Vehicle Leasing and Contract File [B2C, B2B]

Main directories with source code (Main project modules):

contractapi: backend API, newer implementation, in Kotlin, cleaner approach
contract: backend API, older implementation in Java, smaller codebase size for reduced carbon footprint
clientng: frontend app, Web UI implementation in Angular 18 / TypeScript

Note: The code here is available in repos for quick review and feedback. Continuous development is going on.

This project is a commerce-targetting app for the following classes of end-users:

lessee, referred to as customer in the project, and
lessor, referred to as provider.

The app is designed with two modules contained in it:

backend, in the directory contractapi, and
frontend, in the directory clientng. (under active development)

Main project directories

clientng: Angular implementation of frontend, just enough to invoke API with a lightweight Web interface
contractapi: Backend API implementation

One more implementation (ReactJS-NextJS) of frontend is also to be presented in future.

Using this app, Lessees can perform these actions in the context of vehicles and leasing contracts:

take vehicles on lease,
abide by and fulfill such leasing contracts, and
return the leased vehicles to respective providers.

User Self-Help Portal: The usage scenarios for lessors are not ready in the current version of the app as the app is more focused towards customer usage.
However, the app may be easily extended to add lessor use cases and administrator scenarios.

Technologies Used to Build the versatile Utility

Angular 18 (Frontend Web UI with Angular 18)
Kotlin 1.9 (Java 21 API level)
Spring Boot 3
MySQL (containerized)
JPA (Jakarta Persistence API)
Hibernate for JPA/ORM
Docker with multi-stage docker-compose and Dockerfile
Gradle (Kotlin DSL)
Flyway for database migration
SLF4J for logging
ELK stack (ELK: Elasticsearch, Kibana, Logstash) for log monitoring and analysis (to be added soon)
React 18 (Frontend app with React 18, TypeScript and Vite/Bun planned for future)

The Spring 2025 has brought good luck with these developments

the stable and charming frontend app with Angular
to use parameters for secrets with Docker Compose and enhance the platform security
to orchestrate the containers in Kubernetes clusters (next up!)

Screenshots

Developer Experience (Containers running smooth and stable)

The following screenshots depict the capabilities of this versatile application:

Contract Manager

Customer Manager

Vehicle Manager

Home View

Vehicle API (invoked directly with Dev Tools)

Customer API (invoked directly with Dev Tools)

Lease Contract API (invoked directly with Dev Tools)

Vehicle API (invoked with Lease Contract Web App)

Customer API (invoked with Lease Contract Web App)

Lease Contract API (invoked with Lease Contract Web App)

Business Scenario and Use Cases

Main Actors

Customer, with properties: name, birthdate
Vehicle, with properties: brand, model, year of manufacture, VIN, price
Lease Contract, with essential properties: lease contract number, monthly rate (for billing)

Viewing Contract Summary [under development]

The following details are shown at summary level:

lease contract number
customer name
vehicle details (branc, model, year)
VIN separately ("--" shown if VIN is not available)
contract rate
vehicle price
anchor link to view more details

Indicative illustration is below:
|----------Contract Overview---------------------------------------------------------------------------------------------|
|Contract Nr. |Customer Name |Vehicle |VIN |Contract Rate (Monthly) |Vehicle Price More Details |
|134856 |Maximill Muster |Audi A20 (2023) |A65413 |654,20 |33465,80 |
|146349 |Angel Angle |Neo X4 (2024) |-- |453,00 |40321,00 |
|------------------------------------------------------------------------------------------------------------------------|

Customer Entry Form

It is a form with fields to enter customer name and birthdate, along with "Update" and "Cancel" buttons.

Vehicle Entry Form

It is a form with fields to enter all five properties (detail points) of vehicle to add or update, with "Update" and "Cancel" buttons.

Lease Contract Entry Form

A form to enter contract number, monthly rate of contract, related customer name and related vehicle details. Customer name and vehicle details may be picked out of database in order to select existing data about customer and vehicle, respectively.

Preconditions to Run the Application

This application requires the following software packages to run properly:

a command line interpreter. Bash is preferred. CMD for Windows also works. The command in this readme run very well with Bash. For having Bash on a Windows box, you may install Git Bash.
Docker
a web browser. Chrome is preferred. Other web browsers may work for most functionalities.

Installation

The application can be set up and started in two distinct methods.

1. Local build and execution

Using your favorite Terminal app for shell, clone the files (source code and configuration) from GitHub repository:

git clone https://github.com/rishiraj88/leasing.git

In your file explorer, go to leasing/contractapi directory:

cd leasing/contractapi

Build the project locally with gradle wrapper:

./gradlew build

2. Pulling the pre-built Docker image

Run this command in Terminal app to pull and start the latest contract image published on Docker Hub for project backend:

docker run i50729/contractapi

In its current stage of development, the backend app runs well with locally available mysql container and the accompanying frontent clientng.

How to Start the Application

Now you may use the application by visiting this URL:

http://localhost:4200/home

Freely navigate to and use the sections Customers, Vehicles and Leasing Contracts.

Reason of Chosen Solution Style and Technologies

The chosen solution corresponds to the use of the modern technologies available so as to model complex dynamic systems easily. Hence it enables the businesses to work on cash-heavy businesses more conveniently.

General Notes

Due to some constraints, I have built the MVP. For enhancing and fostering the solution, tech discussions on relevant parameters and methods are always cited and welcome.

Notes for Developers

The backend of the app has been packaged and published with the following commands:

In your file explorer, go to leasing/contract directory:

cd contractapi

Build the project locally with gradle wrapper:

./gradlew build

Build Docker image with:

docker build -t i50729/contractapi:latest .

Push the Docker image for publishing with:

docker push i50729/contractapi:latest

The Frontend of the app can be started as follows:

download as ZIP the following directory to your workspace:

clientng

Extract and go to clientng directory:

cd clientng

Build and run the Angular-based frontend with thie commands:

npm install

ng serve

Current Status of Functionalities

Only creating and updating customer data is possible. Listing or deleting customer data is not provided for security purpose as the app is to be used by vehicle customers.
Only adding and modifying vehicle data is possible for secure use by customers.
Policy contracts can be listed and viewed by respective customers for the vehicles leased to them.
Experimentation on Containers and Packaging are underway on develop branch.

For Feedback, Queries, Collaboration and More

LinkedIn Messaging: https://linkedin.com/in/rishirajopenminds
Open Contact Card: https://bio.link/rishiraj49de
Microblogging and quick notes on X: https://x.com/RishiRajDevOps
Other Repositories of Shared Interests: https://github.com/rishiraj88?tab=repositories

rishiraj88/leasing