j14-finrule

Small API developed in Java 14 with Spring for scheduling financial transfers.

Operations

Transfer Scheduling:
- Calculates fee and feeType based on business rules.
Transfer Cancellation:
- Cancels a transfer, provided it has not already been carried out.
Transfer Query:
- Query transfers by their numeric ID to read data about them.
Transfer List:
- Lists all past and future transfers.

How to Use

There is an OpenAPI 3.0 file in this repository that may be read by documentation generation tools. It's the openapi.yaml file at the root of this repository.

There is also a Postman collection in the repository root: postman_collection.json.

Languages, Frameworks and Tools

Java 14
- A requirement of the application: "Use the latest Java version".
Spring Boot
- The go-to framework for implementing modern REST micro-services in Java.
H2 Database
- A database with in-memory capabilities, to satisfy the requirement "Data persistence in memory only" while still being able to use JPA.
Docker
- For easy setup of the application without the need to install a Java 14 JDK yourself.
Docker Compose
- Used to configure some parameters of the application's Docker image without long command lines.
JUnit 4
- The go-to test framework for unit tests in Java, with Spring integration available.
Logback
- Default logging framework for Spring, also widely used for other kinds of Java applications.
Lombok
- To avoid writing boilerplate code (like getters and setters, toString, equals) in application models.

How to Add New Rules

Simply create a class that implements the FinancialFeeRule interface, annotate it with @Service and define its precedence in the rule chain by using @Order.

Example class header for a class with -1 order, which is processed before any class with an order value than it (because it will be resolved first due to lower order):

@Service
@Order(value = -1)
public class MyCustomRule implements FinancialFeeRule
{
    // ...
}

Runtime Requirements

With Docker

Docker and Docker Compose installed
- Docker Desktop (for Windows users): v2.3.3.2 (46784)
- Docker Engine: v19.03.12
- Docker Compose: 1.26.2

Without Docker

Java 14 runtime installed

Development Requirements

To build the project, you will need at least:

Maven 3.0
JDK 14

Configurations

In the application.properties file located at the root directory of the ZIP archive and inside the resources folder (src/main/resources) of this project, you may alter some parameters, such as the port the API is exposed on.

Deploy Instructions

For Development using Docker

Build:

mvn clean install

Run:

mvn exec exec:docker-up

Stop:

mvn exec exec:docker-stop

Deploying in Production

After the build, a ZIP archive is generated with the artifacts and dependencies of the application in the target folder, following the name template j14-finrule-VERSION.zip.

Extract this ZIP archive in a folder on the target machine.

Deploying with Docker

For deploying in production, run:

docker-compose up --build

In the same working directory where the archive was extracted.

Deploying without Docker

In case the production machine does not have Docker installed, you may also run the application as a simple Java process, executing:

java -Dlogging.config=app/logback-spring.xml -cp "app:app/lib/*" "br.com.henry.finrule.Application"