2. OVERVIEW
System approach
The Software Development Life Cycle
Traditional SDLC
Prototyping
Rapid Application Development (RAD)
Phased Development
Business Process Redesign (BPR)
Strategic Initiation of BPR Projects
Reverse Engineering
Reengineering
System Development Tools
Process Modeling, DFD, Use Cases 2
3. THE SYSTEMS APPROACH
John Dewey identified three series of
judgments involved in resolving a
controversy:
• Recognize the controversy.
• Weigh alternative claims.
• Form a judgment.
Systems approach
a series of problem-solving steps that ensure
the problem is first understood, alternative
solutions are considered, and the selected
solution works.
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4. SERIES OF STEPS
Preparation effort
prepares the problem solver by providing a
systems orientation.
Business areas, level of management, resource flows
Definition effort
consists of identifying the problem to be solved and
then understanding it.
Solution effort
involves identifying alternative solutions, evaluating
them, selecting the one that appears best,
implementing that solution, and following up to
ensure that the problem is solved.
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7. DEFINITION EFFORT TERMINOLOGY
Problem trigger
is a signal that things are going better or worse than
planned.
Symptom
is a condition that is produced by the problem and is
usually more obvious than the root cause of the
problem.
Problem
is a condition or event that is harmful or potentially or
beneficial or potentially beneficial to the firm.
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8. EACH PART OF THE SYSTEM IS
ANALYZED IN SEQUENCE
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9. SELECT THE BEST SOLUTION
Analysis
a systematic evaluation of options.
Judgment
the mental process of a single manager.
Bargaining
negotiations between several managers.
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10. SYSTEMS DEVELOPMENT LIFE CYCLE
SDLC
is an application of the systems approach to
the development of an information system.
Traditional SDLC stages are:
Planning
Analysis
Design
Implementation
Use
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12. PROTOTYPING
Prototype
is a version of a potential system that provides
the developers and future users with an idea of
how the system in its completed form will
function.
Prototyping is the process of producing a
prototype.
Best suited for small systems–reflecting the
prototyping influence.
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13. EVOLUTIONARY PROTOTYPE
Evolutionary prototype
is continually refined until it contains all of the
functionality that users require of the new
system.
The steps involved are:
Identify user needs.
Develop prototype.
Integrated application developer
Prototyping toolkit
Determine if the prototype is acceptable.
Use the prototype. 13
15. REQUIREMENTS PROTOTYPE
Requirements prototype
is developed as a way to define the functional
requirements of the new system when users
are unable to articulate exactly what they want.
Begin with the Evolutionary Prototype steps, then the
next steps are:
Code the new system;
Test the new system;
Determine if the new system is acceptable;
Put the new system into production.
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17. ATTRACTION OF PROTOTYPING
Communications between the developer
and user are improved.
The developer can do a better job of
determining the users’ needs.
The user plays a more active role in system
development.
The developers and the user spend less
time and effort developing the system.
Implementation is much easier because the
user knows what to expect.
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18. POTENTIAL PITFALLS OF PROTOTYPING
The haste to deliver the prototype may
produce shortcuts in problem definition,
alternative evaluation, and documentation.
The shortcut produces a “quick & dirty”
effort.
The user may get overly excited about the
prototype, leading to unrealistic
expectations regarding the production
system.
Evolutionary prototypes may not be very
efficient.
The computer-human interface provided by
certain prototyping tools may not reflect
good design techniques. 18
19. RAPID APPLICATION DEVELOPMENT
RAD
is a term coined by James Martin. It refers to a
development life cycle intended to produce
systems quickly without sacrificing quality.
Information engineering (IE)
is the name that Martin gives to his overall
approach to system development, which treats
it as a firm-wide activity.
Enterprise
is used to describe the entire firm.
Essential to RAD is management, people,
methodologies, and tools.
Best suited for large systems.
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20. PHASED DEVELOPMENT
Phased development
is an approach for developing information
systems that consists of six stages:
Preliminary investigation
Analysis
Design
Preliminary construction
Final construction
System test
Installation.
Best suited for systems of all sizes. 20
22. MODULE PHASES
System is subdivided into major modules
such as:
Report writer;
Database;
Web interface.
Number of modules varies with the system
from one to a dozen or so.
Stages are performed separately for each
module.
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23. ANALYSIS, DESIGN, AND PRELIMINARY CONSTRUCTION ARE
PERFORMED ON EACH SYSTEM MODULE
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24. BUSINESS PROCESS REDESIGN
Reengineering or Business process redesign
(BPR) is the process of reworking the systems.
Systems include both those that process the firm’s
data and those that perform basic functions such as
drilling for oil.
BPR affects the firm’s IT operations in two
ways:
Aids in the redesign of old information systems
(legacy systems);
Applies to the redesign of information systems to
support major operations.
Usually initiated at strategic management level
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26. STRATEGIC INITIATION OF BPR
Reverse engineering
is the process of analyzing an existing system
to:
Identify its elements and their interrelationships;
Create documentation at a higher level of
abstraction than currently exists.
Functionality is the job that it performs.
Reengineering
is the complete redesign of a system with the
objective of changing its functionality.
Forward engineering
is given to the process of following the SDLC
in the normal manner while engaging in BPR.
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27. BPR COMPONENTS
BPR components can be applied separately or in
combination.
Functional quality
is a measure of what the system does.
Technical quality
is a measure of how well it does it.
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29. METHODOLOGIES IN PERSPECTIVE
Traditional SDLC
is an application of the systems approach to the
problem of system development; contains all
elements.
Prototyping
is an abbreviated form focusing on the definition
and satisfaction of user needs.
RAD
is an alternative approach to the design and
implementation phases of SDLC.
Phased development
uses traditional SDLC and applies it in a modular
fashion.
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30. SYSTEM DEVELOPMENT TOOLS
Process modeling was first done with
flowcharts.
ISO standards
Use of 20+ symbols
Data flow diagrams (DFD)
is a graphic representation of a system that
uses four symbol shapes to illustrate how data
flows through interconnected processes.
DFDs are excellent for modeling processes
at a summary level. 30
31. DATA FLOW DIAGRAM SYMBOLS
Terminator
describes an environmental element, such as a person,
organization, or another system.
Environmental elements exist outside the boundary of the
system.
Process
is something than transforms input into output.
Data flow
consists of a group of logically related data elements that
travel from one point or process to another; can diverge and
converge.
Data storage
is a repository of data.
Connector
contains the number of the process that provides the data
flow. 31
33. LEVELED DATA FLOW DIAGRAMS
Leveled DFDs is used to describe the hierarchy of
diagrams, ranging from context to lowest-level n
diagram.
Diagram identifies the major processes of a system.
Use additional DFDs to achieve documentation at both a
more summarized and a more detailed level.
Context diagram is a diagram that documents the
system at a more summarized level.
Positions the system in an environmental context.
Figure n diagram is a diagram that provides more
detail.
n represents the # of processes on the next higher level.
Documents a single process of a DFD in greater detail
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35. A FIGURE 4 DIAGRAM OF A SALES
COMMISSION SYSTEM
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36. USE CASES
Use case
is a narrative description in an outline form of
the dialog that occurs between a primary and
secondary system.
Continuous narrative format
with each action numbered sequentially.
Ping-pong format
consists of two narratives and the numbering
indicates how the tasks alternate between the
primary and secondary systems.
Alternative events are actions that are not
normally expected to occur; alphabetic
letters are appended to step numbers. 36
39. PROJECT MANAGEMENT
Steering committee
is a committee with the purpose of
providing ongoing guidance, direction,
and control of all systems projects.
MIS steering committee
purpose is directing the use of the firm’s
computing resources.
It establishes policies.
It provides fiscal control.
It resolves conflict. 39
40. MANAGERS OF A SYSTEM LIFE CYCLE
ARRANGED IN A HIERARCHY
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41. PROJECT LEADERSHIP
Project team
includes all of the persons who participate in the
development of an information system.
Team leader (project leader)
provides direction throughout the life of the
project.
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42. PROJECT MANAGEMENT MECHANISM
Basis for project management is the project
plan.
Gantt chart
is a horizontal bar chart that includes a bar for
each task to be performed; bars arranged in time
sequence.
Network diagram (CPM diagram, PERT
chart)
is a drawing that identifies activities and links them
with arrows to show the sequence in which they
are to be performed.
Narrative reports are in the form of weekly
written reports by project leader, communicates
project information to MIS steering committee.
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