Combine a database, PayPal subscriptions, and the IPN system to manage subscriber accounts.
If your web site offers something special that people are willing to pay for, such as access to a technical information database or specialized businessto- business commerce site, you might want to offer subscriptions. PayPal makes it easy. Using IPN, your web server, and your online database, you
can easily create an entirely automated system.
Many adult sites on the Internet are available on a subscription basis. Don’t offer subscriptions to these sorts of sites
with PayPal. Your site’s content must be allowed under Pay- Pal’s Acceptable Use Policy; otherwise, you might find that your account has been limited.
For the purposes of this example, let’s say you offer access to a Rhesus monkey marketing database for the low, low price of $30 per month. This opt-in database contains the monkey name, monkey age, aregiver name, and mailing address of over 10,000 monkeys across North America. You offer your subscribers, typically Rhesus monkey supply vendors, access to this information
for marketing purposes.
You’ll need four things to implement your subscription business model:
• A Subscribe button on your web site
• An online database that includes a subscribers table
• An IPN script to keep tabs on new, renewed, and expired subscriptions
• Dynamic pages that check a visitor’s status before allowing access
Creating a Subscribe Button
The Subscribe button for your site can come straight from PayPal’s button generator on the Merchant Tools page (log into PayPal and click the Merchant Tools tab). This example (created without encryption) should look familiar if you have created any unencrypted Buy Now or Donate Now buttons.
The variables a3, p3, and t3 set the amount, period, and time unit of the subscription, respectively:
Setting Up Your Database
Your access control database can be simple. A single table, shown in Table 6-1, containing the email address and the password of your subscriber is all you need. For this example, the table subscribers contains two alphanumeric fields: email and password. You could issue customer usernames to your subscribers, but you might be better served if you follow Pay- Pal’s example and use email addresses to identify users. Passwords can be stored as plain text.
Table 6-1. A database to keep track of your subscribers
ID email password
4005 shannon@paypalhacks.com sR3Du4#m77ca
4006 dave@paypalhacks.com go3@c23-dad43
4007 david@paypalhacks.com fae0v32c&ewf2
Processing Subscriber Notifications
You need to handle two kinds of notifications from PayPal: the addition of new subscribers to your database when they sign up and removal of subscribers whose subscriptions lapse or are cancelled. Here’s a snippet of ASP that does this (see the “Database Coding and Platform Choices” section of
the Preface for database considerations):
<% if Request.Form("txn_type") == "subscr_signup" then ' Add this subscriber to the database ' Use SQL like this: set cInsSubscr = Server.CreateObject("ADODB.Command") cInsSubscr.ActiveConnection = "DRIVER={Microsoft Access Driver (*.mdb)};DBQ="C:/InetPub/wwwroot/database/dbPayPal.mdb") cInsSubscr.CommandText = "INSERT INTO subscriber (email, password) VALUES ( '" & Request.Form("payer_email") & "', 'drowssap')" cInsSubscr.CommandType = 1 cInsSubscr.CommandTimeout = 0 cInsSubscr.Prepared = true cInsSubscr.Execute( ) ' Email the password to the new subscriber elsif Request.form("txn_type") == "subscr_cancel" then ' Remove a subscriber from the database ' Use SQL like this: set cDelSubscr = Server.CreateObject("ADODB.Command") cDelSubscr.ActiveConnection = "DRIVER={Microsoft Access Driver (*.mdb)};DBQ="C:/InetPub/wwwroot/database/dbPayPal.mdb") cDelSubscr.CommandText = "DELETE * FROM subscriber WHERE email = '" & Request.Form("payer_email") & "'" cDelSubscr.CommandType = 1 cDelSubscr.CommandTimeout = 0 cDelSubscr.Prepared = true cDelSubscr.Execute( ) end %>
Don’t really give every one of your subscribers the same password (drowssap in this example). Instead, use an algorithm for generating a password or let them choose a password for themselves in the subscription process. Don’t forget to turn on IPN in your PayPal account and point it at your IPN processing script .
Controlling Access to Your Valued Content
Now you have a list of valid subscribers that is automatically updated by PayPal and your IPN script. Next, you’ll need to make use of this information by ensuring that visitors to your site are on the current subscriber list.
In this example, all the members-only pages are dynamic ASP pages. The first thing the code does is check that the user is properly logged in. If not, the premium content is not displayed and the user is redirected to a Sign In page. You know the user is signed in if the magic cookie has been set.
<% 'content.asp 'Check for the magic cookie. 'If not found, redirect if Response.Cookies("MagicMonkey) != "swordfish" then Response.Print("Please log in before accessing this page.") Response.Redirect("login.asp") end %>
The Sign In page simply asks for the user’s email address and password. If this information shows the visitor is a valid subscriber, a cookie is set on the user’s browser. The cookie contains the magic word that allows your subscribers access. Without this cookie, set to the proper magic word, no one can access subscriber-only content.
<% 'Sign in page: sign_in.asp 'Database connection code goes here 'Connect to database and create recordset connStore = "DRIVER={Microsoft Access Driver (*.mdb)}; DBQ="C:/InetPub/wwwroot/database/dbPayPal.mdb") set rsCookies = Server.CreateObject("ADODB.Recordset") rsCookies.ActiveConnection = connStore rsCookies.Source = "SELECT * from subscribers WHERE email = '" & Request.Form("email") & "' AND password = '" & Request.Form("password") & "'" rsCookies.Open( ) 'IF the query turns up a match, execute this code: 'Set new cookie session in MagicMonkey ' "swordfish" happens to be today's magic cookie word Response.Cookies("MagicMonkey") = "swordfish" 'Set cookie expiration Response.Cookies("MagicMonkey").Expires = Now( ) + 1 'one day Response.Print("Thank you for logging in. Click
here to start selling stuff to a bunch of monkey lovers.")
'ELSE do this:
Response.Redirect("login.asp")
%>
Your page, login.asp, should contain an HTML form that asks for each customer’s email address and password. Its data is posted to sign_in.asp.
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