Here is a brief summary of the chapters in the book and what you can expect from each:
Provides a 10,000-foot overview of interacting with PayPal APIs as web services and introduces GAE, the primary development platform that’s used throughout the book.
Showcases Express Checkout, PayPal’s premier checkout solution, and demonstrates how to implement a basic Express Checkout payment flow for Tweet Relevance.
Teaches you how to tailor and improve the Express Checkout flow established in the previous chapter as an Express Checkout for Digital Goods payment flow.
Introduces Adaptive Payments and shows you how to implement an Adaptive Payments checkout flow for Tweet Relevance in which funds are sent to multiple recipients.
Teaches you how to accept credit cards directly from your site using Website Payments Pro’s Direct Payment option as a checkout option for Tweet Relevance.
Demonstrates how to use Instant Payment Notifications (IPNs) to handle custom actions associated with a payment, such as sending a confirmation email to a customer when a purchase is completed.
Introduces Tweet Relevance, the foundational reference application that’s used throughout the book as a baseline project.
Provides a minimal overview of Mobile Payments Libraries (MPLs). This is also where you can go to get started developing solutions for iOS, Android, and BlackBerry.
It is highly recommended that you read Chapters 1 and 2 before diving into any other chapter, because these initial chapters try to be as thorough as possible in establishing a foundation that future chapters build upon.