The goal of this project is to learn Spring Integration. For it, we will implement some Spring Boot applications and try to use the well-known Enterprise Integration Patterns.

On ivangfr.github.io, I have compiled my Proof-of-Concepts (PoCs) and articles. You can easily search for the technology you are interested in using the filter. Who knows, perhaps I have already implemented a PoC or written an article about what you are looking for.

project-diagram

• calculator-api

  Spring Boot Java Web application that exposes an endpoint so that users can submit the operation (addition, subtraction, division or multiplication) they want to perform over two decimal numbers a and b.

  POST /api/calculate -d { "a": number, "b": number, "operation": ["ADD" | "SUBTRACT" | "DIVIDE" | "MULTIPLY"] }
  

• file-service

  Spring Boot Java Web application that exposes an endpoint so that users can get information about a file. This service keeps looking at shared/files folder for created or modified files and save their content and info in MongoDB.

  GET api/files/{filename}
  

• spring-integration-shell

  Spring Boot Shell Java application that has a couple of commands. One is to write some content to a file. Those files are stored in shared/files folder. Besides, there are some commands that uses calculator-api to compute the basic Math operations. There is also has a command that calls file-service in order to get information about a file. All the communication with calculator-api and file-service is over HTTP. Finally, there is a simple command called greet, so that you can display a greeting message on the screen depending on the time of the day.

• Java 21 or higher;
• A containerization tool (e.g., Docker, Podman, etc.)

• Open a terminal and navigate to the spring-integration-examples root folder.
• Run the following command:

  docker compose up -d

• calculator-api

  In a terminal and inside the spring-integration-examples root folder run:

  ./mvnw clean spring-boot:run --projects calculator-api

• file-service

  Open a new terminal and inside the spring-integration-examples root folder run:

  SHARED_FILES_PATH=${PWD}/shared/files ./mvnw clean spring-boot:run --projects file-service

• spring-integration-shell

  Open a new terminal and inside the spring-integration-examples root folder run:

  SHARED_FILES_PATH=${PWD}/shared/files ./mvnw clean spring-boot:run --projects spring-integration-shell

• Build Docker Images

  • In a terminal, make sure you are in the spring-integration-examples root folder.
  • Run the following script to build the Docker images:

    ./build-docker-images.sh

• Environment Variables

  • calculator-api

    None

  • file-service

    Environment Variable	Description
    MONGODB_HOST	Specify host of the MongoDB database to use (default localhost)
    MONGODB_PORT	Specify port of the MongoDB database to use (default 27017)

  • spring-integration-shell

    Environment Variable	Description
    CALCULATOR_API_HOST	Specify host of the calculator-api to use (default localhost)
    CALCULATOR_API_PORT	Specify port of the calculator-api to use (default 9080)
    FILE_SERVICE_HOST	Specify host of the file-service to use (default localhost)
    FILE_SERVICE_PORT	Specify port of the file-service to use (default 9081)

• Start Docker Containers

  • In a terminal, make sure you are inside the spring-integration-examples root folder.
  • Run following command:

    ./start-services.sh && ./start-shell.sh

• calculator-api

  A sample of request to add two numbers:

  curl -i -X POST http://localhost:9080/api/calculate \
   -H 'Content-Type: application/json' \
   -d '{"operation": "ADD", "a": 10, "b": 12}'

• spring-integration-shell

  The spring-integration-shell UI and a sample of execution:

  spring-integration-shell

• file-service

  A sample of request to get information about a file:

  curl -i http://localhost:9081/api/files/file.txt

• MongoDB

  Find all files:

  docker exec -it mongodb mongosh filesdb
  db.myFiles.find()

  Type exit to get out of MongoDB shell

• To stop spring-integration-shell, go to the terminal where it is running and type exit.
• To stop calculator-api and file-service:
  • If you start them with Maven, go to the terminals were they are running and press Ctrl+C.
  • If you start them as Docker containers, go to a terminal and, inside the spring-integration-examples root folder, run the following script:

    ./stop-services.sh

• To stop and remove MongoDB and docker compose network, go to a terminal and, inside the spring-integration-examples root folder, run the command below:

  docker compose down -v

To remove the Docker images created by this project, go to a terminal and, inside the spring-integration-examples root folder, run the following script:

./remove-docker-images.sh