Project Life Cycles System development life cycle Waterfall

Project Life Cycles

System development life cycle • Waterfall model • Spiral model • Whirlpool model • Rugby model • OMG model

Waterfall model Project proposal report project definition Functional specifications Feasibility report system study design specifications program specifications code programming system performance tests Installation - intermediate reports - go/nogo intervals Post Implementation audit , feed-back

Boehm’s Spiral Model progress through steps determine objectives, alternatives constraints Risk Analysis evaluate alternatives identify , resolve risks Risk Analysis requirements plan life cycle plan integration tests and plan Risk operational Analysis prototype 2 prototype 1 simulation models Benchmarks concept of operation Software design Design detailed design validation and verification coding Plan next phases Prototype based integration tests implementation

Whirlpool model project definition Project proposal report system study Functional specifications Feasibility report design specifications program specifications code programming system performance tests Installation Post Implementation 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: ð The analyst knows everything and understands the problem completely before implementation starts ð The users read the system analysis report and approve it

OMG-model (Object Management Group ) Facts: ð System requirements are not fully known at the start ð knowledge of the system grows during development ð better develop a system incrementally ð start with some core functions analysis object modelling design construction coordination and reuse full system definition

OMG Project Management ð Iterative style develop a series of solutions to a problem , each of them closer to satisfying the requirements ( also called : evolutionary development ) ð Incremental style Builds 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 Project proposal report project definition Functional specifications Feasibility report system study design specifications program specifications code programming system performance tests Installation - intermediate reports - go/nogo intervals Post Implementation audit , feed-back

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: 1. Activities: Top-down technique 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: ð form ð point of time and frequency ð origin ð responsibility For the output: ð type and layout ð point of time and frequency ð destination ð usage Furthermore: ð reasons for realization ð financial advantages ð constraints and borders of the system

System study : The feasibility study Responsibility from this phase on in the ICT-department ð study of the existing system ð borders of the new system ð links with other systems ð study of different solutions ð division in subsystems ð applicability of packages ð estimation of personnel requirements ð cost-benefit analysis The report allows the steering committee to: - fix timings - final decision

Design : general § What must be done to solve the problem? ð function analysis ð inventory of the data elements ð data dictionary ð logical model of the system ( data analysis ) ð 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 design ðdiagrams ðcode ðtests § § documentation data conversion procedure development user training - Program specifications - Code

Installation § § § Installation of the hardware Install security procedures Tests in operational environment Training operations department Take-over in user department and EDPdepartment Operational - User documentation - Operations documentation

Post-implementation AUDIT ð compare actual system with projected budget and timing ð evaluate actual operation cost ð evaluate user satisfaction ð evaluate security MAINTENANCE ð establish hardware maintenance procedures ð test security plan ð establish change management procedures