I realise that I can receive parameters in the query string via the following syntax:
This also seems to work for parameters encoded in a query string format inside the message body of a POST request.
However, my use case involves a public sites page that needs to receive / parse a JSON string in the message body of the post request. This message body content is set in stone, as it's being sent from a server that's outside my control (and outside of SF) - I can only provide the URL to send it to.
Is there any way to obtain this data, or if not any other possible workaround from within SF?