IT_Chapter_12B

Systems Development Life Cycle

• Organized way to build information systems

• Consists of five phases

– Entire usable life of the system

• Phase 1: needs analysis

– Users identify a need

– Solves three main problems

• Define the problem

• Present possible solutions

• Determine the best solution

– Technology analysts talk with users

– Define the problem using a description tool

– A solution is presented to a manager

• Phase 2: Systems design

– Solution is defined

• Data storage

• User interface

• Reports

– Several design tools

• Top down design

• Bottom up design

– CASE tools used to build prototypes

• Computer aided software engineering

• Phase 3: Development

– Solution to the problem is built

– Programmers play a key role

– Solutions may be purchased

– Solutions may be built locally

– Technical writers create instructions

– Solution is repeatedly tested

• Phase 4: Implementation

– Installation of hardware and software

– Users must convert to the solution

• Direct conversion

• Parallel conversion

• Phased conversion

• Pilot conversion

– Trainers and support personnel are critical

• Phase 5: Maintenance

– IT professionals continue to monitor

– Bugs are fixed

– New features are added

– Users often suggest bugs or features

Evolving System Design Methods

• Problems with SDLC

– SDLC is an old process

– Very slow process

– Companies need to respond quickly

• Rapid Application Design (RAD)

– Develops IS systems quickly

– Several products exist

– Slightly different development phases

• RAD Phase 1: Requirements planning

– Requirements for project are defined

– Joint requirements planning (JRP)

• Involves programmers and managers

– Managers from affected departments provide guidance

• RAD Phase 2: User design

– Joint application design (JAD)

• System analysts and users

– User provides the details

– System analyst solve the technical details

• RAD Phase 3: Rapid construction

– IS professionals develop the project

– A variety of tools can be used

– Users approve each portion

• RAD Phase 4: Transition

– System is tested on sample data

– Users are trained on the sample

– New system runs parallel to existing

– Phase complete when bugs are gone

– Old system removed

• RAD Phase 5: Maintenance

– Traditionally not part of RAD

– All systems need periodic maintenance

• Object Oriented Systems Analysis

– OOSA

– Project elements are defined using objects

• Objects are self contained programming constructs

• Objects have data and functionality

– Objects are linked together

– Java and C++ are typical tools