evrimulgen / springboot-kafka-websocket

The goal of this project is to implement two String Boot applications, bitcoin-api and bitcoin-client. The first simulates BTC price changes and the second, will listen from those changes and update an UI at real-time.

springboot-kafka-websocket

The goal of this project is to implement two String Boot applications, bitcoin-api and bitcoin-client. The first simulates BTC price changes and, the second, will listen from those changes and update a UI at real-time.

Project Diagram

Applications

• bitcoin-api

  Spring Boot Web Java application service that simulates BTC price changes and pushes those changes to Kafka

• bitcoin-client

  Spring Boot Web Java application that was implemented using Thymeleaf as HTML template. It reads from Kafka and updates its UI using Websocket. It has also a chat where users can talk to each other, by sending comments publicly or privately.

Prerequisites

• Java 11+

• Docker

• Docker-Compose

Start Environment

• Open a terminal and inside springboot-kafka-websocket root folder run

  docker-compose up -d

• Wait for Docker containers to be up and running. To check it, run

  docker-compose ps

Running applications with Maven

Inside springboot-kafka-websocket root folder, run the following Maven commands in different terminals

• bitcoin-api

  ./mvnw clean spring-boot:run --projects bitcoin-api -Dspring-boot.run.jvmArguments="-Dserver.port=9081"

• bitcoin-client

  ./mvnw clean spring-boot:run --projects bitcoin-client -Dspring-boot.run.jvmArguments="-Dserver.port=9082"

Running Applications as Docker containers

Build Application’s Docker Image

• In a terminal, make sure you are in springboot-kafka-websocket root folder

• In order to build the application docker images, run the following script

  ./docker-build.sh

Application’s Environment Variables

• bitcoin-api

  Environment Variable	Description
  MYSQL_HOST	Specify host of the MySQL database to use (default localhost)
  MYSQL_PORT	Specify port of the MySQL database to use (default 3306)
  KAFKA_HOST	Specify host of the Kafka message broker to use (default localhost)
  KAFKA_PORT	Specify port of the Kafka message broker to use (default 29092)
  ZIPKIN_HOST	Specify host of the Zipkin distributed tracing system to use (default localhost)
  ZIPKIN_PORT	Specify port of the Zipkin distributed tracing system to use (default 9411)

• bitcoin-client

  Environment Variable	Description
  KAFKA_HOST	Specify host of the Kafka message broker to use (default localhost)
  KAFKA_PORT	Specify port of the Kafka message broker to use (default 29092)
  ZIPKIN_HOST	Specify host of the Zipkin distributed tracing system to use (default localhost)
  ZIPKIN_PORT	Specify port of the Zipkin distributed tracing system to use (default 9411)

Run Application’s Docker container

• In a terminal, make sure you are inside springboot-kafka-websocket root folder

• Run following script

  ./start-apps.sh

• Wait for application’s Docker containers to be up and running. To check it, run

  docker ps -f name=bitcoin-api -f name=bitcoin-client

Applications URLs

Application	URL	Credentials (user/pass)
bitcoin-api	http://localhost:9081/swagger-ui.html
bitcoin-client	http://localhost:9082	user1/123 or user2/123

The gif below shows two users checking real-time the BTC price changes. Besides, they are using a chat channel to communicate with each other.

Useful Links & Commands

• Zipkin

  Zipkin can be accessed at http://localhost:9411

• Kafka Topics UI

  Kafka Topics UI can be accessed at http://localhost:8085

• Kafka Manager

  Kafka Manager can be accessed at http://localhost:9000

  Configuration

  • First, you must create a new cluster. Click on Cluster (dropdown button on the header) and then on Add Cluster

  • Type the name of your cluster in Cluster Name field, for example: MyCluster

  • Type zookeeper:2181 in Cluster Zookeeper Hosts field

  • Enable checkbox Poll consumer information (Not recommended for large # of consumers if ZK is used for offsets tracking on older Kafka versions)

  • Click on Save button at the bottom of the page.

• MySQL

  docker exec -it mysql mysql -uroot -psecret --database=bitcoindb
  select * from prices;

Shutdown

• To stop applications

  • If they were started with Maven, go to the terminals where they are running and press Ctrl+C

  • If they were started as Docker containers, go to a terminal and, inside springboot-kafka-websocket root folder, run the script below

    ./stop-apps.sh

• To stop and remove docker-compose containers, network and volumes, go to a terminal and, inside springboot-kafka-websocket root folder, run the following command

  docker-compose down -v

Cleanup

To remove the Docker images created by this project, go to a terminal and, inside springboot-kafka-websocket root folder, run the script below

./remove-docker-images.sh