Iterative Development

Iterative Development

1. It gets much more expensive to fix problems later

2. Never ending cycle of:

   • Determining objectives, alternatives, constraints
   • Evaluate Alternatives and Resolve Risks
   • Develop and Verify Next Level Product
   • Plan next phases

3. Prototypes

   • Support early investigation and early problem-finding
   • Can simulate incomplete components
     • But not random/time-dependent behaviour
   • Allows early interaction with clients, even at inception phase
   • Emphasise appearance of the interface
     • simulate behaviour with "scripting"
   • Cheap prototypes are good, make them disposable
   • Paper and pen is good for early versions, can simulate behaviour by change "screen" by pointing at "buttons" and having the demonstrator change the slide
   • Wizard-of-Oz
     • Have an out of sight experimenter recreate behaviour
     • Cheaply assess effects of so called intelligent interfaces

4. Versioning

   • major.minor.patch
     • major version when you make non-backward compatible changes
     • minor version when you add functionality in a backwards compatible manner
     • patch version when you make only bug fixes

5. Agile Methods

   • Deliver working software from outset
   • Collect user stories describing requirements
   • Design leader prioritises implementation
   • Build functional increments in sprints
   • Refactor as required
   • Stop when money runs out
   • There is some tension with user-centred processes
   • Extreme Programming
     • Software development is a collaborative process
     • Customers work with developers onsite
     • Coach as opposed to project manager
     • Use user stories
     • Timeboxing of releases
     • TDD
     • Pair-Programming
     • A simple daily stand up for team awareness
   • Scrum
     • Project Roles
       • Product owner
       • Development Team
       • Scrum Master
     • Managed Backlog
     • timeboxed sprints
   • Participatory Design
     • users become partners in design team
     • PICTIVE method
       • users generate scenarios in advance
       • collaborative session with pens and paper
       • videotape session for data analysis
     • CARD
       • Cards with screen shots on are arranged on a table to explore workflow options