.NET^* Class Library for PayPal NVP API

The NVP API was created in response to developers' complaints of the complexity of the SOAP API. While communication with the SOAP API is done via XML packets exchanged with a web service, communication with the NVP API is done with name-value pair strings posted and received through http requests. Instead of a complete object consisting of all possible properties, each API call requires only the minimum number of parameters be transmitted. Unfortunately, this simplification introduces its own set of complications.

Based on the successful SOAP API class library, Encore Systems created an NVP API class library that simplifies this API and alleviates the new complications. Since the NVP API is all string based, there is no type checking on parameter names or values. A simple typo can lead to great difficulty in finding errors. Our class library defines constants for all API call parameters. Through Visual Studio Intellisense, parameters can be selected from a list while developing the payment solution. More detailed information is available on the NVP API Class Library demo site.

• Designed to run under Medium Trust for use in hosted environments.
• Each API call is encapsulated in its own .NET object.  Just add a the required name-value pair parameters and call the Post() function. The request is posted securely, server-to-server using .NET HttpWebRequest and HttpWebResponse classes.
• Data objects are defined for all PayPal enumeration types allowing simple population of DropDownLists.  Includes States, Countries, Currencies, PaymentActions, CreditCardTypes, etc.
• An API credentials encryption utility is included to safely store Username, Password, and Signature in the Web.Config where they serve as a default for all API calls.
• Installing the class library creates Visual Studio templates for creating web sites, Windows forms applications, and for adding the class library to existing web sites or applications.  The templates are available in both C# and VB.
• Includes a Visual Studio template that creates a diagnostic tool with documented source code showing every possible API call.  Try any possible combination of property settings on API calls to see what PayPal's response is.  Cut and paste the examples to get a quick start on your application.

*For .NET 2.0 or higher.