1. Information Systems Development (ISD)
• Overview
1) From 50s until the 60s it was common for programmers to program any way they liked.
The result was that no one, often not even code originators, could read code and know what it was suppose to be.
Programmers tried to make maximum use of limited computer storage. This necessitated very compact code which let to a lack of clarity.

2. Information Systems Development (ISD)
• Overview
2) From 60s until end of 70s the industry strove to introduce “structured” programming. This improved code consistency between programmers and helped with understandability and maintenance.
Structured code - What is it?
We agree to use just 3 programming structures:
a)Sequence
b) Decision
c) Iteration

3. Information Systems Development (ISD)
• Structured Code
Divide the program into modules which perform just one task.
Use the 3 structures to program the modules.
Each module not longer than 25 lines.
Avoid CO-TO statements because they lead to spaghetti code.

4. Information Systems Development (ISD)
• Structured Design
1) Uses the process of decomposition to generate a modular structure
2) A module receives data, processes data, outputs the results.
3) Data moves from one module to the next until a particular process has been completed
4) Program decomposition is a very difficult task

5. Information Systems Development (ISD)
• Standard Development Life Cycle (SDLC)
1) System Analysis user request
feasibility
project plan
2) Logical Design define user info needs
use 3 structures for logic
design
3) Physical Design system decomposition
database design

6. Cont’d
4) Programming code programs
test programs
document
5) Implementation test system
train users/operators
data conversion
6) Operation run the system
maintain system

7. Information Systems Development (ISD)
• SDLC Drawbacks
1) System design is a non-linear process
2) Problems created in System Analysis are often not detected until implementation
3) Users have great difficulty describing information needs
4) ISD risks are usually at the expense of the user
5) Different groups of people are involved during design process

8. Cont’d
6) The SDLC suggests that we can loop back but this is difficult if not impossible.
7) Basically, the SDLC forces a linear process.

9. Information Systems Development (ISD)
• Prototyping Method
1) Needed:
High level programming language
Flexible data base
User interface
2) What is prototyping?
Why use it? Advantages? Disadvantages? What types of prototyping?
Test plan needed

10. Information Systems Development (ISD)
1) Discuss information needs with users
2) Build a prototype in short time
3) Present to user for testing
4) Get user suggestions for improvement
5) Reprogram prototype and go back to user for more round of test.

11. Information Systems Development (ISD)
We need a well-thought out test program.
How do we decide when to stop?
How do we decide what features the prototype should have?
What happens to the prototype when our testing is completed?
(Relate prototyping engineering case)

12. Information Systems Development (ISD)
What is a Pilot System?
Why use it?
Advantages
Disadvantages
Case study