esp_websocket_client.rst

ESP WebSocket Client

Overview

The ESP WebSocket client is an implementation of WebSocket protocol client for ESP32

Features

• supports WebSocket over TCP, SSL with mbedtls
• Easy to setup with URI
• Multiple instances (Multiple clients in one application)

Configuration

URI

• Supports ws, wss schemes
• WebSocket samples:
  • ws://websocket.org: WebSocket over TCP, default port 80
  • wss://websocket.org: WebSocket over SSL, default port 443
• Minimal configurations:

const esp_websocket_client_config_t ws_cfg = {
    .uri = "ws://websocket.org",
};

• If there are any options related to the URI in esp_websocket_client_config_t, the option defined by the URI will be overridden. Sample:

const esp_websocket_client_config_t ws_cfg = {
    .uri = "ws://websocket.org:123",
    .port = 4567,
};
//WebSocket client will connect to websocket.org using port 4567

SSL

• Get certificate from server, example: websocket.org openssl s_client -showcerts -connect websocket.org:443 </dev/null 2>/dev/null|openssl x509 -outform PEM >websocket_org.pem
• Configuration:

const esp_websocket_client_config_t ws_cfg = {
    .uri = "wss://websocket.org",
    .cert_pem = (const char *)websocket_org_pem_start,
};

For more options on esp_websocket_client_config_t, please refer to API reference below

Application Example

Simple WebSocket example that uses esp_websocket_client to establish a websocket connection and send/receive data with the websocket.org Server: protocols/websocket.

API Reference