FIELD NOTES / SENIOR BACKEND & FINTECH
Begin with commands, events, and guarantees. Learn the AWS mechanics, apply them to financial systems and the repository case study, then prove the cost, recovery, and operational boundaries. Every chapter below is part of the guide; the study guide explains prerequisites, service coverage, and the checkpoint for each stage.
01Event-driven foundationsDefine commands, facts, work ownership, ordering, and the separate delivery, processing, and business-effect boundaries.↗02AWS messaging and compute decisionsChoose queues, routers, retained streams, workflow orchestration, and compute from explicit workload and recovery requirements.↗03Kinesis: partitioning, consumers, and replayConnect partition-key order to producer results, consumer checkpoints, hot keys, retention, and safe backlog recovery.↗04DynamoDB: access patterns and authorityDesign keys and indexes from access patterns, protect exact financial state with transactions and durable identity, and plan complete rebuilds.↗05CQRS, event sourcing, outbox, and sagasSeparate read optimization, authoritative history, publication intent, and cross-service coordination without combining their guarantees.↗06Reliability, correctness, and recoveryAssign retry ownership, retain failure evidence, protect live capacity, reconcile exact outcomes, and recover one fenced writer.↗07Fintech and trading architectureConnect order acceptance, reservations, execution, clearing, settlement, ledger postings, and derived views into explicit authority boundaries.↗08Apply the design to the repositoryUse concrete code evidence to diagnose publication gaps, duplicate effects, unsafe money, incomplete exports, and missing financial controls.↗09Cost, performance, and capacityRecompute complete unit costs and capacity using dated inputs, rounding, fan-out, hot-lane distribution, recovery load, and ownership costs.↗10Observability, security, and operationsTranslate business outcomes into measurable SLOs, actionable alarms, scoped access, evidence retention, compatible releases, and recovery exercises.↗11Interview practice and self-assessmentCombine service selection, failure analysis, quantitative reasoning, system design, and repository review into defensible spoken answers.↗
Carry one accepted order through each chapter. After the examples, close the notes and explain who owns the truth, what can fail, and what evidence proves recovery. The final interview drills bring service selection, failure analysis, arithmetic, system design, and repository reasoning together.
Use the quick reference for recall and the source index for evidence. Full chapters, dated claims, worked models, and byte-identical originals remain available throughout.