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Sensor Data WebSocket Server

This project implements a WebSocket server for handling real-time sensor data. It listens for incoming connections, receives sensor data in JSON format, and broadcasts it to all connected clients.

Features

  • WebSocket Support: Clients can connect to the server using WebSockets.
  • Real-Time Data Broadcasting: Sensor data received from one client is broadcast to all connected clients.
  • Local IP Detection: Displays the local IP addresses for easy connection.
  • Error Handling: Handles invalid JSON messages gracefully.

Prerequisites

Ensure the following software is installed on your system:

  1. Node.js (v14 or higher)
    You can download Node.js from https://nodejs.org/.

  2. WebSocket Client (optional for testing)
    You can use tools like websocat, browser-based WebSocket clients, or custom scripts to connect to the server.

Installation

  1. Clone this repository:

    git clone <repository_url>
cd <repository_folder>

  2. Install the required dependencies:

    npm install

Usage

Start the Server

Run the server with the following command:

node server.js

Server Output

When the server starts, it will display the local IP addresses and the listening port:

Server running at:
- http://<local_IP_1>:8080
- http://<local_IP_2>:8080

Replace <local_IP_1> and <local_IP_2> with the actual local IP addresses displayed in the output.

Connecting a Client

Clients can connect to the WebSocket server using the following URL:

ws://<server_IP>:8080

Sending Sensor Data

Clients can send JSON-formatted sensor data to the server. Example message format:

{
	"temperature": 22.5,
	"humidity": 65
}

The server will broadcast this data to all connected clients.

Code Overview

Key Functions

  1. getLocalIP()
    Retrieves the local IPv4 addresses of the machine running the server.

  2. HTTP Server
    Serves a basic text response when accessed via a web browser or HTTP client:

    Sensor Data WebSocket Server

  3. WebSocket Server

    • Listens for incoming WebSocket connections.
    • Processes incoming messages:
      • Parses and logs sensor data.
      • Broadcasts data to all connected clients.
    • Handles errors for invalid JSON messages.

  4. Error Logging
    Logs the raw message and error details if a message fails to parse.

Development

Dependencies

  • WebSocket: Provides WebSocket server functionality.
    Install with: 
    npm install ws
  • HTTP: Built-in Node.js module for handling HTTP requests.
  • OS: Built-in Node.js module for accessing network interfaces.

Extending Functionality

To extend the server, you can:

  • Add custom validation for sensor data.
  • Implement authentication for secure client connections.
  • Log data to a database or file system.

Troubleshooting

  1. Port Already in Use
    If port 8080 is occupied, modify the server.listen call in server.js to use a different port:

    server.listen(9090, () => {
    ...
});

  2. Invalid JSON Messages
    If a client sends malformed JSON, the server logs the raw message and an error:

    Error processing message: SyntaxError: Unexpected token ...
Raw message that failed: <message>

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contributions

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

Contact

For questions or support, please contact steve@saphirelabs.com.