3. Chapter Outline
Developing an IT architecture
Overview the Traditional SDLC
Alternative methods and tools for systems development
Component- based development and web services
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4. Learning Objectives
Describe the hierarchy and steps of IT
architecture.
Describe the SDLC and its advantages and
limitations.
Describe the major alternative methods and
tools for building information systems.
Describe the use of component- based
development and web services.
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5. TG6.1 Developing an IT Architecture
Koontz (2000) suggested a six-step process for
developing an IT architecture
Step1: Business goals and vision. The system analyst
reviews the relevant business goals and vision.
Step 2 : Information architecture. A company analyst
defines the information necessary to fulfil the
objectives of step 1.
Step 3: Data architecture. What data you have and
what you want to get form customers, including Web-generated
data.
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6. Step 4: Application architecture. Define the components
or modules of the applications that will interface with the
required data. Build the conceptual framework of an
application, but not the infrastructure that will support it.
Step 5: Technical architecture. Formally examine the
specific hardware and software required to support the
analysis in previous step.
Step 6: Organizational architecture. An organizational
architecture deals with the human resources and
procedure required by steps 1 through 5
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7. TG6.2 Overview of SDLC
Systems development life cycle (SDLC) is a
structured framework used for large IT
projects, that consists of sequential
processes by which information systems are
developed.
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8. An eight- stage system development life cycle
(SDLC)
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9. Waterfall approach. SDLC approach in which
tasks in one stage were completed before the
work proceeded to next stage
Systems analysts. IS professionals who
specialize in analyzing and designing
information systems.
Programmers. IS professionals who modify
existing computer programs or write new
computer programs to satisfy user
requirements.
Technical specialist. Experts on a certain type
of technology, such as databases or
telecommunications
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10. Systems stakeholders
All people who are affected by changes in
information systems
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11. S ystems investigation
Systems investigation begins with the business
problem (or business opportunity).
The next task in the systems investigation stage
is the feasibility study that gauges the probability
of success of a proposed project and provides
rough assessment of the project's feasibility.
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12. Feasibility study
Technical feasibility: Assessment of whether
hardware, software and communications
components can be developed and /or
acquired to solve a business problem.
Economic feasibility: Assessment of whether a
project is an acceptable financial risk and if the
organization can afford the expense and time
needed to complete it.
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13. Economic feasibility
Return on investment. The ratio of the net
income attributable to a project divided by the
average assets invested in the project.
Net present value. The net amount by which
project benefits exceed project costs of capital
and the time value of money.
Breakeven analysis. Method that determines the
point at which the cumulative cash flow from a
project equals the investment made in the
project.
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14. F easibility study cont…
Organizational feasibility . organization’s
ability to access the proposed project.
Behavioural feasibility. Assessment of the
human issues involved in a proposed
project, including resistance to change
and skills and training needs.
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15. Systems analysis
The examination of the business problem that
the organization plans to solve with an
information system. This stage defines the
business problem, identifies its causes,
specifies the solution and identifies the
information requirements that the solution
must satisfy
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16. Systems Analysis cont…
Organization have three basic solutions to
any business problem relating to an
information system:
Do nothing and continue to use the existing
system unchanged,
Modify or enhance the existing system,
Develop a new system.
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17. There are problems associated with eliciting
information requirement, regardless of the method
used by the analyst.
The business problem may be poorly defined
The users may not know exactly what the problem is,
what they want or what they need.
Users may disagree with each other about business
procedures or even about the business problem.
The problem may not be information related, but may
require other solutions, such as a change in
management or additional training.
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18. The system analysis stage produces the
following information:
Strengths and weaknesses of the existing system
Functions that the new system must have to
solve the business problem.
User information requirements for the new
system.
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19. Systems design
System analysis describes what a system must do to solve
the business problem and systems design describes how
the system will accomplish this task . The deliverable of the
systems design phase is the technical design that specifies
the following :
System outputs, inputs and user interfaces
Hardware, software, databases, telecommunications,
personnel and procedures
How these components are integrated
This output represents the set of system specification
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20. System design encompasses two major
aspects of the new system:
Logical system design: states what the
system will do, using abstract specifications.
Physical system design: states how the
system will perform its functions, with actual
physical specification.
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21. Programming
The translation of a system’s design specification
into computer code.
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22. Testing
Testing check to see if the computer code will
produce the expected and desired results under
certain conditions
Testing is designed to delete errors (bugs) in the
computer code. These errors are of two types .
Syntax errors ( e.g., misspelled word or a
misplaced comma) and logic errors that permit
the program to run but result in incorrect output
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23. Implementation
Implementation or deployment is the process of converting
from the old system to the new system. Organizations use
four major conversion strategies ; parallel , direct , pilot and
phased.
Parallel conversion. Implementation process in which the
old system and the new system operate simultaneously for a
period of time.
Direct conversion. Implementation process in which the old
system is cut off and the new system turned on at a certain
point in time.
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24. Implementation cont…
Pilot conversion. Implementation process that
introduces the new system in one part of the
organization on a trial basis, when new system is
working property, it is introduced in other parts of the
organization.
Phased conversion. Implementation process that
introduces components of the new system in stages,
until the entire new system is operational.
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25. Operation and maintenance
Systems need several types of maintenance.
Debugging: A process that continues throughout the
life of the system.
Updating: updating the system to accommodate
changes in business conditions.
Maintenance: that adds new functionally to the
system –adding new features to the existing system
without disturbing its operation.
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26. TG6.3 Alternative methods and tools for
systems development
Prototyping
Joint application design (JAD)
Rapid application development (RAD)
Object- oriented development
Other methods
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27. Alternative methods cont…
Prototyping. Approach that defines an initial
list of user requirements, builds a prototype
system and then improves the system in
several iterations based on users’ feedback.
Joint application design (JAD). A group –
based tool for collecting user requirements
and creating system designs.
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28. Alternative methods cont…
Rapid application development . A
development method that uses special tools
and an iterative approach to rapidly produce a
high-quality system.
Computer-aided software engineering (CASE).
Development approach that uses specialized
tools to automate many of the tasks in the
SDLC; upper CASE tools in SDLC automate
the early stages of the SDLC, and lower case
tools automate the later stages.
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29. Alternative methods cont…
Integrated Computer Assisted software
Engineering (ICASE) Tools . CASE tools that
provide links between upper CASE and lower
CASE tools.
Object- oriented development. Begins with
aspects of the real world that must be
modelled to perform a task.
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30. TG6.4 Component-based development
(CBD) and web service
CBD: A method that uses pre-programmed
components to develop application.
Web service in system development: Self-contained,
self-describing business and
consumer modular applications, delivered over
the Internet, that users can select and combine
through almost any device.
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31. Web services advantages and
limitations
Advantage Disadvantage
Greater interoperability and lower costs due to
universal, open, text-based standards
Standards still being defined
Enable software running on different platforms to
communicate with each other
Require programming skill to implement
Promote modular programming and reuse of
existing software.
Security: applications may be able to
bypass security barriers
Operate on existing Infrastructure, so are easy
and inexpensive to implement.
Can be implemented incrementally
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