Well, the easiest way would probably be to turn on relay response.
<!--#INCLUDE FILE= "simlib.asp"-->
<FORM METHOD=POST ACTION=
"https://secure.authorize.net/gateway/transact.dll">
<% ret = InsertFP (APIloginid, sequence, amount, txnkey) %>
<INPUT TYPE=HIDDEN NAME="x_login" VALUE="the merchant’s API Login ID">
<INPUT TYPE=HIDDEN NAME="x_version" VALUE="3.1">
<INPUT TYPE=HIDDEN NAME="x_method" VALUE="CC">
<INPUT TYPE=HIDDEN NAME="x_show_form" VALUE="PAYMENT_FORM">
<INPUT TYPE=HIDDEN NAME="x_amount" VALUE="9.95">
<INPUT TYPE=HIDDEN NAME="x_relay_response" VALUE="TRUE">
<INPUT TYPE=HIDDEN NAME="x_relay_url" VALUE="Any valid URL">
<INPUT TYPE=SUBMIT VALUE="Click here for the secure payment form">
</FORM>
Note that you have to also go into your control panel and set the relay response URL there to match the one you specify here, otherwise it will be rejected. The relay URL then receives the POST, determines if it's a valid transmission from Authorize.net and if the transaction went through ok, then sends back another URL that Authorize.net forwards the customer to for their receipt. Here is the PHP version so you can get a basic idea of the structure. I've added some notes and cleaned it up slightly.
<?php
require_once 'anet_php_sdk/AuthorizeNet.php'; // The SDK
$redirect_url = "http://YOUR_DOMAIN.com/receipt_page.php"; // Where the user will end up.
$api_login_id = 'YOUR_API_LOGIN_ID';
$md5_setting = ""; // Your MD5 Setting
$response = new AuthorizeNetSIM($api_login_id, $md5_setting);
if ($response->isAuthorizeNet()) { // Can ignore this if not using MD5 setting
if ($response->approved) // Check response code to see if it's 1
{
// Update your database
$redirect_url .= '?response_code=1&transaction_id=' . $response->transaction_id;
}
else
{
$redirect_url .= '?response_code='.$response->response_code . '&response_reason_text=' . $response->response_reason_text;
}
// Send the Javascript back to AuthorizeNet, which will redirect user back to your site.
echo AuthorizeNetDPM::getRelayResponseSnippet($redirect_url);
}
else
{
echo "Error. Check your MD5 Setting.";
}
?>
