System Design Deep Dive
Learner applies system design to payments, covering throughput, latency, idempotency, exactly-once processing, and failure recovery, and designs a system for a stated load. Learner practises this skill on realistic banking cases, explaining the reasoning clearly and using correct terminology throughout the work.
System design deep dive: how payment systems are architected inside banks.
What You Can Do After This Chapter
Learning objective. Learner applies system design to payments, covering throughput, latency, idempotency, exactly-once processing, and failure recovery, and designs a system for a stated load. Learner practises this skill on realistic banking cases, explaining the reasoning clearly and using correct terminology throughout the work.
Practical assessment. Learner designs a payment system handling 1,000 transactions per second with a 2 second latency target, covering intake, validation, deduplication, and settlement. Learner then explains how idempotency prevents a duplicate 500 dollar charge after a retry, and draws the failure recovery flow when the settlement module goes down mid-batch. Learner presents the work with calculations and assumptions stated clearly, then reviews it against the chapter checklist and corrects any gaps before submission.
Expected deliverables.
- System design diagram for 1,000 transactions per second
- Idempotency design explainer
- Failure recovery flow diagram
- Throughput and latency calculation sheet
Completion criterion. Learner designs for the stated load with deduplication and recovery, explains idempotency correctly, and shows a workable recovery flow for the outage. Judgement covers accuracy, completeness, and clear written explanation in the submitted work.