We've included the full sample project here for you to play with.
You'll need to have docker installed for this exercise. Run this to start up postgres:
./start-local-test-db.sh
Then start up a Kafka instance
in the kafka/ folder (at the root of this workshop), run:
docker-compose up
Start Quarkus in dev mode
./mvnw quarkus:dev
keep this running in a separate terminal window throughout this exercise!
Create a new Article, which will send a message to a Kafka topic - see ArticleResource.java.
curl -H "Content-type: application/json" -d "{\"title\":\"Kafka test\", \"asciidocsource\":\"https://somesource/\"}" -X POST http://localhost:8080/article
There's a consumer in EmailGenerator.java that prints out what is being read from the topic.
The ArticleResouce class sends the message - have a look at its setup. There is an Emitter that provides a Java service object into Kafka.
Look at the terminal window where you started Quarkus and you'll see the output:
Received message on Kafka topic 'emails':
Now change the ArticleResource and customize the message payload on this ine:
emails.send("Send an email for article with id:" ...
To send a different message. Then create another Article using the curl command above... note how we still have hot reloading enabled, even for this project that integrates with Kafka!
Have a look at the application.properties file to see how all this is setup!
Follow this guide to get learn how to implement Kafka Streams and processing in Quarkus:
https://quarkus.io/guides/kafka-streams
Write unit tests using Kafka TestContainers! Have a look at the KafkaEnvironment.java to help you get started.