I have, but it does not do this
The problem is that you need to request from the correct IP address. The user might not knwo it but the OS does as it got all the required info during the WiFi connect and DHCP "handshake". The trick is to get the remote side to use that knowledge to act upon it since the DHCP "handshake" does not end up in the realm where your application code runs but is handled hidden in the system/WICED stack.
A workaround might be a skript that extracts the standard gateway from the network driver and triggers an HTTP request against that.