README.md

SCS-100

PubSub Mechanism

A simple Example of an Event Driven Flow by the help of SPRING CLOUD STREAM KAFKA

properties

• java.version: 11
• spring-cloud.version: Hoxton.SR12 (To get Advantage of Binders @Input,@Output)
• spring-boot.version: 2.4.13

Documentation

Please visit Spring Cloud Stream Kafka (Part 2) for Project documentation

The Docker-compose file contains: single kafka and zookeeper. just simply run the following command

docker-compose up -d

or

• Control Center UI Runs a Confluent Control Center that exposes a UI at http://localhost:9021/ .

docker-compose -f ./kafka-cluster.yml -f ./control-center-ui.yml up

To stop the brokers and the Control Center UI run the following command:

docker-compose -f ./kafka-cluster.yml -f ./control-center-ui.yml down

I assume you already have docker setup in your machine.

Make the project

run the following command line to create you jar file in target directory

mvn clean package

Then run the generated jar file in target folder, (so make sure you are in the same directory when you run the jar file or give the full path)

java -jar scs-100-0.0.1-SNAPSHOT.jar

the application starts to listen on port 8080. make sure that port not being occupied by any other app already, if is try to pass the following parameter before -jar by adding -Dserver.port=8081 as:

java --server.port=8081 -jar target/scs-100-0.0.1-SNAPSHOT.jar

or

mvn spring-boot:run -Dserver.port=8081

you can also modify the application.yml and set the same properties based on your app profile

At this point you should have already seen the information about your topics.

Check Application

Create Order or Place your Order

you should now be able to place your order by calling the following curl command

# assuming your app is listening on 8080
ORDER_UUID=$(curl --silent -H 'Content-Type: application/json' -d "{\"itemName\":\"book\"}" http://localhost:8080/order | jq -r '.orderUuid') && for i in `seq 1 15`; do echo $(curl --silent "http://localhost:8080/order/status/"$ORDER_UUID); sleep 1; done;

make sure you have already installed the jq

Next

Please visit Spring Cloud Stream Kafka (Part 2) for Project documentation

⚠ NOTE: Starting with spring-cloud-stream-binder-kafka/spring-cloud-starter-stream-kafka 3.0, when spring.cloud.stream.binding.<name>.consumer.batch-mode is set to true, all of the records received by polling the Kafka Consumer will be presented as a List<?> to the listener method. Otherwise, the method will be called with one record at a time. The size of the batch is controlled by Kafka consumer properties max.poll.records, fetch.min.bytes, fetch.max.wait.ms; refer to the Kafka documentation for more information.

Bear in mind that batch mode is not supported with @StreamListener - it only works with the newer functional programming model. reference: https://docs.spring.io/spring-cloud-stream-binder-kafka/docs/current/reference/html/spring-cloud-stream-binder-kafka.html#pause-resume

Spring Cloud Stream - functional and reactive

• Spring Cloud Function
• Cloud Events and Spring - part 1 (Oleg Zhurakousky)
• Cloud Events and Spring - part 2 (Oleg Zhurakousky)
• Spring Cloud Stream - demystified and simplified
• Spring Cloud Stream - functional and reactive (Oleg Zhurakousky)