Basic WebSocket Server

This app demonstrates a WebSocket server running on the device.

SDK directory: applications/gecko_os/basic/websocket_server

API Features Demonstrated

Platforms

This app works on:

WGM160P

Requirements and Prerequisites

Requires a Gecko OS evaluation board, such as a WGM160P_eval.

Other Gecko OS hardware can also be used by changing the source of the logged data to suit your device.

Resources

The initialization file settings.ini is packaged into the App file downloaded to the device.

The file websocket_server_demo.html is downloaded to the device.

Description

This app demonstrates a WebSocket server running on the device.

The device also runs an HTTP Server that serves out a web page to a client system.

On the client system, entering a message in the demonstration web page Message text box sends the message to the server, which then echoes the result back to the client. The web page displays the echoed message in the Message Log text area.

Instructions for Use

Open a Gecko OS serial terminal to the device. See Getting Started, Opening a Gecko OS Terminal.

This app assumes your Gecko OS device is set up with the credentials to join your local network. If you have not already set up network credentials, on the Gecko OS terminal, run the commands:

network_up -s
save

See the Wi-Fi Command API documentation for network_up and save.

After compiling, downloading and running the app, wait until the device is connected to the local network.

Then in a web browser on a computer or mobile device connected to the same network, open the URL http://websocket_server.local/.

On the WebSocket Demonstration page, in the Device IP or Name text box, specify the name websocket_server and click Open WebSocket

When the Session Log text area displays WebSocket open..., type a message in the Message text box and press Enter.

In the Message Log text area, the messages you send from the WebSocket client are shown in orange. Messages echoed from the WebSocket server are shown in blue.

Implementation

gos_app_init

gos_load_app_settings("settings.ini") loads settings.ini. The settings start up the HTTP server when the network comes up, set websocket_server_demo.html as the root web page, and set up the mDNS name websocket_server.
gos_network_restart brings the network WLAN interface down and up again so that the HTTP server amd mDNS service start.
gos_websocket_register_server_event_handlers sets up the event handlers:
- connect WebSocket: websocket_connect_handler
- disconnect WebSocket: websocket_disconnect_handler
- data available from client: websocket_receive_handler
gos_network_register_event_handler sets up wlan_network_event_handler to handle network connect/disconnect events.

wlan_network_event_handler

This logs a message to the Gecko OS terminal when the network goes down or comes up.

websocket_connect_handler

when a client connects, gos_websocket_get_client_info gets the client IP and port information, and logs a message to the Gecko OS terminal.

websocket_disconnect_handler

This logs a message when a client disconnects.

websocket_receive_handler

gos_websocket_read reads data from a WebSocket stream when available.
The data is logged to the Gecko OS terminal
gos_websocket_write echoes data back to the WebSocket stream.

Source

See: