Tokenized Invoice Lending Platform

A full-stack, microservices-based platform that enables tokenization of invoices for decentralized lending using Web3 and blockchain integration.

Overview

This project demonstrates a modular architecture where each service is independently deployed and communicates via REST and RabbitMQ. Blockchain integration is done using Web3j to mint tokens representing funded invoices on-chain.

Project Structure

tokenized_invoice_lending_platform/
├── kyc_service/             # Manages SME and LP user KYC
├── invoice_service/         # Handles invoice creation and validation
├── wallet_service/          # Generates and manages blockchain wallet addresses
├── funding_service/         # LP funds invoices, token minted, on-chain receipt stored

Tech Stack

• Java 17,
• Spring Boot 3
• PostgreSQL (used in all services — no H2)
• RabbitMQ (for asynchronous messaging)
• Web3j (Blockchain Integration - smart contract interaction)
• Ganache CLI (local Ethereum simulation)
• Docker & Docker Compose (multi-service orchestration)
• Swagger/OpenAPI (REST API testing)

Features

• SME onboarding with wallet generation
• Invoice creation & validation
• Tokenization and funding of invoice
• Blockchain-based minting of invoice tokens
• Retry mechanism on mint failure
• Token balance retrieval from chain

Inter-service Communication

• REST: For synchronous calls like fetching user/wallet/invoice info
• RabbitMQ: For async funding completion notification

Running Locally

1. Clone the repo

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

2. Start/Stop PostgreSQL, RabbitMQ & Ganache

   docker-compose -f docker-compose.yml up -d
   docker-compose down

• PostgreSQL: localhost:5432 (user: postgres, pass: postgres)
• RabbitMQ UI: http://localhost:15672 (guest/guest)
• Ganache (Ethereum): http://localhost:8545

3. Build & Run Services

Each service is a Spring Boot app. You can start them via:

   cd funding_service
   ./mvnw spring-boot:run

Repeat for invoice_service, kyc_service, and wallet_service.

Blockchain Integration

We use Web3j to interact with the smart contract deployed on Ganache.

• Solidity Smart Contracts (InvoiceToken.sol)
• Ganache or Testnet-compatible node
• Web3j for Java ↔ Blockchain communication

Smart Contract Flow

1. Deploy your contract using Remix or Truffle on Ganache.
2. Generate contract wrappers using web3j:

   web3j generate solidity -a InvoiceToken.abi -b InvoiceToken.bin -o src/main/java -p io.github.deepaganesh.contracts

Contract artifacts (.abi and .bin) are placed under: funding_service/src/main/resources/contracts/InvoiceToken.

Swagger Endpoints

Run services and navigate to:

• KYC: http://localhost:8085/swagger-ui/index.html
• Invoice: http://localhost:8086/swagger-ui/index.html
• Wallet: http://localhost:8087/swagger-ui/index.html
• Funding: http://localhost:8088/swagger-ui/index.html