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Prescriptive Software Models. Recall Boehm’s paper. Why did they “invent” the waterfall model? Distinction between programmer and user Increased application, higher risks Large systems: development is a group activity Bring order to chaos:
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Recall Boehm’s paper • Why did they “invent” the waterfall model? • Distinction between programmer and user • Increased application, higher risks • Large systems: development is a group activity • Bring order to chaos: • Increased system and company size requires a design phase • Different end users demands a requirements phase • Need for quality demands an orderly approach
Prescriptive models • Several variants of the waterfall model exist • All depend on stable requirements • All focus on deliverables and documentation • These models are still popular today • For contracts that require documentation (DoD, government, etc) • For large systems with many developers • But they frequently “fail” • What are the benefits and drawbacks of each?
Types of Prescriptive Models • Waterfall
Types of Prescriptive Models • Incremental
Types of Prescriptive Models • Rapid Application Development (RAD)
Types of Prescriptive Models • Evolutionary models: spiral
Types of Prescriptive Models • Prototyping
Types of Prescriptive Models • Unified Process Model
In-class exercise • Which prescriptive model would you use to: • Developing software to automatically drive racecars through a track without crashing. This has never been attempted before under software control. The requirements are stable. • Developing software to track the financial bailout. The software requirements are very clear. You need to create a system to perform 3 distinct tasks. All functions will interface with each other and the same underlying database.