoroughly
and determine how computers can best be used in order to
operate efficiently.
• System Design focuses on how to accomplish the
objective of the system.
• System Analysis and Design (SAD) mainly focuses on −
• Systems
• Processes
• Technology

5. What is a System?
• The word System is derived from Greek word
Systema, which means an organized
relationship between any set of components to
achieve some common cause or objective.
• A system is “an orderly grouping of
interdependent components linked together
according to a plan to achieve a specific
goal.”

6. Characteristics of a System
• Components
• Interrelated Components
• Boundary
• Purpose
• Environment
• Interfaces
• Constraints
• Input
• Output
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8. System characteristics
• A component
• an irreducible part or aggregation of parts that make
up a system, also called a subsystem
• Interrelated components
• Dependence of one subsystem on one or more
subsystems
• Boundary
• The line that marks the inside and outside of a
system and that sets off the system form its
environment
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9. System characteristics
• Purpose
• The overall goal or function of a system
• Environment
• Everything external to a system that interacts with
the system
• Interface
• Point of contact where a system meets its
environment or where subsystems meet each other.
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10. System characteristics
• Constraint
• A limit to what a system can accomplish
• Input
• Whatever a system takes from its environment in order
to fulfill its purpose
• Output
• Whatever a system returns from its environment in
order to fulfill its purpose
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11. Systems Models
• 1-Schematic Models
• A schematic model is a 2-D chart that shows
system elements and their linkages.
• Different arrows are used to show information
flow, material flow, and information feedback.

12. 2-Flow System Models
• A flow system model shows the orderly flow
of the material, energy, and information that
hold the system together.
• Program Evaluation and Review Technique
(PERT), for example, is used to abstract a real
world system in model form.

13. 3-Static System Models
• They represent one pair of relationships such
as activity–time or cost–quantity.
• The Gantt chart, for example, gives a static
picture of an activity-time relationship.

14. 4-Dynamic System Models
• Business organizations are dynamic systems. A
dynamic model approximates the type of
organization or application that analysts deal with.
• It shows an ongoing, constantly changing status
of the system. It consists of −
– Inputs that enter the system
– The processor through which transformation takes
place
– The program(s) required for processing
– The output(s) that result from processing.

15. Important system concepts
• There are several other system concepts with
which systems analysts need to become
familiar:
• Decomposition
• Modularity
• Coupling
• Cohesion
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16. Important System Concepts
• Decomposition
– The process of breaking down a system into smaller
components
– Allows the systems analyst to:
• Break a system into small, manageable and understandable
subsystems
• Focus on one area(sub system) at a time, without interference
from other areas
• Concentrate on component pertinent to one group of users
without confusing users with unnecessary details
• Build different components at independent times and have the
help of different analysts
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17. Example
Figure 1-6 shows the decomposition of a portable MP3 player.
Decomposing the system into subsystems reveals the system’s
inner workings. You can decompose an MP3 player into at least
three separate physical subsystems
One subsystem, the battery, supplies the power for the entire
system to operate.
A second physical subsystem, the storage system,is made up of a
hard drive that stores thousands of MP3 recordings.
The third subsystem, the control subsystem, consists of a printed
circuit board (PCB),with various chips attached, that controls all of
the recording, playback, and
access functions.
Breaking the subsystems down into their components reveals
even more about the inner workings of the system and greatly
enhances our understanding of how the overall system works.
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19. Important System Concepts
(continued)
Modularity :is a direct result of decomposition. It
refers to dividing a system into chunks or modules
of a relatively uniform size. Modules can represent a
system simply, making it easier to understand and
easier to redesign and rebuild.
For example,
each of the separate subsystem modules for the MP3
player in Figure 1-6 shows how decomposition
makes it easier to understand the overall system.
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20. Important System Concepts
(continued)
Coupling
means that subsystems are dependent on each other.
Subsystems should be as independent as possible. If one
subsystem fails and other subsystems are highly
dependent on it, the others will either fail themselves or
have problems functioning.
For example:
In a home stereo system, the components are loosely
coupled because the subsystems, such as the speakers, the
amplifier, the receiver, and the CD player, are all
physically separate and function independently. If the
amplifier in a home stereo system fails, only the amplifier
needs to be repaired.
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21. Important System Concepts
(continued)
Cohesion is the extent to which a subsystem
performs a single function.
In the MP3 player example, supplying power is
a single function.
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22. Open and Closed systems
• Open system
• A system that interacts freely with its environment,
taking input and returning output
• Closed system
• A system that is cut off from its environment and does
not interact with it
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23. A Modern Approach to
Systems Analysis and Design
• Systems Integration
– Allows hardware and software from different
vendors to work together
– Enables procedural language systems to work with
visual programming systems
– Visual programming environment uses
client/server model
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24. Dining
Room
Storage Office
Kitchens
Contour
Boundary
Inputs:
Food
,labor,
cash,
etc.
Outputs:
Prepared
food
Trash
Etc.
Environments: customers, food distribution, banks, etc.
interrelationship
A fast food restaurant as a system: Example
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25. Who Develops Information
Systems?
• Traditionally, a company either developed its
own information systems, called in-house
applications, or purchased systems called
software packages from outside vendors.
• Today, the choice is much more complex.
Options include Internet-based application
services, outsourcing, custom solutions from
IT consultants, and enterprise-wide software
strategies.
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26. Regardless of the development method, launching
a new information system involves risks as well as
benefits
The greatest risk occurs when a company tries to
decide how the system will be constructed before
determining what the system needs to do:
• A company must begin by outlining its business needs
• Identifying possible IT solutions.
This important work is performed by systems
analysts and other IT professionals.
A firm should not consider implementation options
until it has a clear set of objectives. Later on, as
the system is developed ,a systems analyst’s role
will vary depending on the implementation option
selected.
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27. INFORMATION SYSTEM
COMPONENTS
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28. INFORMATION SYSTEM COMPONENTS
An information system has five key components
1. Hardware
Hardware consists of everything in the physical
layer of the information. For example, hardware
can include servers, work stations, networks,
telecommunications equipment, fiber optic cables,
handheld computers, scanners, digital capture
devices, and other technology based
Infrastructure.
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29. 2- Software
Software refers to the programs that control the
hardware and produce the desired information or
results. Software consists of: system software and
application software.
System software manages the hardware components,
which can include a single workstation or a global
network which many thousands of clients.
Application software consists of programs that
support day-to-day business functions and provide
users with the information they require.
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30. 3- Data:
Data is the raw material that an information
system transforms into useful information
4-Processes:
Processes describe the tasks and business
functions that users, mangers, and IT staff
members perform to achieve specific results.
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31. 5- People
People who have an interest in an information system are
called stakeholders. Stakeholders include the management
group responsible for the system, user, sometimes called
end users, are the people who interact with an information
systems, both inside and outside the company.
The success or failure of a system usually depends on
whether users are satisfied with the system’s output and
operation.
To serve users, successful information systems depend on
skilled professionals, such as systems analysts,
programmers, network administrators, and other IT staff
members.
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33. INFORMATION SYSTEM USERS AND THEIR NEEDS
Top Managers
Top managers develop long-range plans, called
strategic plans, which define the company’s
overall mission and goals. To plot a future course,
top managers ask questions such as
• How much should the company invest in
information technology or
• How much will Internet sales grow in the next
five years or
• Should the company build new factories or
contract out the production functions.
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34. Middle Managers and Knowledge Workers
Middle managers provide direction, necessary resources,
and performance feedback to supervisors and team
leaders.
middle managers need more detailed information than
top managers, but somewhat less than supervisors who
oversee day-to-day operations. For example,
a middle manager might review a weekly sales summary
for a three-state area, while a local sales team leader
would need a daily report on customer sales at a single
location.
Knowledge workers include professional staff members
such as systems analysts, programmers, accountants,
researchers, trainers, and human resource specialists.
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35. • Supervisors and Team Leaders
Supervisors, often called team leaders, oversee operational
employees and carry out day-to-day functions. They
coordinate operational tasks and people, make necessary
decisions, and ensure that the right tools materials, and
training are available. Like supervisors and team leaders
need decision support information, Knowledge management
systems, and user productivity systems to carry out their
responsibilities.
• Operational Employees
Operational Employees include users who rely on TP
systems to enter and receive data they need to perform their
jobs. Many companies find that empowerment
improves employee motivation and increases customer
satisfaction.
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