Kafka messaging
Studies in this cluster, in series order. Each one keeps its own URL.
Messaging
Kafka, event-driven architecture, outbox and CQRS, WebSockets, MQTT, and queues you can defend in interviews.
Kafka messaging
5 studies- 1.Apache Kafka — Topics, Partitions, Brokers & Consumer GroupsAppend-only partitioned logs; consumer group assigns each partition to at most one member; durability=ISR; scale=partitions; order=within partition.
- 2.Partition Keys — Ordering Guarantees vs Parallel Throughputhash(key)%N sticky order; null keys sticky/RR; repartition breaks affinity; hot keys/sticky partitioner.
- 3.Delivery Semantics — At-Least-Once, At-Most-Once & Exactly-OnceAMO vs ALO vs EOS (idempotent producer+transactions); external side effects still need idempotency keys.
- 4.Consumer Rebalancing, Lag & BackpressureCooperative sticky vs eager; lag as offset gap; pause/resume; scale consumers vs partitions.
- 5.Schema Evolution, Compatibility & Dead Letter QueuesAvro/Protobuf/JSON Schema; FORWARD/BACKWARD/FULL; poison→DLQ/retry; never block forever on bad payload.