adi_webhook provides a mechanism to easily implement webhooks on Textpattern websites. It waits for incoming connections and, if URL variables (and values) match predefined settings, will execute the code of your choice.
It’s a bit like adi_gps in that it takes notice of URL vars, but unlike adi_gps it provides a mechanism to selectively act on the data received.
See the help supplied with the plugin, or have a look online.
adi_webhook was created in response to a request from Gary (giz) to process MailChimp callbacks.