A Practical Guide

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Sending a message to Kafka takes five lines of code. Building a reliable event-driven system takes much more.

The hard part is everything around that first message: choosing keys so events stay in order, making consumers survive rebalances without double-processing, evolving schemas without breaking other teams, handling poison messages, publishing events consistently with your database, getting exactly-once results where money is involved, processing streams in real time, and running the cluster securely in production.

This book shows you how to get all of it right — step by step, with one realistic running example: Brightvault, a digital bank with card authorizations, real-time fraud detection, transfers, a double-entry ledger, instant notifications, and a legacy core-banking system replaced through change data capture.

• 457 pages · 28 chapters + 4 appendices
• Event modeling: events vs. commands vs. messages, envelopes, and naming
• Kafka architecture: brokers, partitions, replication, ISR, and KRaft
• Producers and consumers in depth: batching, acks, idempotence, consumer groups, offsets, rebalancing, and lag
• Avro, Protobuf, JSON Schema, schema registries, and safe schema evolution
• Topic design: keys, partition counts, retention, and log compaction
• Delivery semantics, transactions, and exactly-once processing
• Retries, dead-letter topics, idempotent consumers, and ordering guarantees
• Transactional outbox and change data capture with Debezium and Kafka Connect
• Kafka Streams: KStream, KTable, aggregations, windowing, joins, and state stores
• Choreography vs. orchestration, sagas, event sourcing, CQRS, and the strangler fig
• Testing, operations, monitoring, security, quotas, and multi-region replication

Table Of Contents

Part I — Event-Driven Foundations

• Ch 1 · Why Event-Driven Architecture: From Request/Response to Streams of Events
• Ch 2 · Events, Commands, and Messages: Modeling What Happened
• Ch 3 · Kafka Architecture: Brokers, Topics, Partitions, Replication, and KRaft
• Ch 4 · Getting Started: Running Kafka Locally and Using the Command-Line Tools
• Ch 5 · Your First Event Flow: Producing and Consuming Brightvault Card Events

Part II — Producers, Consumers, and Data Contracts

• Ch 6 · Producers in Depth: Batching, Acknowledgments, Idempotence, and Ordering
• Ch 7 · Consumers in Depth: Consumer Groups, Offsets, Rebalancing, and Lag
• Ch 8 · Serialization and Schemas: JSON, Avro, Protobuf, and Schema Registry
• Ch 9 · Schema Evolution and Data Contracts
• Ch 10 · Topic Design: Keys, Partition Counts, Retention, and Log Compaction

Part III — Delivery Guarantees and Reliability

• Ch 11 · Delivery Semantics: At-Most-Once, At-Least-Once, and Exactly-Once
• Ch 12 · Kafka Transactions and Exactly-Once Processing
• Ch 13 · Error Handling: Retries, Dead-Letter Topics, and Poison Messages
• Ch 14 · The Transactional Outbox and Change Data Capture with Debezium
• Ch 15 · Idempotent Consumers, Deduplication, and Ordering Guarantees

Part IV — Stream Processing and Integration

• Ch 16 · Kafka Streams Fundamentals: Topologies, KStream, and KTable
• Ch 17 · Stateful Processing: Aggregations, Windowing, and State Stores
• Ch 18 · Stream Joins and Enrichment: Real-Time Fraud Detection
• Ch 19 · Kafka Connect: Integrating Databases, Object Storage, and Search
• Ch 20 · Beyond Kafka Streams: Apache Flink, ksqlDB, and Choosing a Stream Processor

Part V — Event-Driven Architecture Patterns

• Ch 21 · Event-Driven Microservices: Choreography vs. Orchestration
• Ch 22 · Sagas and Long-Running Business Processes
• Ch 23 · Event Sourcing and CQRS with Kafka
• Ch 24 · Integration Patterns: Webhooks, APIs, Legacy Systems, and the Strangler Fig
• Ch 25 · Testing Event-Driven Systems

Part VI — Operating Kafka in Production

• Ch 26 · Operating Kafka: Sizing, Monitoring, Tuning, and Upgrades
• Ch 27 · Security, Multi-Tenancy, and Multi-Region: TLS, SASL, ACLs, Quotas, and Replication
• Ch 28 · Case Study: Building the Brightvault Event Platform End to End

Appendices

• App A · Kafka Cheat Sheet
• App B · Templates and Configuration Reference
• App C · Production Checklist
• App D · Glossary

WHO IT IS FOR
Backend developers starting with Kafka who want to understand it properly, engineers building event-driven microservices, architects choosing patterns such as sagas, event sourcing, and CQRS, and platform engineers who run Kafka in production. Examples use Java 21 and the official Kafka clients.

FORMAT
PDF (A4), 457 pages, English, clickable table of contents and PDF bookmarks. 1st Edition, 2026. Published by thenexbooks.

This book is independent and is not affiliated with or endorsed by The Apache Software Foundation, Confluent, or any other company. Apache Kafka, Kafka, and Apache Flink are trademarks of The Apache Software Foundation. Brightvault and all examples are fictional.

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