• Java 17
• Spring Webflux
• R2DBC + PostgreSQL
• Kafka

1. Start Kafka + PostgreSQL and the actual backend service using docker-compose up

OR

1. Start Kafka + PostgreSQL using docker-compose -f docker-compose-dependencies.yaml up
2. Run the service yourself with you favourite IDE or with ./gradlew bootRun

Then the web socket is reachable at ws://localhost:8080/chat

Hi there, it was "hinted" to split WS and message logic, I've decided to use a single backend service in order to have only one service reading and writing on the same database, avoiding breaking microservices best practices. Basically the service is both the producer and consumer of the Kafka queue, but that still improves availability and being able to handle high-traffic or delay some operations (database message storage). I'm open to discussions.

The app is built in a reactive / async manner providing functional web-socket logic, kafka and database management.

1. Depending by the dockerised gradle build and the Kafka partition setup, the application can be kinda slow. I have not spent time on this as any real app will have it's own CI/CD setup to run the app
2. WebSockerHandler in a functional style leads to some complexity
3. R2DBC drivers and libraries still have major bugs