The user authentication credentials are automatically converted to the Base64 encoded string and passed to the server with Authorization: Basic bG9naW46cGFzc3dvcmQ= request header. There is an easy method to wrap your data and send it to server as if you were sending an HTML form using POST . Found inside – Page 479... transaction as JavaScript literals. 5. If the cardholder cancels the transaction, a script in the confirmation page sends a POST request to the callback ... But as it’s forbidden to access the content of an