The Checkout Experience
So, PayPal_Returned event is fired after IPN events, is that right ?
Answer : Not strictly but usually. What does it mean ? Ok, as I said, IPN is submitted to your website by PayPal Notification Service. It actually queues the notification task to it's Queue and depending on the tasks the notification service already has, the time when 'IPN event fire' varies. For the PayPal live site, the notification service task queue is not usually long but the task queue for PayPal Sand box is usually very long. So, when testing in Sand box, most of the time, you will find that your subscriber is already back to your website (PayPal_Returned event fired) before IPN events are fired. But, when you are testing in PayPal live site, most of the time you will find that, IPN events are fired before your subscriber is back to your website (PayPal_Returned event fired). Please remember, PayPal_Returned event is Synchronous and IPN events are Asynchronous. One event does not depend on the completion of another event.
Trial Version Alert:
If you already have obtained a License Key and set the License Key from the design mode Smart Tag then you are ready to use the Subscription button from PayPal Website. If you did not set the License Key yet, clicking the Subscription button will take your customer to PayPal Sand Box.
You should take appropriate measures to protect against Fraud Attempts.
Consider the IPN_Subscription / IPN_Payment events as a pure Service Events, do not perform any task that directly interacts with User Interface Controls, Session Variables, Cookies, ViewState etc. When these events are fired, your customer wont see any effect of these events. For example, if you want to set Text of a Label Control 'Thank you for your Payment' in this event, your customer will never see that. Why ? Because, your customer is not directly responsible for firing these events, rather, PayPal Notification Service fires these events in background thread. For that reason, this control Suppresses all HTML that could be rendered to the Event firer (PayPal Notification Service). Also, this control will STOP firing the Page_Load event of the hosting page. WHY ? Maybe you placed some code in your Page_Load event that directly interacts with Session Variables, Cookies etc or time consuming tasks like Executing lengthy SQL queries which is unnecessary or sometimes harmful for IPN session. So, this control will bypass Page_Load event in the IPN Session. But if you want to let this control fire the Page_Load event in the IPN session because you want to set IPN Settings programmatically from the Page_Load event, then, you have that option too. Set "PayPalIPN.EnablePageLoadEventInIPNSession = true" from the property editor and then, Page_Load event will be fired before IPN_Subscription / IPN_Payment events, but you need to be very careful about using Page_Load event in this case.
If you are testing your web site from "Local Host" then IPN_Subscription / IPN_Payment events wont get fired. Because, IPN is activated by a notification service from PayPal, not directly by your customer. So, when the Subscription button submits all the information to PayPal website as a result of 'Click' on the button, PayPal captures the URL of the page where the Subscription button is hosted. When you test from your local host, the URL of the page where the Subscription button is hosted contains 'local host' or '127.0.0.1' and that URL is collected by PayPal so that it can notify as soon as the payment is made. Naturally that URL is not accessible from any other client/website/service other than anyone who is testing from your PC. So, if PayPal submits IPN to your URL with 'local host'/127.0.0.1 your website wont know about it and so this Subscription button will fail to fire IPN_Subscription / IPN_Payment events. The story is not end here. Whenever, PayPal IPN service Fails to get HTTP '200 OK' status from your Website as as result of IPN posting, the service will keep trying to post to the same URL again after few hours and it will keep trying for a certain period until it gets HTTP '200 OK' result from your website. That is bad for PayPal as PayPal's resource is being wasted. So, PayPal can disable the IPN for your account which is bad for you. In order to avoid that problem, this control will detect if the test website is from 'local host' or not. If it is from local host, then, it will NOT pass any IPN information to PayPal so that, PayPal wont submit IPN to your website. By the way, if you do not handle IPN_Subscription / IPN_Payment events and specify a Custom IPN URL then the logic is little different. In that case, the control will check if the Custom IPN URL is a relative URL or not. If it is a relative URL and if you are testing from local host, that means, the final URL would be an URL with 'local host'. So, in that case, the control will not generate any IPN information so that PayPal wont submit IPN. But if your Custom IPN URL is an absolute URL which does not contain 'local host' or '127.0.0.1' then, the Subscription button will pass IPN information to PayPal so that PayPal can submit IPN. In any case, if the control does not pass any IPN information to PayPal, then, PayPal will check if you have specified any default IPN URL in your PayPal profile. If so, then, PayPal will submit IPN to that default URL in these cases. But whenever you upload your test website to a production server where the hosting page of Subscription button has a REAL accessible URL, then, IPN_Subscription / IPN_Payment events will be fired as usual.
Membership users, please note:
If you are using ASP.NET Membership feature in your website, then, you need to allow PayPal to see your page where you placed your IPN_Subscription / IPN_Payment event handler code. That means, if you are handling IPN_Subscription / IPN_Payment events right from your Subscription button, then, the page that hosts your Subscription button should be visible to all. If you are Handling IPN from a dedicated page then, your IPN handler page should be accessible to all users. Assume that you hosted your Subscription button at "Purchase.aspx" page where "Purchase.aspx" page is located in a private folder (Not visible to everyone). Then, you need to add the following section to you web.config file which is located in that private folder.
If you placed your 'Purchase.aspx' page in a public folder then you do not need to worry about setting the above config unless you explicitly blocked the 'purchase.aspx' page from public.
If you do not permit PayPal to post IPN to your page, then, you will find that IPN_Subscription / IPN_Payment events are not being fired.By this time, I hope you already realized that, IPN is a different SESSION created by PayPal for your website and this SESSION is not the same SESSION created by your customer at your website. Since any asp.net designer wanting to set up a site where users pay a membership fee to join, would very likely want to put a user in a Role on IPN_Subscription / IPN_Payment event handler methods. It will be a common mistake if you assume that the Customer is logged in as a member in the IPN SESSION. So, how would you pass the user-name of the Customer to the IPN_Subscription / IPN_Payment events so that you can write code to add your customer in a paid member role by the customer's user name ? Yes, we have designed a very special property named "Additional Data Items". This is a Dictionary type property which can be populated either in design time or programmatically. So, you can pass your customer's user-name by Additional Data Items to the Payment Button and you can access that data right from IPN_Subscription / IPN_Payment events handler method. Once you retrieve that user name of the customer from Additional Data Item, you can add him/her to your paid member role. In order to learn about Additional Data Items, please visit this page .
If you do not have Full Trust configuration in your ASP.NET Web site, then, when handling IPN_X event, you will always get e.IPN.Status = PayPalIPN.StatusCodes.CommunicationError from the IPN_X event arg. Because, IPN Status value is returned after the component tries to communicate with the PayPal notification service in the background by HttpWebRequest class. HttpWebRequest class needs Full Trust configuration.
In order to use PDT, you must have Full Trust configuration in your ASP.NET website, otherwise you will always get e.PDT.Status = PayPalPDT.StatusCodes.Communication_Error from PayPal_Returned event. Because, prior to firing PayPal_Returned event, the control communicates with PayPal website in the background to verify the transaction using a method from WebClient class. Web Client class methods require Full Trust configuration.
If you do not have full trust configuration, you cannot use the PDT feature even manually coding by yourself or using any other technique at all.
Subscription Button Control for ASP.NET Web Form
This page explains the usage and facts about the Subscription button Web Form Server Control. If you intend to use Subscription button within your ASP.NET MVC project, please visit this page.
PayPal Subscriptions and Recurring Payments let you accept recurring payments for your service. Our Subscription Button Control is designed to facilitate you to use that PayPal offered service within your ASP.NET Web site in the most organized Object Oriented way.
When you set up Subscriptions, you can offer subscribers a trial period, special introductory rates, and a regular rate. Subscribers are billed automatically according to the terms you specify, removing the hassle of keeping track of which payments you have and have not received. PayPal Subscription buttons can also help you improve your buyer experience with customizable buttons, secure payments, and the ability to pre populate your subscribers’ PayPal sign up pages. PayPal provides Instant Payment Notifications to give you instant notification of all subscriptions activities and to facilitate Subscription Password Management.
If you are evaluating a Trial Version of this control OR if you want to test with Demo Money, please prepare your Sand Box account before proceeding to this chapter .
In order to keep this page short and simple, the examples are given only in C# language. If you are a VB.NET programmer, please accept our apology. The example snippets are so short and comprehensive that as a programmer you wont have any problem to comprehend. Although the class library reference has examples and snippets in both C# and VB.NET.
You may want to set the properties of your Subscription Button after the customer has clicked the Button. This control has an event named "Click". It is similar to any standard ASP.NET button control's Click Event as shown in the following figure:
If you attach an event handler to this event, then the event handler method will be executed before the data is transferred to PayPal.
Handling Instant Payment Notification (IPN) from PayPal:
When your customer Clicks the final 'Agree' button in the PayPal website, PayPal sends notification to your website asynchronously which is called Instant Payment Notification (IPN).
Not only when the Agree button is clicked, PayPal submits IPN when:
This control can capture that notification and fire a server side event named IPN_Subscription. This control not only just fires the event, but also collects all the transaction data from IPN and offers you a rich set of strongly typed relational object model as event argument object which is not only loved by all Object Oriented Programmers, but also revealing all the headaches from the developer about verification and other complex tasks in IPN Session.
Handle the IPN_Payment event so that you can get notified whenever Payment is made for a Subscription.
Whenever your customer is transferred back to your website from PayPal website after completing or canceling the subscription, you can do additional tasks on your website by handling an event named PayPal_Returned. This control not only just fires the event, but also collects all the transaction data from PayPal if you have turned 'Payment Data Transfer' option ON from your PayPal profile. The event argument object of PayPal_Returned event offers you a rich set of strongly typed relational object model same like the event argument object of IPN_Subscription / IPN_Payment events. This event will take care of notification validation so you just do not need to worry about any dirty code work, rather use the clean data returned by this event argument object.
Once you handled PayPal_Returned event of your Subscription button, your buyer will be taken back to your website after the subscription is started or canceled to sign up. You can check from your Event handler if the subscription was proceeded or canceled as shown below:
Last updated on 4 July 2012, Wednesday, 11:55:33 PM