A Post-back, also known as a “call back” or “silent post”, is a method by which your app can react to events that occur during the Subscription Life cycle (e.g. a new subscription, a recurring payment is declined, a subscription is upgraded, etc.). For example, your blog or iPhone app can use post-backs to grant customers access to special content, and restrict access to others.

A post-back URL is saved in your Merchant Settings. The URL points to a post-back script in your app. We send a post-back message to your post-back script when there is an event (e.g. a sign-up). Your script uses the information in the post-back message to trigger an action (e.g. enable content to a new user).

A full list of events and sample scripts are available.

The Post-back URL, which is set in the Notification Settings area of the Merchant Center (separately for each store), defines the location of script on your Web site or App that contains code designed by you to interpret and react to the information provided by SubscriptionBridge in the post-back message.

Here the steps required to configure your Post-back URL:

1. Log into the Merchant Center.
2. Navigate to “Notification Settings”
3. Under “Advanced Settings” find “Post-back URL”
4. Type your URL into the box. We recommend using a secure URL.
5. Click “Save Notification Settings” at the bottom of the page.

The script located at the Post-back URL can be written in any programming language capable of receiving and parsing XML data. We have sample post-back scripts in our samples section.

• PHP
• ASP

The post-back message is plain old XML so it is compatible with all programming languages. The XML contains the Subscription ID (GUID) and the Event Code (Event_Code).

Here is an example message:

* Sample XML:

<?xml version="1.0" encoding="utf-8"?>
<SB_Callback>
<GUID>Subscription ID</GUID>
<Event_Code>Event Code</Event_Code>
</SB_Callback>

View a list of XML notifications sent by SubscriptionBridge to the Callback URL to see what kind of information SubscriptionBridge will be sending to your script.

You can test a Post-back for a Subscription directly from the Merchant Center. Just navigate to any Subscription's details page. From there click the “More” button, then click “Test Post-backs”. By this method you can test your Post-back script is working properly.