1.2.3

• Programming methodologies


  • Waterfall lifecycle
  • Agile methodologies
  • Extreme programming
  • Spiral model
  • Rapid application development
• Waterfall lifecycle


  • Series of stages completed in sequence from start to finish
  • Includes a feasibility study (TELOS)
  • Changes require revisiting all levels between current and change stage
  • Users have little input
• Agile methodologies


  • Aim to improve flexibility and adapt to changing user requirements faster
  • Problem broken down into parallel sections
  • Design and analysis often occur together
  • Working prototype delivered early and improved iteratively
  • Less focus on documentation, more priority on user satisfaction
• Extreme programming


  • Agile model with pair programming and end-user representative
  • Uses 'user stories' to specify requirements
  • Aims to produce high-quality code
  • Programmers work no longer than 40 hours per week
  • Hard to produce high-quality documentation
• Spiral model


  • Focuses on effectively managing risk-heavy projects
  • Includes analysis, risk mitigation, development/testing/implementation, and evaluation
  • Project terminated if too risky
  • Hiring risk assessors can be expensive
• Rapid application development


  • Iterative methodology using partially functioning prototypes
  • User requirements initially gathered using focus groups
  • Incomplete prototype given to users to trial, feedback used to improve
  • Additions/changes may be inefficient as requirements change
• Algorithm


  Set of instructions used to solve a problem
• Qualities of good algorithms

  • Clearly defined inputs
  • Always produce valid output for defined input
  • Deal with invalid inputs
  • Reach stopping condition
  • Well-documented
  • Well-commented
• Merits of programming methodologies

  • Waterfall: Straightforward to manage, clearly documented
  • Agile: Produces high quality code, flexible to changing requirements, regular user input
  • Extreme Programming: Produces high quality code, constant user involvement for high usability
  • Spiral: Thorough risk-analysis and mitigation, caters to changing user needs, produces prototypes
  • Rapid Application Development: Caters to changing user requirements, highly usable finished product, focus on core features to reduce development time
• Drawbacks of programming methodologies

  • Waterfall: Lack of flexibility, no risk analysis, limited user involvement
  • Agile: Poor documentation, requires consistent interaction between user and programmer
  • Extreme Programming: High cost of two people working on one project, teamwork essential, end-user may not be able to be present
  • Spiral: Expensive to hire risk assessors, lack of focus on code efficiency, high costs due to constant prototyping
  • Rapid Application Development: Poorer quality documentation, fast pace may reduce code quality
• Uses of programming methodologies

  • Waterfall: Static, low-risk projects which need little user input, such as general-purpose software
  • Agile: Small to medium projects with unclear initial requirements
  • Extreme Programming: Small to medium projects with unclear initial requirements requiring excellent usability
  • Spiral: Large, risk-intensive projects with high budget
  • Rapid Application Development: Small to medium, low-budget projects with short time-frames