ATM Emulator

Overview

• Solution has two services and one database module:
  • bank-service provides bank services: Cash deposit, Cash withdrawal, Check balance, etc.
  • atm-service simple client for bank-service.
  • atm-db postgres database docker image.
• To access atm-service two-step authentication is needed, finally atm-service generates limited time access token.
  • /api/authentication/initiate method checks if card is valid and generates access token which is valid only for accessing finalize method.
  • /api/authentication/finalize method validates card preferred authentication method (PIN, fingerprint etc.), and generates access token which is valid for accessing rest of the atm services.
  • After finalizing authentication JWT token payload looks like:

  {
    "sub": "1111222233334444",
    "preferred_auth": "FINGERPRINT",
    "roles": [
      "FINALIZED_AUTHENTICATION"
    ],
    "iat": 1640896897,
    "exp": 1640898097
  }

• To access bank-service some API-KEY needs to be set as a header.
• bank-service automatically creates database schema and loads some sample data. There are about three main tables:
• Hibernate envers is used for auditing.
• resilience4j is used for circuit breaking and rate limiting.
• Both of the services have swagger ui configured and can be accessed at /swagger-ui/index.html
• Logging can be configured by setting LOG_LEVEL env variable.

Start ATM Emulator

• Simplest way to start everything is to use docker-compose which will start postgres database and two services.

docker-compose up

• Otherwise, apps can be started using java. (postgres database is required as well)
• Access atm-service swagger at: http://localhost:8080/swagger-ui/index.html
• Access bank-service swagger at: http://localhost:8090/swagger-ui/index.html
• Postman can be also used to test some endpoints. See ready to use postman collection in source files. ATM Emulator.postman_collection.json