Software Development- waterfall model and RAD

Software Development- waterfall model and RAD

1. WATERFALL LIFE CYCLE MODEL

   • Each step is completed at a time from start to finish
   • Each step/ stage must be completed before you can move onto the next one
   • Better used for smaller projects because the requirements are well known-and any changes would mean that you can easily jump back to the previous stage
   • Stages of the life cycle:
     • 1. REQUIREMENTS- expectations and goals of the project are defined in this stage. System analysts do this.
     • 2. DESIGN- after the goals have established, work commences on designing the product and plans are made.
     • 3. CONSTRUCTION- the software/code for the project is written
     • 4. TESTING AND DEBUGGING- software is tested to make sure is meets the client's requirements
     • 5. INSTALLATION- product is implemented according to the agreed reuirements
     • 6. MAINTENANCE- the product is sent to the client and support of the product is put into place
   • ADVANTAGES
     • Well suited for projects where quality is emphasised over cost or time-requirements
     • Lack of any overlap between phases avoids confusion
     • High visibility-demonstrate output can be seen
   • DISADVANTAGES
     • Not suitable for large-scale projects
     • Changes in requirements later in the stage may take longer to create as you have to go back to the original stage
     • Not suited for the fast changing computers in today's world. Software may not work on different computers

2. RAD- rapid application development

   • Emphasising rapid prototyping and iterative delivery.
   • Produces successive prototypes of the software
   • Rigidly placed schedule that defers design improvements to the next product
   • MAIN STAGES OF RAD
     • Make of improve a prototype
     • Evaluate the prototype
     • Repeat until the job is done
   • ADVANTAGES
     • User involvement- the user can use the software and give feedback on a live system-so no time will be waster going back to the design level as you do it as you go along
     • Errors will be found much earlier on in the stage
   • DISADVANTAGES
     • Requires highly skilled programmers and designers
     • Only a system that can be modulised can use RAD