Chapter 10 — Layered Architecture Style

Core ideas

• Technically partitioned, monolithic, the “default.” Layers: presentation → business → persistence → database. Each layer has a role/responsibility.
• Layers of isolation: changes in one layer don’t affect others.
• Closed vs. open layers and the architecture sinkhole anti-pattern (requests passing straight through layers doing nothing — if >~20% of requests are sinkholes, reconsider).
• Ratings: great cost/simplicity, weak scalability/elasticity/deployability/evolvability.

Trade-offs / when to use

Small/simple apps, tight budgets, or as a starting point. Avoid when you need independent scaling or fast, frequent deployments.