feat(websocket): Added linux port for websocket

components/esp_websocket_client/examples/target/README.md

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+# Websocket Sample application
+
+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.
+* 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:
+
+```python
+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)
+```