SIM - Mc leod ch07

© 2007 by Prentice Hall Management Information Systems, 10/e
Raymond McLeod and George Schell
1
Management
Information Systems,
10/e

2
Chapter 7
Systems Development

3
Learning Objectives
►Recognize the systems approach as the
basic framework for solving problems of all
kinds.
►Know how to apply the systems approach to
solving systems problems.
►Understand that the systems development
life cycle (SDLC) is a methodology – a
recommended way to develop systems.

4
Learning Objectives (Cont’d)
► Be familiar with the main SDLC approaches – the
traditional waterfall cycle, prototyping, rapid
application development, phased development,
and business process redesign.
► Know the basics of modeling processes with data
flow diagrams and use cases.
► Understand how systems development projects
are managed in a top-down fashion.
► Be familiar with the basic processes of estimating
project cost.

5
The Systems Approach
► John Dewey identified three series of judgments
involved in adequately resolving a controversy
1.Recognize the controversy
2.Weigh alternative claims
3.Form a judgment
► During the late 1960s/early 1970s, interest in
systematic problem solving strengthened
► Systems approach—a series of problem-solving
steps that ensure the problem is first understood,
alternative solutions are considered, and the
selected solution works.

6
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 & then understanding it.
► Solution effort involves identifying alternative
solutions, evaluating them, selecting the one that
appears best, implementing that solution, &
following up to ensure that the problem is solved.

7
Figure 7.1 Phases & Steps of
Systems Approach

8
Figure 7.2 Each Business Area is a
System

9
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 & is usually more obivious
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.

10
Figure 7.3 Analyze System Parts in
Sequence

11
Select the Best Solution
►Analysis – a systematic evaluation of
options.
►Judgment – the mental process of a single
manager.
►Bargaining – negotiations between several
managers.

12
Systems Development Lifecycle
► Methodology is a recommended way of doing
something.
► Systems development lifecycle (SDLC) is an
application of the systems approach to the
development of an information system.
► Traditional SDLC stages are:
 Planning
 Analysis
 Design
 Implementation
 Use.

13
Figure 7.4 Circular Pattern of the
System Life Cycle

14
Prototyping
►Prototype is a version of a potential
system that provides the developers &
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.

15
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.

16
Figure 7.5 Development of
Evolutionary Prototype

17
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.

18
Figure 7.6 Development of
Requirements Prototype

19
Attraction of Prototyping
► Communications between the developer & 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 & the user spend less time & effort
developing the system.
► Implementation is much easier because the user
knows what to expect.

20
Potential Pitfalls of Prototyping
► The haste to deliver the prototype may produce
shortcuts in problem definition, alternative
evaluation, & 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.

21
Rapid Application Development
► 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 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, &
tools.
► Best suited for large systems.

22
Figure 7.7 Rapid Application
Development

23
Phased Development
► Phased development is an approach for
developing information systems that consists of six
stages:
 Preliminary investigation
 Analysis
 Design
 Preliminary construction
 System test
 Installation.
► Best suited for systems of all sizes.

24
Figure 7.8 Stages of Phases
Development

25
Module Phases
►System is subdivided into major modules
such as:
 Report writer;
 Database;
 Web interface.
►Number of modules varies with the system
from 1 to a dozen or so.
►Stages are performed separately for each
module.

26
Figure 7.9 Module Phase of Systems
Development

27
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
& 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.

28
Figure 7.10 Top-Down Initiation of
BPR Projects

29
Strategic Initiation of BPR
► Reverse engineering is the process of analyzing
an existing system to:
 identify its elements & 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.

30
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.

31
Figure 7.11 BPR Component
Selection

32
Methodologies in Perspective
►Traditional SDLC is an application of the
systems approach to the problem of system
development; contains all elements.
►Prototyping is an abbrev. form focusing on
the definition & satisfaction of user needs.
►RAD is an alternative approach to the
design & implementation phases of SDLC.
►Phased development uses traditional
SDLC & applies it in a modular fashion.

33
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.

34
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.

35
Figure 7.12 DFD of a Sales
Commission System

36
Leveled Data Flow Diagrams
► Leveled DFDs is used to describe the hierarchy of
diagrams, ranging from context to lowest-level n diagram.
► Figure 0 diagram identifies the major processes of a
system.
 Use additional DFDs to achieve documentation at both a more
summarized & a more detailed level.
► Context diagram is a diagram that documents the
system at a more summarized level.
 Positions the system in a 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.

37
Figure 7.13 Context Diagram of a
Sales Commission System

38
Figure 7.14 Figure 4 Diagram of a
Sales Commission System

39
Use Cases
► Use case is a narrative description in an outline
form of the dialog that occurs between a primary
& secondary system.
► Continuous narrative format with each action
numbered sequentially.
► Ping-pong format consists of two narratives &
the numbering indicates how the tasks alternate
between the primary & secondary systems.
► Alternative events are actions that are not
normally expected to occur; alphabetic letters are
appended to step numbers.

40
Figure 7.15 A Use Case

41
Figure 7.16 Use Case Guidelines

42
Project Management
►Steering committee is a committee with
the purpose of providing ongoing guidance,
direction, & 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.

43
Figure 7.17 Managers of a System
Life Cycle Arranged in a Hierarchy

44
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.

45
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 & 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.

46
Figure 7.18 A Gantt Chart

47
Figure 7.19 A Network Diagram

48
Project Cost-Estimating
► Cost-estimating inputs
 Work breakdown structure (WBS)
 Resource requirements, resource rates
 Activity duration estimates
 Historical information
► Cost-estimating tools & techniques
 Bottom-up estimating
 Computerized estimating
 Mathematical models
► Cost-estimating outputs
 Supporting details
 Cost-management plan

49
Table 7.1 Components of Cost-
Estimating Process

50
Table 7.2 Example of Project Cost

SIM - Mc leod ch07

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à SIM - Mc leod ch07

Similaire à SIM - Mc leod ch07 (20)

Dernier

Dernier (20)

SIM - Mc leod ch07