Payment by credit card

Another feature that we have initially left out is online payment by members (see Requirements). We will have a look at how to configure this feature in this section.

In our application members will pay through the PayPal credit card payment system. In order to pay through PayPal one has to have a PayPal account. We will assume that our library has opened such an account. Technically, any system that wants to accept payments by credit card made through PayPal has to call the URL of the PayPal site and pass a number of parameters, such as the name of the account, product quantity, price, product code and URL of the page to return to. The rest is then handled by secure PayPal pages where the customer enters her credit card number and finalizes the purchase. If the purchase is successful PayPal returns to the URL you specified as “success” URL. If the purchase failed PayPal also returns to the URL you specified as “failure” URL.

AwareIM makes it possible to easily integrate credit card payment into your application. We will show you how to do this in the next sections.

First of all we need to configure a business object that will represent the PayPal credit card payment system. To do this we define a new business object as usual (see Configuration of Business Objects), enter its name PayPal and enter one attribute Name¹⁾. Our application will be communicating with the PayPal system, therefore we click on the “Communication” property and AwareIM displays a number of possible channels that it can communicate with.

The channel that we will be communicating through is called the URL channel – see also the Defining Communication Channels section. This channel allows communicating with a software system through URL. We tick the checkbox in the row representing the URL channel we specify the settings of the channel. We enter “https://www.paypal.com/cgi-bin/webscr” as the URL of the service provider – this is the URL of the PayPal page handling the payment. Then we enter “return” as the name of the parameter indicating the URL to return to if a service has been successful. This is the name of the parameter that PayPal expects (among other parameters passed to the PayPal page), which contains the URL that PayPal will return to if payment has been successful. We do not have to worry about the URL itself – this is taken care of automatically by AwareIM. Similarly we enter the name of the parameter indicating the URL to return to if service fails – cancel_return. We click on the OK button and then we click on the “Save” button to create the PayPal object.

Now we need to define the object that will represent parameters that PayPal expects when its URL is called. PayPal expects the following parameters:

We define the new business object called PayPalParameters with the attributes that have exactly the same names as the parameters above. All attributes can be of the “Plain Text” type. We specify the following initial values for the attributes:

Once we have defined the PayPalParameters object we need to define the service of the PayPal object. Intelligent objects can expose services that we can request from rules. We will define such a service for the PayPal object. We open the PayPal object for editing and click on the “Communication” property in the list of properties of the object. Then we click on the “Add” button to add a new service. The “Service” dialog is displayed. We enter the name of the service PayByCreditCard and select the PayPalParameters object as input for this service. Then we click on the OK button and then save changes to the PayPal object.

When a member will be making payment by credit card our application will be creating an instance of the Payment object, just like it does when the operator registers payment of a member . Unlike the registration of payment operation, though, there will be a potentially long period when a member makes a payment through PayPal pages. During this period the Payment object will be in an intermediary state, since we don’t know yet whether the payment will succeed or fail. Therefore we introduce a life cycle for the Payment object – we add the Status attribute to this object with possible values New and Applied. The Applied state is assigned to the object after payment has been completed

We can also have the Failed state which indicates that the payment has failed</callout>

We modify the Payment amount validation rule to consider the New state:

IF Payment.Status='New' AND Payment.Amount > Payment.Member.OutstandingCharges THEN 
   REPORT ERROR 'Payment amount cannot exceed outstanding charges.' 

Once payment has been made we do not want anyone to change its details, therefore we enter the Payment protection rule:

IF  Payment.Status='Applied' THEN 
   PROTECT Payment FROM ALL EXCEPT System 

We also add the action that sets the Payment state to Applied in the “RegisterPayment” process.

In our credit card payment operation we will be creating the instance of Payment object and then use the details of this object to call service of the PayPal object. So we need a process to perform these actions. We define the new MakePayment process that does not require any input²⁾ and has the following actions:

ENTER NEW Payment WITH Payment.Member=LoggedInMember
 CREATE PayPalParameters WITH 
   PayPalParameters.amount=Payment.Amount, 
   PayPalParameters.item_name=Payment.Description
 REQUEST SERVICE PayByCreditCard OF PayPal USING
   PayPalParameters
   Payment.Status = 'Applied'
 DISPLAY MESSAGE 'Your payment has been successfully processed' 

The actions above are quite straightforward. The only point we want to mention here is that we do not create the instance of the PayPal object in the process nor do we need to worry about the PayPal object being in the context. We will create only one instance of the PayPal object and we will do it when the system is initialized, not inside the process. In fact, if we are dealing with an intelligent business object that supports the URL channel only one instance of this object should exist in the system. Consequently, it is not necessary to find this instance to put it in the context – AwareIM will do it automatically.

Now we can define the Pay by credit card menu item in the Member visual perspective. This item will start the MakePayment process. Our members can now pay by credit card online.