user78297: I have an Arduino Nano, and a local Java WebSocket server (ws://localhost:8888) run by a .jar file on my computer.
I'm wondering if it's possible to send data (text, numbers etc.) from the Arduino Nano to the WebSocket server via USB cable (USB-A to USB Mini, one that normally powers the Nano).
If so, what do I need to do it?
A quick Google for WebSocket Arduino libraries reveals:
Websockets and Arduino Websocket Fast, but looking at the examples, the former uses Ethernet.h and the latter uses Wifi.h, and I'm unsure if my board is compatible with that without other modules.

user78100: As @Majenko already said the ATmega328 uses a serial connection to communicate. Another chip on the board translates the serial data to USB-Format and the other way around. This enables your computer to interact with the main chip on the Nano (ATmega328).
To solve your problem you might try using something like this simple serial-to-websocket node-server that listenes to data coming in from a serial port and sends it out over WebSocket.

78297: <p>I have an Arduino Nano, and a local Java WebSocket server (ws://localhost:8888) run by a .jar file on my computer.</p>
<p>I'm wondering if it's possible to send data (text, numbers etc.) from the Arduino Nano to the WebSocket server via USB cable (USB-A to USB Mini, one that normally powers the Nano).</p>
<p>If so, what do I need to do it?</p>
<p>A quick Google for WebSocket Arduino libraries reveals:</p>
<p><a href="https://www.arduino.cc/reference/en/libraries/websockets/" rel="nofollow noreferrer">Websockets</a> and <a href="https://www.arduino.cc/reference/en/libraries/arduino-websocket-fast/" rel="nofollow noreferrer">Arduino Websocket Fast</a>, but looking at the examples, the former uses Ethernet.h and the latter uses Wifi.h, and I'm unsure if my board is compatible with that without other modules.</p>
 78100: <p>As @Majenko already said the ATmega328 uses a serial connection to communicate. Another chip on the board translates the serial data to USB-Format and the other way around. This enables your computer to interact with the main chip on the Nano (ATmega328).
To solve your problem you might try using something like <a href="https://github.com/RandomStudio/serial-to-websocket" rel="nofollow noreferrer">this</a> simple serial-to-websocket node-server that listenes to data coming in from a serial port and sends it out over WebSocket.</p>
