spring-kafka-demo

Event-Driven Architectures for Spring Developers

Overview

This repo contains 3 Spring Boot projects

• update-currency - A REST application for updating currency conversion rates: It uses Spring JPA and will auto-create the schema for the currency table; the application.properties are configured to use a database named cdc.

• listener - Receives change events from MySQL via Zendesk Maxwell and a Kafka topic maxwell and forwards currency changes to compacted topic currency. Deletions are forwarded as tombstone records.

• currencyreader - Receives currency events and stores them in a map for instant use within the application. Java and Kotlin versions are provided.

Setup

Install MySQL and Maxwell (I used homebrew on Mac OS).

I had some [authentication issues with MySQL 8, documented here](zendesk/maxwell#1232).

my.cnf

server_id=1
log-bin=master
binlog_format=row
default-authentication-plugin=mysql_native_password

CREATE USER 'maxwell'@'localhost' IDENTIFIED WITH 'mysql_native_password' AS 'maxwell';

Running

Run maxwell

$ maxwell --user maxwell --password maxwell --producer=kafka --kafka.bootstrap.servers=localhost:9092 --kafka_topic=maxwell

Run all three boot applications and post a few currency updates:

$ curl -X POST http://localhost:8091/update/USD/1000

$ curl -X POST http://localhost:8091/update/GBP/782

$ curl -X POST http://localhost:8091/update/EUR/800

$ curl -X POST http://localhost:8091/delete/EUR

Observe the console of the currencyreader application.