Welcome to FinCra Wallet! This application allows users to manage their virtual wallets, perform transactions, and check their balances.
- Features
- Prerequisites
- Installation
- Usage
- API Endpoints
- Technical Decisions
- Database Decisions
- Contributing
- License
- User Authentication: Users can log in and log out of their accounts securely.
- Wallet Management: Users can view their wallet balances, credit funds, debit funds, and transfer funds to other users.
- Secure Transactions: Passwords are hashed for security, and transactions are performed within database transactions for data integrity.
- Deadlock Prevention: Deadlocks in database transactions are prevented by implementing a retry mechanism that automatically retries the transaction in case of a deadlock error.
Before you begin, ensure you have met the following requirements:
- Node.js: Make sure you have Node.js installed on your local machine.
- Postman: You'll need Postman (or similar tool) for API testing.
To install the FinCra Wallet application, follow these steps:
-
Clone the repository:
git clone https://github.com/ortupik/fincra-wallet.git
-
Navigate to the project directory:
cd fincra-wallet -
Install dependencies:
npm install
To run the FinCra Wallet application, follow these steps:
-
Compile TypeScript files:
npx tsc
-
Start the application:
node dist/app.js
The application will start running on http://localhost:3000.
The FinCra Wallet application exposes the following API endpoints:
POST /wallet/login: Log in with username and password.POST /wallet/logout: Log out the currently authenticated user.GET /wallet/balance: Get the current balance of the authenticated user.POST /wallet/credit: Credit funds to the authenticated user's wallet.POST /wallet/debit: Debit funds from the authenticated user's wallet.POST /wallet/transfer: Transfer funds from the authenticated user's wallet to another user's wallet.
For detailed information on each endpoint and their request and response formats, refer to the API documentation or Postman collection.
TypeScript was chosen as the primary language for this project due to its strong typing system, which helps catch errors during development and improves code maintainability. Additionally, TypeScript provides better IDE support and code completion, making the development process more efficient.
Express.js was chosen as the web framework for handling HTTP requests and routing. It is lightweight, flexible, and widely used in the Node.js ecosystem. Express.js allows for easy creation of RESTful APIs and middleware integration, making it a suitable choice for building the backend of the FinCra Wallet application.
SQLite was chosen as the database for storing user information and wallet balances. SQLite is a lightweight, file-based database that is easy to set up and does not require a separate server process. It provides sufficient performance for small to medium-sized applications and is well-suited for prototyping and development purposes.
All financial transactions are performed within database transactions to ensure data integrity. This ensures that operations like crediting, debiting, and transferring funds are atomic and consistent, even in the face of concurrent access.
Pessimistic locking is used in transfer scenarios to prevent race conditions. Briefly locking the sender's balance row before reading it guarantees that another transaction hasn't modified it concurrently. This avoids situations where two transfers might succeed despite insufficient funds due to concurrent access.
Deadlocks in database transactions are prevented by implementing a retry mechanism that automatically retries the transaction in case of a deadlock error. This ensures that transactions are eventually executed successfully without causing deadlock-related issues.
Contributions are welcome! Please feel free to submit a pull request or open an issue if you encounter any problems or have suggestions for improvements.
This project is licensed under the MIT License.