Solution

Top-Down and Bottom-Up Design

Top-Down:

• Start from top-level system → decompose into subsystems/modules → detail. Like breaking overview into parts.
• Tools: Structure chart, stepwise refinement.
• Pros: Early overview, architecture clear
• Cons: Low-level details delayed, needs stubs for testing
• Ex: Design Online Exam → split into User, Exam, Evaluation modules

Bottom-Up:

• Start from bottom-level components → combine into higher system. Build reusable parts first.
• Pros: Reuse, early component testing via drivers
• Cons: No system view early, integration complex
• Ex: Build DB, utility libraries first → integrate into system

Hybrid: Most projects use both - Top-down for architecture, Bottom-up for building reusable components. Combined gives Sandwich/Hybrid testing.