Getting Started

Preliminary steps

1. Start docker desktop

2. In a terminal from the root directory of the project run docker compose -f ./docker-compose.yml up -d. Use docker compose -f ./docker-compose.yml start if containers have been already created

3. Once all the containers are up and running execute the command docker exec broker kafka-topics --bootstrap-server broker:29092 --create --topic messages-avro-topic to create the kafka topic

4. Run docker exec -it schema-registry bash

5. The prompt [appuser@schema-registry ~]$ comes up

6. Type the following command to publish avro records into the topic
   kafka-avro-console-producer --bootstrap-server broker:29092 --topic messages-avro-topic --property parse.key=true --property "key.separator=;" --property key.schema='{"type":"record","name":"message_key","fields":[{"name":"sender","type":"string"}, {"name":"sequence","type":"string"}]}' --property value.schema='{"type":"record","name":"message_value","fields":[{"name":"text","type":"string"}]}' --property schema.registry.url=http://localhost:8081

   Once started, the process will wait for you to enter messages, one per line (no prompt, just a blank line), and will send them immediately when you hit the Enter key.
   Here are 3 examples
   {"sender": "Pete", "sequence": "1"};{"text": "Hi"}
   {"sender": "Pete", "sequence": "2"};{"text": "Hello"}
   {"sender": "Roger", "sequence": "1"};{"text": "Good bye"}

7. Exit the process with Ctrl+C

8. Quit the schema-registry shell running the exit command

9. Type docker exec -it ksqldb-cli ksql http://ksqldb-server:8088 to create a stream linked to the topic

10. From the ksqldb> prompt run CREATE STREAM messages (SENDER VARCHAR KEY, SEQUENCE VARCHAR KEY) WITH (KAFKA_TOPIC = 'messages-avro-topic', KEY_FORMAT = 'AVRO', VALUE_FORMAT = 'AVRO');

11. Run select * from messages; just to check that the 3 records published to the kafka topic are in the stream too

Run the web application

1. Start the application running the command ./mvnw spring-boot:run
2. Open a new terminal and run curl -v http://localhost:8080; you will get 3 records previously published to the topic
3. Execute the command docker compose -f ./docker-compose.yml -p ksqldb-demo stop if you want to reuse generated sample data or docker compose -f ./docker-compose.yml down if you don't need to

./mvnw native:compile -Pnative -DskipTests