scs-100-2

SCS-100-2

Functional Programming (For Alternative of SCS-100 Project)

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

properties

• java.version: 11
• spring-cloud.version: 2020.0.3
• spring-boot.version: 2.5.2

Documentation

Please visit Spring Cloud Stream Kafka (Part 3) for Project documentation

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

docker-compose up -d

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.

To scale the application horizontally you can add the following parameter before -jar by adding -Dserver.port=8081 (basically a different port) as:

java -Dserver.port=8081 -jar scs-100-0.0.1-SNAPSHOT.jar

When you running multiple instances of the same application on a single machine, this path must be unique for each such instance. At this point you should have already seen the information about your topics , to read more

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 sleep 1; echo $(curl --silent "http://localhost:8080/order/status/"$ORDER_UUID); done;

Note: make sure you have already installed the jq

Running Multi Instances

Now let’s run the same application multiple times at the same time to simulate the application redundancy. But before that make sure that the current application is not running.

This project code comes with Nginx as LoadBalancer which has already been configured to distribute the incoming traffic from port 8080 and route it into 8081 and 8082.

So first let’s start it in different docker-compose from root on this project “scs-100-2” as:

docker-compose -f nginx/docker-compose.yml up -d

Since the port 8080 is already got occupied by nginx we can run the Ordering application as follow in 2 separated terminal

Terminal 1:

java -Dserver.port=8081 -jar target/scs-100-2-0.0.1-SNAPSHOT.jar

And on Terminal 2:

java -Dserver.port=8082 -jar target/scs-100-2-0.0.1-SNAPSHOT.jar

Then run our curl call command again (same as the earlier one)

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 sleep 1; echo $(curl --silent "http://localhost:8080/order/status/"$ORDER_UUID); done;

Please visit Spring Cloud Stream Kafka (Part 3) for Project documentation