PayPal APIs: Up and Running, 2nd Edition

Chapter 1. PayPal API Overview

This chapter provides a very brief overview of PayPal’s Name-Value Pair (NVP) APIs, the primary way that you’ll interact with PayPal products throughout the remainder of this book. Since using the NVP APIs is as simple as making some HTTP requests and parsing the responses, we’ll get a Python project up and running with Google App Engine (GAE) as part of this initial overview. Future chapters all use Python-based GAE projects, so unless you’re definitely planning to port the code without running it, you should make the most of this opportunity to learn the basics. After reading this chapter, it is highly recommended that you check out and run the sample code for Tweet Relevance as introduced in Appendix A.

Overview of PayPal API Requests

PayPal’s NVP API makes it simple to integrate payments into your application. As the merchant, your web application constructs an NVP string and transmit it via HTTPS (HTTP Secure) to the PayPal authorization server, and PayPal sends back an NVP-formatted response that your web application parses for the information relevant to the payment. Figure 1-1 shows this basic request and response workflow, which is typical of just about any web application.

Figure 1-1. Typical NVP request and response

The request identifies:

• The name or method of the API operation to be performed and its version

• PayPal API credentials

• Operation-specific ...