Waterfall Model

Waterfall Model

1. Features

   • Sequence of distinct phases
   • 1 stage must be finished before moving onto a next phase
   • Deliverables at end of each stage used to ensure progress
   • If error is found during a stage then previous stages may need to be reworked

2. Stages

   • Analysis
     • Help Systems Analyst define requirements
     • Questionnaire
     • Observation
     • Interview
     • Document Inspection
     • Discover the data, volume of data, information, users & roles, problems with current system
   • Design
     • Solution defined
     • Data to be processed specified
     • Input, Processes & Format of Output defined
     • Hardware & Software requirements
     • Testing strategies defined
   • Development & Testing
     • Unit Testing
       • Testing each field, button etc. for validation
       • Person who wrote code
     • Integration Testing
       • All code functions together
       • Construction Team
     • System Testing
       • Actual data if used in real situation
       • Under supervision of Systems Analyst
     • Types of Test Data
       • Extreme
         • On Boundary
       • Valid/ Normal
         • Within Boundaries
       • Exceptional
         • Doesn't follow rules but valid e.g. 29th February
       • Invalid/ Erroneous
         • Not Acceptable
   • Implementation
     • Parallel
       • Old & New side by side
       • Safer
       • More work
     • Phased
       • Part I complete before Part 2
       • Safer
       • Long
     • Direct
       • New system starts on set day
       • Faster
       • Stressful, No fall back
     • Pilot
       • Installed in one branch
       • Train other staff, identify problems
       • Takes Time
   • Review & Maintenance
     • Corrective
       • Small issues after installation
     • Adaptive
       • Due to external factors e.g. VAT change
     • Perfective
       • System in place for some time but some small tweaks identified