Introduction to MIS
Chapter 12
Systems Development

Copyright © 1998-2002 by Jerry Post

Introduction to MIS

1


En
inf terpr
o
i
sys rma se
tem tion
De
c
sup ision
sys port
Tran
tem
sact
proc
i
essi on
ng

Systems Development

Strategy

Tactics

Operations

Prototyping

Systems development life cycle

End user development

 

Introduction to MIS

 

2


Outline




Challenges in Building Information Systems
Systems Development Lifecycle (SDLC)
Alternatives to SDLC












 

Prototyping
Teamwork
Extreme Programming
End-User Development

Analyzing Systems
Process Analysis
Object-Oriented Design
Cases: Government Agencies
Appendix: Visual Basic

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3



Individual Development: Pseudocode
Project Evaluation (given a discount factor)
Get list of cost items from the user
(Description, value, time-incurred, probability-factor, category . . .)
Examine each item in the list:
Compute the present value of the cost:
PV = Cost / ( (1 + rate) ^ time)
Multiply by the probability factor:
EV = probability * PV
If item is in a special category,
Then add or subtract correction:
category = Land
Add 10%
category = Overhead
Subtract 5%
category = Labor
Add 15%
End If
Accumulate the total value
End of list
Return the Total value

 

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Top-down


Identify
Management









Functions and
Operations



Data
Programs



Operations

Programs
Introduction to MIS


 

Functions

Standards!
Integrate
Write code
Build DB
Find a problem

Operations

Databases Databases Databases

Programs
Programs



Operations

Databases Databases

Programs



Management

Entire Organization

Functions
Design Systems


 

and Bottom-up

Programs

Programs

Programs

Programs
Programs

5


Runaway Projects


Technical measures







$

Design problems




 

2 - 5 times over budget
2 - 5 times behind schedule
Missing technical objectives
Duplication of efforts
Incompatibilities
User/designer conflicts

Introduction to MIS

 

1998

2001

2002

6


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

 

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Systems Development Life Cycle
Feasibility &
Planning

Goals & plans
Systems
Analysis

Business requirements
Systems
Design

Proposal

Technical Design


Systems
Implementation

Problems &
Improvements

New System
Existing System

problems

revisions problems

revisions

Systems Maintenance: Incremental changes

 

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Development Controls






 

Detailed work plan
Performance targets
Practices & procedures
User input & control

Introduction to MIS

 

Blue Print/Planning

9


Customer Order Entry
Enter Salesperson Data

Design Tools
Visual Table of Contents

Enter/Change Customer Data
Look up Item Numbers
Enter Items Ordered

Check Inventory Status

Special Orders

Review and Print Forms

Customer Order Copy
Shipping List
Back Order List

 

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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

 

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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.

 

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12


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


 

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Implementation Options
old

Direct cutover

new

old

Parallel

new

Pilot

store 1
store 2
store 3
store 4

new

new
new
new
old

Phased

 

Introduction to MIS

dept or component 1
dept or component 2
dept or component 3
dept or component 4

 

new

14


System Evaluation

 

Introduction to MIS

 


15


SDLC Advantages & Disadvantages


Advantages








 



Control & targets
Formality
Financial controls
User input
Documentation
Testing
Ease of maintenance

Introduction to MIS


 

Disadvantages






Increased costs
Increased time
Hard for DSS
Requires definitions up front
Rigid

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Prototyping
MIS Designer

User

Initial Interview
Build Initial Prototype
New Version

Use Prototype
Request changes


Modify Prototype

Process repeats until:

 

Introduction to MIS

 

1)
2)
3)
4)
5)

User is satisfied
User and designer give up
Formal system is built from prototype
Need for application is removed
Process never ends

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Prototyping Evaluation


Advantages







Get a working system earlier
User has more input
Designed to be modified

Best uses







Problems






 

Single user
Reports
Input screens
Self-contained applications


Need 4GL trained MIS staff
Too many users
Too many analysts
Never finish
"Loss" of management
control

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18


Object Orientation
Object Orientation
Properties
Methods
Inheritance
Polymorphism

Business Objects and Processes

 

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19


Object Example
Object Classes
Object
Properties/
Attributes
Methods/
Functions

Customers
Name
Address
Phone
Change Address
Add New Customer
Delete Customer
Individual

Commercial
Contact
Account Representative
Assign Account Rep

Frequent
Contact
Account Representative
Year Started
Assign Account Rep


 

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SDLC v. Object Oriented
SDLC versus Object Oriented
60
50

% t ime

40

SDLC
Object Oriented

30
20
10
0
Requirements

 


Introduction to MIS

 

Analysis

Design

Implementation

21


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

 

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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.


 

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Teamwork Development
Coordination
Technology
Information
Sharing

Control

Access
Control

 

Introduction to MIS

Data
Sharing

 


Concurrency Consistency
Control
Enforcement

Change
Monitoring

Product

User

24


End-user Development


Advantages






Disadvantages/Problems






 

Faster
Cheaper
Get what you want

Lack of documentation
Individual/personal differences
Pre-packaged software limitations
Takes User time

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