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This is a DDD sample implementation usingSpring Boot.
It is not a framework, but a simple example of implementation based on Evans's DDD.

This approach is straightforward and based on Evans's book, rather than verbose approaches like Clean Architecture or Hexagonal Architecture.

This follows the famous three-layer model, but considers the infrastructure layer as a cross-cutting concern.

Usually, the UI layer handles public interactions using Thymeleaf, but this sample assumes the use of different types of clients and only provides APIs through RESTful endpoints.

Spring Boot can be used in various ways, but this sample follows the following policies:

• Use standard configurations as much as possible, such as DB settings.
• Configuration files use YAML. XML files are not used for Bean definitions.
• Exception handling is defined at endpoints (RestErrorAdvice).

• Java 21 or higher
• Use Lombok actively to reduce boilerplate code.
• Keep names as brief as possible.
• Do not overuse interfaces.
• DTOs that are part of the domain are defined as inner classes.

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    - messages-validation.properties  … Validation Message Resources    - messages.properties             … Label Message Resources

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.

This sample usesGradle. You can check the operation easily with an IDE or console.

The following steps are required:

• Ensure Docker is installed.
• Ensure VSCode with DevContainer Extension is installed.

Prepare this sample with the following steps:

1. Navigate to the clonedddd-java directory.
2. Run the commandcode ..
3. ChooseOpen Container.

Start the server with the following steps:

1. Open VSCode "Run And Debug".
2. ChooseRun ddd-java.
3. If the console shows "Started Application", the server has started on port 8080.
4. Run the commandcurl http://localhost:8080/actuator/health.

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

The following steps are required:

• Ensure JDK 21+ is installed.

Start the server with the following steps:

1. Navigate to the clonedddd-java directory.
2. Run the command./gradlew bootRun --args='--spring.profiles.active=dev'.
3. If the console shows "Started Application", the server has started on port 8080.
4. Run the commandcurl http://localhost:8080/actuator/health.

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

• curl -X POST -H "Content-Type: application/json" -d '{"accountId" : "sample" , "currency" : "JPY", "absAmount": 1000}' http://localhost:8080/asset/cio/withdraw
  • Request a withdrawal.
• curl 'http://localhost:8080/asset/cio/unprocessedOut'
  • Search for outstanding withdrawal requests.

• curl 'http://localhost:8080/admin/asset/cio?updFromDay=yyyy-MM-dd&updToDay=yyyy-MM-dd'
  • Search for deposit and withdrawal requests.
  • Please set actual dates for upd*Day parameters.

• curl -X POST http://localhost:8080/system/job/daily/closingCashOut
  • Close withdrawal requests.
• curl -X POST http://localhost:8080/system/job/daily/processDay
  • Advance the business day to the next day.
• curl -X POST http://localhost:8080/system/job/daily/realizeCashflow
  • Realize cash flow. (Reflects to the balance on the delivery date)

Please execute these according to the business day appropriately.

The license for this sample code isMIT License.Use it as a base implementation when starting a project using Spring Boot.