As explained in this webpage, the WebSocket protocol allows full-duplex, bi-directional communications between a server and clients.
You may wish to skip to the relevant section after you have chosen whether you are using WiFi or Ethernet

Sending Hello World from the Mbed: Ethernet

Code

The main code:

#include "mbed.h"
#include "EthernetInterface.h"
#include "Websocket.h"
 
 
int main() {
    char recv[30];
 
    EthernetInterface eth;
    eth.init(); //Use DHCP
    eth.connect();
    printf("IP Address is %s\n\r", eth.getIPAddress());
 
    Websocket ws("ws://sockets.mbed.org:443/ws/demo/wo");
    ws.connect();
 
    while (1) {
        ws.send("WebSocket Hello World over Ethernet");
        wait(1.0);
    }
}

Note that the WebSocket API is the same for using a WiFi module or an Ethernet connection

2. You should be ready!

• You can now download this program into your mbed
• Visit the webpage of your own channel: http://sockets.mbed.org/your_own_channel/viewer

3 - Demo

You can check that all is working by visiting the webpage of your own channel: http://sockets.mbed.org/your_own_channel/viewer
For instance: http://sockets.mbed.org/samux/viewer


Et Voilà! We are able to see on our webpage Hello World over an Ethernet network!

Now, if you want, you can write your own webpage to process and display the data coming in on your channel whichever way you wish!

Conclusion

After this tutorial, you are able to send messages to every webpage connected to a websocket server. You can imagine sending data from sensors and print or display values received in the webpage. Sensors are now accessible all over the world. You can take a look to the Internet Of Things project where data are sent and displayed in real time using another HTML5 feature: canvas.