I just published a new video where I take you behind the scenes of building a real-time event processing application using Spring Boot and Kafka Streams.

🛠️ In this video, I cover:

✅ Designing a clean, modular Kafka Streams topology

✅ Using Serde for JSON serialization of domain objects

✅ Extracting logic into a service layer and helper classes

✅ Keeping configuration and business logic separate

✅ Writing unit tests with JUnit 5 and Mockito

✅ Fixing tricky test execution errors (NoSuchMethodError, missing artifacts)

✅ Understanding when to use @Bean vs @Service for stream startup

🧭 The app processes visit events across Lille city 🏙️ and routes them to different Kafka topics based on a timetable validation logic.

📹 Watch the full video here:

👉 https://youtu.be/s07d3SmoBMI

🔗 If you're building streaming apps or exploring event-driven architecture with Spring, I think this will help you a lot.

Let me know what you think—and feel free to share with anyone working on real-time data systems! 🙌

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