Integration Guide

Express Checkout Integration Guide August 7, 2012 61
PayPal Name-Value Pair API Basics
Executing NVP API Operations
Encoding and decoding methods for URLs
Related information:
"URL Decoding" on page 64
List Syntax for Name-Value Pairs
The PayPal API uses a special syntax for NVP fields defined as lists.
The NVP interface to the PayPal API requires a unique name for each field. In the API, lists
are prefixed by L_. To identify an element within the list, use the offset from the beginning of
the list, starting with 0 as the first element. For example, L_DESC0 is the first line of a
description, L_DESC1, is the second line, and so on.
NOTE: Not all lists follow the L_ prefix convention; however, all lists start with 0 as the first
element.
Executing NVP API Operations
You execute a PayPal NVP API operation by submitting an HTTPS POST request to a PayPal
API server, or by using cURL or another mechanism to provide secure access between the
buyer’s browser and the PayPal API server. For example, you might implement a system in
which the buyer’s browser remains a client of your server and your server becomes a client of
the PayPal API server.
Language Method
ASP.NET Encode System.Web.HttpUtility.UrlEncode(buffer,
Encoding.Default)
Decode System.Web.HttpUtility.UrlDecode(buffer,
Encoding.Default)
Classic ASP Encode Server.URLEncode
Decode No built-in function. Several implementation examples are available on the
Internet.
Java Encode java.net.URLEncoder.encode
Decode java.net.URLDecoder.decode
PHP Encode urlencode()
Decode urldecode()
ColdFusion Encode URLEncodedFormatstring [, charset]
Decode URLDecodeurlEncodedString[, charset])