System Design Case Studies

System design requires decisions across service boundaries, data ownership, consistency, and failure recovery. These case studies establish concrete system contexts and the requirements and trade-offs that shape their architectures.

• Payment System — Payment correctness under retries, uncertain outcomes, and provider failures.
• Notification System — Delivery across channels with provider limits, user preferences, and duplicate processing.
• Distributed Cache — Partitioning, replication, eviction, and recovery under node failure.
• Order Management — Coordination across inventory, payment, shipping, and fulfillment.

The current pages define the design scenarios and key considerations; they do not present completed implementations or measured production results.