Well... the primary required fields for the initial DPM form are as follows:
x_login (your API login ID)
x_fp_timestamp (GMT timestamp)
x_fp_sequence (record number, invoice number, or just a random number)
x_amount
x_fp_hash (see below)
x_relay_response (set to TRUE)
x_relay_url (the URL of your relay response page - must include http:// or https://)
The fingerprint hash is calculated as follows:
if (function_exists('hash_hmac'))
return hash_hmac("md5", $api_login_id . "^" . $fp_sequence . "^" . $fp_timestamp . "^" . $amount . "^", $transaction_key);
// Otherwise...
return bin2hex(mhash(MHASH_MD5, $api_login_id . "^" . $fp_sequence . "^" . $fp_timestamp . "^" . $amount . "^", $transaction_key));You can look up what those functions do in PHP and then find the equivalent for your language.
The relay response page will then receive a set of post fields back from Authorize.net, check for success or failure, and send back an appropriate piece of Javascript for forwarding the customer to your receipt or error pages.
Here's what is usually passed back:
<html>
<head>
<script language="javascript">
<!--
window.location="URL TO SEND TO";
//-->
</script>
</head>
<body>
<noscript><meta http-equiv="refresh" content="1;url=URL TO SEND TO"></noscript>
</body>
</html>
Where the redirect URL usually has GET arguments for response code, transaction ID, and in the case of errors, response reason text. The relay response page is also where you'd update your database if the transaction goes through successfully.
