INFSY540
Chapter 12
Systems Development
Copyright © 1998 by Jerry Post
1
Systems Analysis and Design

Systems Analysis


Systems Design


Put system together (creative, in a way)
Tear systems apart into their component parts to:



Tear system apart (destructive, in a way)
To really understand the simpler components. (Because it is
too hard to understand the system as a whole.)
To put them back together better than they were before.
Systems Development = Systems Analysis + Design
3
Systems Analysis and Design


Requires a method or there will be madness.
Need to meet organization requirements without
exceeding organizational constraints.


Identifying and articulating requirements is not easy. But it is
absolutely essential.
Resources must be considered, otherwise you might not be
able to get there from here.
4
Top-down

Identify Management




and Bottom-up

Functions and
Operations

Entire Organization
Design Systems




Functions
Data
Programs
Operations
Programs
Operations
Databases Databases Databases
Programs
Programs
Functions
Operations
Databases Databases
Programs

Management
Standards!
Integrate
Write code
Build DB
Find a problem
Programs
Programs
Programs
Programs
Programs
6
Runaway Projects

Technical measures




$
2 - 5 times over budget
2 - 5 times behind schedule
Missing technical objectives
Design problems



Duplication of efforts
Incompatibilities
User/designer conflicts
1994
1996
1998
7
Success & Failure

Reasons for Success





User Involvement
Executive management
support
Clear requirements
Proper planning
Realistic expectations

Reasons for Failure





Lack of user input
Incomplete requirements
Changing requirements and
specifications
Lack of executive support
Lack of technical skills
Cafasso 1994
8
Projects

What are projects?


Out of the ordinary work.
A (temporary) sequence of activities having a common
purpose that is supposed to be completed by a specified time,
within budget and according to specifications.
10
How do you evaluate projects?

Constraints of projects






Technical feasibility
Operational feasibility
Schedule feasibility
Economic feasibility
Legal feasibility
C
o
n
s
t
r
a Met
i
n
t Not Met
s
Criteria of projects





Technical Objectives
Operational Objectives
Schedule Objectives
Economic Objectives
Legal Objectives
Criteria
Do Well
Don’t Do Well
Great
Ok
Bad
Bad
12
Process versus Methodology
A system development process is a set of activities,
methods, best practices, deliverables, and automated
tools that stakeholders use to develop and maintain
information systems and software.
A system development methodology is a very formal
and precise system development process that defines
a set of activities, methods, best practices,
deliverables, and automated tools that system
developers and project managers are to use to
develop and maintain information systems and
software.
13
Principles of System Development

Get the owners and users involved.

Use a problem-solving approach.

Establish phases and activities.

Establish standards.

Justify systems as capital investments.

Don’t be afraid to cancel or revise scope.

Divide and conquer.

Design systems for growth and change.
15
Life Cycles

What are they?


Give an example of a generic life cycle.
Why are they important to anyone creating
systems?

When do people try to replace existing systems?

When do creatures replace themselves?
16
Life Cycles

What are they?


Give an example of a generic life cycle.
Why are they important to anyone creating
systems?

When do people try to replace existing systems?


When they break, when they are dying?
When do creatures replace themselves?

When the creature is in its early maturity
17
Examples of Life Cycles
Conception
Analysis
Analyze
Birth
Design
Design
Youth
Develop
Construct
Adolescence
Implement
Implement
Adult
Use
Elderly
Maintain
Death
Retire
Burial
Destruction
19
Systems Development Life Cycle
Feasibility &
Planning
Goals & plans
Systems
Analysis
Proposal
Problems &
Improvements
Business requirements
Systems
Design
Technical Design
Systems
Implementation
New System
Existing System
problems
revisions problems
revisions
Systems Maintenance: Incremental changes
20
Phases of a Representative Methodology
21
Project Identification and Initiation

Problems are undesirable situations that prevent the
organization from fully achieving its purpose, goals,
and/or objectives.

Opportunities are chances to improve the
organization even in the absence of specific problems.

Directives are new requirements that are imposed by
management, government, or some external influence.
23
The PIECES Problem-Solving Framework
P
performance
I
information
E
economics, costs, profits
C
control or security
E
efficiency of people and processes
S
service
25
Alternative Routes through a Methodology

Model-Driven Development (MDD)

Rapid Application Development (RAD)

Commercial Off-the-Shelf Software (COTS)

Maintenance and Reengineering
or hybrids of the above
26
Model-Driven Development (MDD) Route
27
Rapid Application Development (RAD) Route
28
Commercial Off-the-Shelf (COTS) Software Route
29
Maintenance and Reengineering Route
30
Process and Project Managers

A process manager is an automated tool that helps to document
and manage a methodology and routes, its deliverables, and
quality management standards.

A project manager is an automated tool to help plan system
development activities (preferably using the approved
methodology), estimate and assign resources (including people
and costs), schedule activities and resources, monitor progress
against schedule and budget, control and modify schedule and
resources, and report project progress.
31
Information Systems Architecture
Information systems architecture provides a unifying
framework into which various people with different
perspectives can organize and view the fundamental
building blocks of information systems.
32
Perspectives or Stakeholders






System owners pay for the system to be built and maintained.
System users use the system to perform or support the work to
be completed.
System designers design the system to meet the users’
requirements.
System builders construct, test, and deliver the system into
operation.
Systems analysts facilitate the development of information
systems and computer applications by bridging the
communications gap that exists between nontechnical system
owners and users and technical system designers and builders.
IT vendors and consultants sell hardware, software, and
services to businesses for incorporation into their information
systems.
33
Focuses for Information Systems



Data—the raw material used to create useful
information.
Processes—the activities (including management)
that carry out the mission of the business.
Interfaces—how the system interfaces with its users
and other information systems.
34
Information System Building Blocks
35
Information System Building Blocks
40
Comparison of Diagrams

Data Flow Diagram





Show process and flow of
data.
Process
No
Increasingly detailed levels
of process.

Entity Relationship Diagram




Describe
Data structures.
Yes
By entities or object
inheritance.
Structure Chart or VTOC




Show modules and usage
flow.
Module structure
No
By program structure or
usage steps.
Purpose, Classification, Object Orientation, Decomposition
41
SDLC Effort
Stage
Procedure
Approx. Pct. Of Effort
Analysis
Feasibility
Requirements
Conceptual Design
5
15
5
Design
Physical Design
Programming
Procedure Develop.
20
25
10
Implementation
Conversion
15
Maintenance & Review
Review
Maintenance
5
not included
G. Davis and M. Olson, Management Information Systems 1985.
42
Systems Implementation







Final testing
Involve users
Education and training
Flexibility
Recognize how the system
will affect the business
Encourage users to change
Implementation plans
Education and training
Changing
Business operations
43
Implementation Options
old
Direct cutover
new
old
Parallel
new
Pilot
store 1
store 2
store 3
store 4
new
new
new
new
old
Phased
new
dept or component 1
dept or component 2
dept or component 3
dept or component 4
44
Factors to Consider During Systems Review







Mission
Goals
Hardware/ software
Database
Telecommunications
IS personnel
Control







Training
Costs
Complexity
Reliability
Efficiency
Response time
Documentation
45
System Evaluation
Feasibility
Comparison
Cost & Budget
Time Estimates
Revenue Effects
Maintenance Costs
Project Goals
User Satisfaction
System Performance
System Reliability
System Availability
System Security
Compare actual costs to budget estimates.
Was project completed on time?
Does system produce additional revenue?
How much money and time are spent on changes?
Does system meet the initial goals of the project?
How do users (and management) evaluate the system?
Are the results accurate and on time?
Is the system available on a continuous availability?
Does the system provide access to authorized users?
46
Objects & Events
Events
Sale
Methods
Record Sale
Update Inventory
Notify Customer
Service
Inventory
Order/JIT
Notify Suppliers
Schedule Payment
Objects
Transaction Log
Accounts & Ledgers
Inventory
Customers
Employees (commissions)
Accounts & Ledgers
Suppliers
Shipping/Receiving
Installation
& Maintenance
47
Developing Systems with Teams
Developing systems is generally a team
effort among MIS developers and
business users. Groupware, CASE, and
development tools are often used to
facilitate communication and
coordination.
48
Teamwork Development
Coordination
Technology
Information
Sharing
Control
Access
Control
Data
Sharing
Concurrency Consistency
Control
Enforcement
Change
Monitoring
Product
User
49
End-user Development

Advantages




Faster
Cheaper
Get what you want
Disadvantages/Problems




Lack of documentation
Individual/personal differences
Pre-packaged software limitations
Takes User time
50
End-user Development
When to Call for Help

Many people use the system







PC versus central computer
Need documentation
Individual user differences
Need to train users
Commercial software limits
User time is expensive
Mission critical application




Need to integrate




Use corporate data
Tie to existing software
Connect to network
Database Integrity


Avoid duplicate data
Changes to corporate data
Additional testing
Many modifications
Need security & control
51
Who Should Develop Systems?

MIS




Size: Many users
Complexity: Different
departments
Long development time



Critical Information



Major changes to central
data base
Formal testing
Expensive hardware



SDLC large project controls
Cost of user time
Formal feasibility
Compatibility
End User




One-time code
Can purchase pre-packaged
solutions
Highly trained users
How Can MIS Help?





Easy access to
data/database
Advice and help
Testing & quality control
Training & tutorials
Information Center
Specialized knowledge
52
Math functions
Abs
Absolute value
Atn
Arc Tangent
Cos
Cosine
Exp
Exponential
Fix
Returns integer portion
Int
Converts to integer
Log
Logarithm
Rnd
Random number
Sgn
Signum (-1, 0, 1)
Sin
Sine
Sqr
Square root
Tan
Tangent
String functions
StrComp
LCase, UCase
Len
Format
InStr, Left, LTrim
Mid, Right, RTrim, Trim
Appendix: Visual Basic

Programming Logic

Computations






Variables
Internal functions
Conditions
Loops
Input
Output
Compare two strings
Convert to lowercase or uppercase
Find length of a string
Format a string
Manipulate strings.
55
VB: Conditions
If (condition) Then
statements if true
Else
statements if false
End If
Select Case Customer
Case Customer = ‘Corporate’
If (Sales > 1000) Then
Bonus = 100
Discount = 0.05
Case Customer = ‘Government’
Discount = 0.10
Else
Bonus = 0
End If
Case Else
Discount = 0.01
End Select
56
VB: Loops
total = 0
For month = 1 To 12
total = total + SalesForMonth(month)
Next month
month = 0
sales = 0
Do Until (sales > 100000)
sales = sales + SalesForMonth(month)
month = month + 1
Loop
57
VB: Input and Output
Could use: InputBox, MsgBox, and Printer object.
Generally just use data in the application.
In this example, the form collects the data and displays the result.
58
Sub Macro1()
' Keyboard Shortcut: Ctrl+Shift+U
For Each c In Selection
c.Value = PCase(c.Value)
Next c
End Sub
VBA: Excel Example
Function PCase(txt)
' Convert a text value to proper case
Dim i As Integer
txt = LCase(txt)
Mid(txt, 1, 1) = UCase(Mid(txt, 1, 1))
i=2
Do While (i > 0) And (i < Len(txt))
i = InStr(i, txt, " ")
If (i > 0) And (i < Len(txt)) Then
Mid(txt, i + 1, 1) = UCase(Mid(txt, i + 1, 1))
i=i+1
End If
Loop
PCase = txt
End Function
ALTA
SNOWBASIN
BRIGHTON
PARK CITY
DEER PARK
SOLITUDE
143
154
113
115
120
137
Alta
Snowbasin
Brighton
Park City
Deer Park
Solitude
143
154
113
115
120
137
59
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