PyChat: A Simple UDP-Based Chat Application

PyChat is a lightweight chat application designed to facilitate real-time communication between users over a network. Built using the User Datagram Protocol (UDP), PyChat aims to provide a simple yet effective platform for sending and receiving messages. Despite the inherent unreliability of UDP, PyChat implements mechanisms to ensure message delivery and maintain a seamless user experience. The application consists of a server that manages user connections and message exchanges, and a client that allows users to interact with the chat system.

Running the App Locally

To run PyChat locally, follow these steps:

1. Clone the Repository: Clone the project repository to your local machine.

2. Install Dependencies: Ensure you have Python installed on your system. No additional libraries are required as the application uses Python's standard library.

3. Start the Server: Navigate to the directory containing udp_server.py and run the server using the command:

   python3 udp_server.py

4. Start the Client: In a separate terminal, navigate to the directory containing udp_client.py and run the client using the command:

   python3 udp_client.py

5. Interact with the Application: Follow the on-screen instructions to connect, list users, send messages, and retrieve messages.

Features Implemented

• User Connection: Users can connect to the server by providing a username and first name.
• List Online Users: Users can view a list of currently online users.
• Send Messages: Users can send messages to other connected users.
• Retrieve Messages: Users can retrieve messages sent to them by other users.
• Graceful Shutdown: The client can be gracefully shut down using signal handlers.

Security Measures

• Session Management: User sessions are saved locally to ensure continuity between sessions.
• Error Handling: The application includes error handling to manage unexpected situations and provide feedback to users.

Reliability with UDP

Despite using UDP, which does not guarantee message delivery, PyChat implements several mechanisms to enhance reliability:

• Acknowledgment System: Both the client and server use an acknowledgment system to confirm message receipt. If an acknowledgment is not received, the message is resent.
• Retry Mechanism: Messages are sent with a retry mechanism, attempting multiple times before reporting a failure.
• Timeouts: The application uses timeouts to prevent indefinite waiting for responses, allowing it to retry or handle errors appropriately.

By combining these features, PyChat provides a robust and user-friendly chat experience, even over a protocol that does not inherently ensure reliability.