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Lessons (20)

• Consumers & Consumer Groups

  How consumers read in parallel with consumer groups, how partitions are assigned and rebalanced, how offsets are committed …

• What Is Apache Kafka?

  … 8997 }) }], }); // Consumer: read events as part of a group const consumer = kafka.consumer({ groupId: "email-service" }); await consumer …

• Delivery Guarantees: At-Most, At-Least & Exactly Once

  … when the producer writes it, and when the consumer processes it. mermaid flowchart LR P[Producer] -- "① ack …

• Message Queues & RabbitMQ

  … Learn producers, consumers, acknowledgements, exchanges, retries and dead-letter queues with RabbitMQ. The big idea At a busy …

• Event-Driven Architecture

  … Event-carried state transfer The data consumers need { type: "CustomerMoved", customerId, newAddress } Consumers keep a local copy and …

• Real-Time, Pub/Sub, Webhooks and CDC

  … an event stream can feed pub-sub consumers, webhook delivery, server-sent updates and database change capture](/img …

• Kafka vs RabbitMQ & the Kafka Ecosystem

  … topic + partition by key Ordering Per queue (with one consumer) Per partition Throughput High (tens of thousands of …

• Topics, Partitions & Offsets

  … Compacted topics are great for restoring state (Kafka itself stores consumer offsets in a compacted topic, consumer offsets …

• Hexagonal Architecture (Ports & Adapters)

  … controller] CLI[CLI command] Test[🧪 Test] Consumer[Kafka consumer] end subgraph Core["⬡ Application core"] IP{{"Driving port …

• Data in Microservices: Sagas & the Outbox Pattern

  … If the relay crashes after publishing but before marking the row, the event is published twice, so consumers …

• Deploying & Operating Microservices

  … Remember to delete old flags, or they become technical debt. Never break your consumers Other services depend on …

• Service Communication: Sync vs Async

  … Interested services consume it when they're ready. mermaid sequenceDiagram participant C as Client participant O as Orders …

• Kafka Producers

  … But producers and consumers must agree on it. Format Pros Cons --- --- --- JSON Human-readable, easy Larger, no enforced …

• Scaling & Health Probes

  … scale consumers on Kafka lag triggers: - type: kafka metadata: bootstrapServers: kafka:9092 consumerGroup: email-service topic: shop.orders …

• Timeouts, Retries & Backpressure

  A slow dependency should consume a bounded budget, not create an infinite retry storm. The big idea A …

• Brokers, Replication & Durability

  … It stores partition replicas and serves producers and consumers. - A cluster is a group of brokers (3 at …

• State Management (Redux, Zustand, TanStack Query)

  … Very low Medium Low Re-render control ❌ All consumers ✅ Selectors ✅ Selectors ✅ Per query DevTools ❌ ✅ ✅✅ ✅ Learning curve Easy Easy …

• Scaling, Load Balancing & Rate Limiting

  … resource pools, so one slow dependency can't consume every thread Graceful degradation Show cached or partial results …

• Caching & Redis

  … time windows Stream XADD , XREADGROUP Event log with consumer groups Pub/Sub PUBLISH , SUBSCRIBE Real-time notifications, chat …

• Domain-Driven Design: Strategic Design

  … a well-defined public API for everyone Many consumers Published Language A documented shared format (schemas, events) Paired …