Rent_Flow

Rent_Flow is a professional property management and rent tracking system built with Kotlin and Spring Boot. It provides a robust solution for managing buildings, units, tenants, and automated billing workflows.

Successfully handled 100 concurrent users with ~451 requests/sec, achieving a P90 latency of 125ms and P99 latency under 500ms on a self-hosted Dockerized Spring Boot deployment.

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Documentation Suite

For detailed information, please refer to the specific guides in the docs/ folder:

• Architecture & Design: Deep dive into the layered architecture, design patterns, and system components.
• API Reference: Complete list of REST endpoints, request/response examples, and DTO structures.
• Database Schema: Detailed ER diagrams and table definitions for the PostgreSQL backend.
• Business Logic Guide: Detailed explanation of automated charge generation, occupancy rules, and financial status lifecycles.
• Setup & Installation: Step-by-step instructions for setting up the local development environment.

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Tech Stack

Layer	Technology
Backend	Kotlin + Spring Boot
Database	PostgreSQL
ORM	Spring Data JPA / Hibernate
Build Tool	Gradle
Containerization	Docker
Load Testing	k6
Deployment	Ubuntu Server

Core Features

• Automated Billing: Schedule-based charge generation (Rent, Taxes, Utilities).
• Property Hierarchy: Structured management from Buildings down to individual Units.
• Financial Dashboard: Real-time insights into revenue, occupancy, and overdue payments.
• Receipt Management: Integration with AWS S3 for secure payment document storage.
• Kotlin-First: Leveraging Kotlin's expressive syntax and Spring Boot's powerful ecosystem.

Quick Start

1. Clone & Setup:

   git clone https://github.com/your-username/Rent_Flow.git
   cd Rent_Flow

2. Configure Database: Update application.properties with your PostgreSQL credentials.
3. Run:

   ./gradlew bootRun

Docker Deployment

Build JAR

./gradlew build -x test

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Build Docker Image

docker build -t rentflow .

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Run Container

docker run -d \
-p 8080:8080 \
--name rentflow-app \
rentflow

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View Logs

docker logs -f rentflow-app

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Performance Benchmark

RentFlow was benchmarked using k6 against a Dockerized deployment running on Ubuntu Server.

Test Environment

• Ubuntu Server 24.04
• Docker Engine
• PostgreSQL 16
• Lenovo ThinkPad T450s
• Intel i5
• 8GB RAM

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Load Test Configuration

• Tool: k6
• Concurrent Users: 100
• Duration: 30 seconds
• Throughput: ~451 requests/sec

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Benchmark Results

Metric	Result
Average Response Time	49ms
Median Response Time	12ms
P90	125ms
P95	289ms
P99	493ms
Max Response Time	810ms
Failed Requests	0%

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Endpoints Benchmarked

• GET /buildings
• GET /buildings/{id}
• GET /buildings/{id}/units
• GET /tenants/{id}
• GET /charge/tenant/{tenantId}
• GET /charge-templates

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Deployment Architecture

Client
   ↓
Ubuntu Server
   ↓
Docker Container
   ↓
Spring Boot Application
   ↓
PostgreSQL Database

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