Like every other chapter in this book, let’s take the Tweet Relevance sample code from Appendix A and use the PayPal product at hand, DoDirectPayment in this case, to implement a payment experience. Although an integration with DoDirectPayment as part of a Website Payments Pro integration normally requires additional integration with Express Checkout according to PayPal’s terms of service, we’ll focus solely on integrating DoDirectPayment in this chapter to maintain maximal focus. (Recall that Express Checkout is discussed at length in Chapters 2 and 3.) A recommended exercise for the seriously interested reader, as presented in the final section of this chapter, is to integrate Express Checkout into this chapter’s sample project.