1.2.3 software development

• Waterfall cycle

  • stages are completed in sequence, from start to finish
  • clear structure makes this a model that is easy to follow
  • low user involvement
• Agile methodologies

  • Collection of methodologies which aim to improve the flexibility of SDLCs
  • Adapt quickly to changes in user requirements
  • Working prototype is delivered early on and improved in an iterative manner
  • Less of a focus on documentation
  • User satisfaction is prioritised
• Extreme programming

  • Example of an agile model
  • Development team is a pair of programmers and a representative end user
  • Produces high quality code and highly usable software
  • Hard to produce high quality documentation
• Spiral model

  • Used to manage risk heavy projects
  • Project terminate if too risky
  • Specialist risk assessors must be hired which is expensive
• Rapid application development

  • Iterative methodology which uses partially functioning prototypes
  • User requirements are gathered using focus group
  • User feedback is used to generated next, improved prototype
  • Final prototype matches user requirements fully
  • Code may be inefficient
• Algorithms are a set of instructions used to solve a problem
• Algorithms

  • inputs must be clearly defined
  • must always produce a valid output for any defined input
  • must be able to deal with invalid inputs
  • must always reach a stopping condition
  • must be well documented for reference