Shortcomings of software development models

Shortcomings of existing models

• Waterfall: rigid and sequential; requirements must be fixed at the start; a working product appears late; errors found late are expensive; poor for changing requirements.
• Prototyping: the customer may confuse the prototype with the final product; quick-and-dirty design; unplanned iterations raise cost and time; poor documentation.
• Spiral: needs expert risk analysis; costly and complex to manage; not suitable for small, low-risk projects; hard to define end of the loops.
• General: weak customer involvement during development, heavy documentation, difficulty of estimating, insufficient support for reuse and for hardware/software co-design in embedded systems.

Measures to overcome them

1. Hybrid or iterative-incremental approach: a waterfall-style plan for stable parts, with prototyping for unclear parts and spiral-style risk analysis for critical parts; deliver in increments.
2. Agile practices: short iterations, continuous customer feedback, frequent builds and adaptive planning.
3. Early validation: requirement reviews, prototypes of user interface, simulation.
4. Risk management from the start, with regular reviews.
5. Configuration and change control to manage changes; maintain essential documentation and traceability.
6. Continuous integration and automated testing to find bugs early; reuse of tested components.