esp-idf/examples/protocols/websocket/README.md

Websocket Sample application

(See the README.md file in the upper level 'examples' directory for more information about examples.) This example will shows how to set up and communicate over a websocket.

How to Use Example

Hardware Required

This example can be executed on any ESP32 board, the only required interface is WiFi and connection to internet or a local server.

Configure the project

• Open the project configuration menu (idf.py menuconfig)
• Configure Wi-Fi or Ethernet under "Example Connection Configuration" menu. See "Establishing Wi-Fi or Ethernet Connection" section in examples/protocols/README.md for more details.
• Configure the websocket endpoint URI under "Example Configuration", if "WEBSOCKET_URI_FROM_STDIN" is selected then the example application will connect to the URI it reads from stdin (used for testing)

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

I (482) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (2492) example_connect: Ethernet Link Up
I (4472) tcpip_adapter: eth ip: 192.168.2.137, mask: 255.255.255.0, gw: 192.168.2.2
I (4472) example_connect: Connected to Ethernet
I (4472) example_connect: IPv4 address: 192.168.2.137
I (4472) example_connect: IPv6 address: fe80:0000:0000:0000:bedd:c2ff:fed4:a92b
I (4482) WEBSOCKET: Connecting to ws://echo.websocket.events...
I (5012) WEBSOCKET: WEBSOCKET_EVENT_CONNECTED
I (5492) WEBSOCKET: Sending hello 0000
I (6052) WEBSOCKET: WEBSOCKET_EVENT_DATA
W (6052) WEBSOCKET: Received=hello 0000

I (6492) WEBSOCKET: Sending hello 0001
I (7052) WEBSOCKET: WEBSOCKET_EVENT_DATA
W (7052) WEBSOCKET: Received=hello 0001

I (7492) WEBSOCKET: Sending hello 0002
I (8082) WEBSOCKET: WEBSOCKET_EVENT_DATA
W (8082) WEBSOCKET: Received=hello 0002

I (8492) WEBSOCKET: Sending hello 0003
I (9152) WEBSOCKET: WEBSOCKET_EVENT_DATA
W (9162) WEBSOCKET: Received=hello 0003

Python Flask echo server

By default, the ws://echo.websocket.events endpoint is used. You can setup a Python websocket echo server locally and try the ws://<your-ip>:5000 endpoint. To do this, install Flask-sock Python package

pip install flask-sock

and start a Flask websocket echo server locally by executing the following Python code:

from flask import Flask
from flask_sock import Sock

app = Flask(__name__)
sock = Sock(app)


@sock.route('/')
def echo(ws):
    while True:
        data = ws.receive()
        ws.send(data)


if __name__ == '__main__':
    # To run your Flask + WebSocket server in production you can use Gunicorn:
    # gunicorn -b 0.0.0.0:5000 --workers 4 --threads 100 module:app
    app.run(host="0.0.0.0", debug=True)