jchain – Blockchain Private Network

A prototype private blockchain system built with Java 21 and Spring Boot. This project was created as an experimental environment to explore blockchain technology and its potential applications in business contexts.

🚀 Current Features

1. Employee Registration

• Create Employees: Register new employees with attributes such as name, email, department, position, and joining date.
• Unique Key: Each employee receives a unique key generated using a cryptographic hash based on their ID and creation timestamp.

2. Attendance Tracking

• Check-in API: Employees can record their check-ins using a REST API.
• Key Validation: The employee key is validated to ensure authenticity.
• Timestamped Records: Each entry includes date and time of attendance.

3. Blockchain Visualization

• Block View: API endpoints to visualize all blocks in the blockchain.
• Attendance History: List all check-ins by employee key.

🧱 Data Persistence

The blockchain data is temporarily persisted in encrypted JSON files to prevent data loss. This approach is planned to evolve into a more decentralized and distributed system in future iterations.

🔮 Upcoming Features

• Supply Chain Management – Product tracking throughout the entire supply chain.
• Document Management – Secure storage and validation of documents.
• Voting Systems – Implementation of a transparent and secure digital voting system.
• Smart Contracts – Automation of legal agreements and business rules.
• Identity Management – Secure handling of digital identities.
• Asset Monitoring – Real-time tracking of physical and digital assets.

🛠 Technologies Used

• Java 21
• Spring Boot
• Lombok
• Jackson
• Postman (API testing)

▶️ How to Run

Requirements

• Java 21
• Maven

Steps

git clone https://github.com/sbrunomello/jchain.git
cd jchain
mvn spring-boot:run

📡 Available Endpoints

➕ Create Employee

POST /api/employees
Content-Type: application/json

{
  "name": "John Doe",
  "email": "john.doe@example.com",
  "department": "IT",
  "position": "Developer",
  "joiningDate": "2023-06-01"
}

🕒 Register Attendance

POST /api/attendances
Content-Type: application/json

{
  "employeeKey": "employee-unique-key",
  "attendanceTime": "2024-06-09T08:00:00"
}

📋 List Employee Attendances

GET /api/attendances/{employeeKey}

🔗 View Blockchain

GET /api/blockchain

🤝 Contributing

Contributions are welcome! Feel free to open issues or submit pull requests.

📬 Contact

• Instagram
• LinkedIn

Developed with ❤️ by Mello.