sample-boot-jpa

Preface

This is a DDD sample implementation using Spring Boot / Spring Security / Spring Data JPA. This is not a framework, please use it as a base template when starting a project with Spring Boot.

Concept of Layering

This is a three-layered architecture based on the famous model, but considers the infrastructure layer as a cross-cutting concern.

Layer
UI	Receives use case requests
Application	Use case processing (including external resource access)
Domain	Pure domain logic (does not depend on external resources)
Infrastructure	DI container, ORM, and various libraries

Usually, public handling of the UI layer is performed using Thymeleaf, but this sample assumes the use of different types of clients and only provides APIs in RESTful format.

Spring Boot Usage Policy

Spring Boot is available for various use cases, but this sample follows the following policies:

• Components that require extended definitions are registered with @Bean. Other components are registered with @Component.
  • ApplicationConfig / ApplicationDbConfig / ApplicationSecurityConfig
• Exception handling is defined at endpoints (RestErrorAdvice). The whitelabel function is disabled.
• Specialized in Hibernate as the JPA implementation.
• The authentication method for Spring Security is HttpSession, not basic authentication.
• Easily provides basic utilities that Spring does not support.

Java Coding Policy

• Java 21 or higher
• Concepts and notations added in Java 21 are used actively.
• Use Lombok actively and reduce verbosity.
• Keep names as brief as possible.
• Do not abuse interfaces.
• DTOs that are part of the domain are defined as inner classes.

Resources

Refer to the following for the package and resource structure.

main
  java
    sample
      context                         … Infrastructure Layer
      controller                      … UI Layer
      model                           … Domain Layer
      usecase                         … Application Layer
      util                            … Utilities
      - Application.java              … Bootstrap
  resources
    - application.yml                 … Spring Boot Configuration
    - ehcache.xml                     … Spring Cache Configuration
    - logback-spring.xml              … Logging Configuration
    - messages-validation.properties  … Validation Message Resources
    - messages.properties             … Label Message Resources

Use Case

Consider the following as a sample use case:

• A customer with an account balance requests a withdrawal. (Event T, Delivery T + 3)
• The system closes the withdrawal request. (Allows cancellation of the request until closing)
• The system advances the business day to the next day.
• The system reflects the cash flow on the delivery date to the account balance.

Getting Started

This sample uses Gradle. You can check the operation easily with an IDE and console.

Server Start (VSCode DevContainer)

The following steps are required:

• Check that Docker is installed.
• Check that VSCode with DevContainer Extension is installed.

Prepare this sample with the following steps:

1. Navigate to the cloned sample-boot-jpa directory.
2. Run the command code ..
3. Choose Open Container

Start the server with the following steps:

1. Open VSCode "Run And Debug".
2. Choose Run sample-boot-jpa.
3. If the console shows "Started Application", the server has started on port 8080.
4. Run the command curl http://localhost:8080/actuator/health

Server Start (Console)

Run the application from a Windows/Mac console using Gradle.

The following steps are required:

• Check that JDK 21+ is installed.
• Prepare PostgreSQL and change the JDBC connection destination in application.yml.
  • DDL/DML files are placed under data/db.

Start the server with the following steps:

1. Navigate to the cloned sample-boot-jpa directory.
2. Run the command ./gradlew bootRun --args='--spring.profiles.active=developer'.
3. If the console shows "Started Application", the server has started on port 8080.
4. Run the command curl http://localhost:8080/actuator/health

Check Use Case

After launching the server on port 8080, you can test the RESTful API execution by accessing the following URLs from the console.

Customer Use Case

• curl -X POST -c cookie.txt -d 'loginId=sample&password=sample' http://localhost:8080/api/login
• curl -X POST -b cookie.txt -H "Content-Type: application/json" -d '{"accountId" : "sample" , "currency" : "USD", "absAmount": 1000}' http://localhost:8080/api/asset/cio/withdraw
  • Request a withdrawal.
• curl -b cookie.txt 'http://localhost:8080/api/asset/cio/unprocessedOut'
  • Search for outstanding withdrawal requests.

Internal Use Case

• curl -X POST -c cookie.txt -d 'loginId=ADMINISTRATOR-admin&password=admin' http://localhost:8080/api/login
• curl -b cookie.txt 'http://localhost:8080/api/admin/asset/cio?updFromDay=yyyy-MM-dd&updToDay=yyyy-MM-dd'
  • Search for deposit and withdrawal requests.
  • Please set a real date for upd*Day.

Batch Use Case

• curl -X POST -c cookie.txt -d 'loginId=ADMINISTRATOR-admin&password=admin' http://localhost:8080/api/login
• curl -b cookie.txt -X POST http://localhost:8080/api/system/job/daily/closingCashOut
  • Close withdrawal requests.
• curl -b cookie.txt -X POST http://localhost:8080/api/system/job/daily/forwardDay
  • Advance the business day to the next day.
• curl -b cookie.txt -X POST http://localhost:8080/api/system/job/daily/realizeCashflow
  • Realize cash flow. (Reflected in the balance on the delivery date)

Please execute according to the business day appropriately.
When executing from a job agent, change the port or block the path with a load balancer, etc. This is an example based on the assumption that an administrator executes from the UI.

License

The license for this sample code is the MIT License. Use this as a base implementation when starting a project with Spring Boot.