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Project Life Cycles
System development life cycle
• Waterfall model
• Spiral model
• Whirlpool model
• Rugby model
• OMG model
Waterfall model
projectdefinition
system study
design
programming
Installation
Post Imple-mentation
Project proposal report
Functional specifications
Feasibility report
design specifications
program specificationscode
system performance tests
audit , feed-back- intermediate reports
- go/nogo intervals
Boehm’s Spiral Model
prototype 1prototype 2
operationalprototype
RiskAnalysis
RiskAnalysis
RiskAnalysis
determine objectives,alternativesconstraints
evaluate alternativesidentify , resolve risks
simulationmodels Benchmarksrequirements plan
life cycle plan concept ofoperation
Software design
Designvalidation and verification
integrationtests and plan
detailed design
coding
integration tests
implementation
progressthroughsteps
Plannext phases
Prototype based
Whirlpool model
projectdefinition
system study
design
programming
Installation
Post Imple-mentation
Project proposal report
Functional specifications
Feasibility report
design specifications
program specifications
code
system performance tests
audit , feed-back
After each phase a quick review of the previous phases is made
OO-life cycle
With the increasing complexity of the systems,
the structured techniques suffer from two
illusions:
The analyst knows everything and understands the problem completely before implementation starts
The users read the system analysis report and approve it
OMG-model (Object Management Group )
Facts: System requirements are not fully known at the startknowledge of the system grows during development
better develop a system incrementallystart with some core functions
object modelling
analysis
design
construction
fullsystemdefinition
coordination and reuse
OMG Project Management
Iterative styledevelop a series of solutions to a problem ,
each of them closer to satisfying the requirements
( also called : evolutionary development )
Incremental styleBuilds system functionality a little at a time.
The results are not entire solutions.
Matthew Pittman proposes iterative analysis and design combined with incremental development
Problem is managing the reuse (by design , not by accident)
How can such a project be estimated , tracked , controlled
The Waterfall Model
Waterfall model
projectdefinition
system study
design
programming
Installation
Post Imple-mentation
Project proposal report
Functional specifications
Feasibility report
design specifications
program specificationscode
system performance tests
audit , feed-back- intermediate reports
- go/nogo intervals
Project definition
What do we want to accomplish ?
- solve a new problem
- incorporate new requirements
- improve existing system
Is a new system the best solution ?
Who will be involved ?
Organizational problem
System study : functional specs
Objective: What is the problem ?
Responsibility: The user
Execution: Top-down technique
1. Activities: just a few sentences
2. Logical operations ( processes): for each activity
3. Details and definitions: rules, actions, controls , forms
4. Detail information:
object, units, begin and end, classes, names
System study : functional specs 2
The problem definition report includes: For the input:
form point of time and frequency origin responsibility
For the output: type and layout point of time and frequency destination usage
Furthermore: reasons for realization financial advantages constraints and borders of the system
System study : The feasibility study
Responsibility from this phase on in the ICT-department study of the existing system borders of the new system links with other systems study of different solutions division in subsystems applicability of packages estimation of personnel requirements cost-benefit analysis
The report allows the steering committee to: - fix timings - final decision
Design : general
What must be done to solve the problem?
function analysis inventory of the data elements data dictionary logical model of the system ( data analysis ) major algorithms
compose the working groups planning per department
Design : Detailed
- interfaces with other systems
- controls and checking
- privacy and security aspects
- hardware specifications
- job flow design
- Physical database design
- high-level program design
Detailed system and design specification
Programming and Implementation
Program designdiagramscodetests
documentation data conversion procedure development user training
- Program specifications- Code
- Program specifications- Code
- User documentation
- Operations documentation
- User documentation
- Operations documentation
Installation
Installation of the hardware Install security procedures Tests in operational environment Training operations department Take-over in user department and EDP-
department Operational
Post-implementation
AUDIT compare actual system with projected budget and
timing evaluate actual operation cost evaluate user satisfaction evaluate security
MAINTENANCE establish hardware maintenance procedures test security plan establish change management procedures