Payment Flow

Overall OOB Payment Flow
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1. When the buyer lands on Shipping-Billing page, Payment section drop down lists the various payment options. All of these payment options are configured in WCS DB as payment business policies for the store.

Tables used-
Policy/Policydesc/Policycmd/Policytype/Policytyc

2. Once buyer fills the credit card details and click next, AjaxRestOrderPrepare & AjaxRestOrderPIAdd Ajax REST calls are made (after successfull server side validation of credit card details using CheckCCNumberCmdImpl) which results in OrderPrepare and PIAddCmdImpl invocation respectively. PIAddComImpl adds the payment instructions to the order i.e. in PPCPAYINST and PPCEXTDATA WCS tables.
    CheckoutPayments.js -> processCheckout -> processPIAndCheckout -> addPaymentInstructions

3. Once buyer submits the order, payment plugin will be invoked and entries are made in ORDPAYINFO, PPCPAYMENT and PPCPAYTRAN tables-
    CheckoutHelper.js -> checkoutOrder -> AjaxRESTOrderSubmit

Typical Punchout Payment Setup Steps

In a typical punchout payment configuration below steps are being followed-
- Configuring the new Payment method in the DB
- Configuring the new Payment method in the payment xml files 
- Create the payment method jsp and place it at intended location. 
- Creating a Payment Plug-in
- Customizing the Billing Page Storefront
- Customizing the CallBackCmd with action registration in struts-confog-ext.xml and ACP load
- Configuring merchant related information
- Configuring certificate for the handshake
- Testing the setup with PSP test account.

These steps are explained in detail below-

Configuring a new Payment/Refund method 
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In order to add a new payment/refund method we would be required to-
a. Make entries in OOB WCS tables (POLICY/POLICYDESC/POLICYCMD with the Payment/ReturnPayment type)
b. Define the payment/refund actions/rules in XML files.

1. Configure Payment
toolkitDir/workspace/WC/xml/config/payments/ppc/plugins/PSP/PluginDeployment.xml
2. Configure Payment Method
PaymentMethodConfigurations.xml
3. Configure Action Rules
toolkitDir/workspace/WC/xml/config/payments/edp/groups/default/PSP/ with all the files copied from toolkitDir/workspace/WC/xml/config/payments/edp/groups/default/CreditCardOffline
4. Add Payment Mappings
toolkitDir/workspace/WC/xml/config/payments/edp/groups/default/PaymentMappings.xml
5. Map payment systems to payment plug-ins
PaymentSystemPluginMapping.xml

For new entry inside POLICY table, Business Policy Name must match the payment/refund method ID configured in payment rules (the paymentMethod value in the PaymentMethodConfigurations.xml file, or the refundMethod value in the RefundMethodConfigurations.xml file).

Merchant Feature
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Merchant information is managed in below WCS tables-
MERCHANT, MERCHCONF, MERCHCONFINFO and STOREMERCH

Creating a Payment Plug-in
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Create an EJB stateless session bean.
Ensure your plug-in remote interface extends the Plugin or QueryablePlugin interface.
Create a plug-in deployment descriptor.
Create a JAR file (EJB module).

Payment Business flow: Extension Points
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In a typical setup which is subject to customization-
On WCS order submission, payment is authorized with order total amount and order is transferred to the external system( subject to customization ). After order fulfilment by the external OMS, a shipment confirmation message is sent back to WCS to capture payment for the shipped order items in this package.

For Payment, PrimePaymentCmd is called at Order Submission ( ProcessOrderCmdImpl )
ReservePaymentCmd is called at ReleaseToFulfillment
FinalizePaymentCmd is called at shipment confirmation

Bypassing Payments : Void Implementations
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Though bypassing the OOB payment flow can be done through bypassing the ajax calls from shipping billing page to bypass the call to PIAddCmd however below OOB void commands can also be used-
e.g. com.ibm.commerce.edp.commands.PrimePaymentCmd                 com.ibm.commerce.edp.commands.PrimePaymentVoidCmdImpl

Payment life cycle
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a. There are three stages to payment processing: validation, reservation, and finalization.

b. The payment life cycle is related to the order life cycle stages: order capture, release to fulfillment, and shipping.

c. Order capture- Payment validated
Release to fulfillment- Payment reserved
Order Shipping- Payment finalized