Introduction: Hacks #87-100
PayPal's Web Services
application programming interface (API) is the means by which you can
interface directly with the PayPal platform to build applications and
web sites that leverage features on the PayPal web site. Essentially,
this means that you can integrate your order-processing and
customer-service systems with the payment information stored on the
PayPal web site.
No longer are you bound by the patchwork services afforded by
services like Instant Payment Notification (IPN)
[Hack #65]
and
Payment Data Transfer (PDT) [Hack #85] .
Instead, the API provides a more seamless link between your
application and the PayPal engine, allowing you to write slick,
robust order-processing applications to help grow your business.
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Currently, you cannot use PayPal's API to process
credit card payments directly from your site. Your customers must
still visit the PayPal web site to send payments to you, but you can
subsequently use the API to retrieve the details about such payments,
including those funded by credit cards.
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The geek-impaired might not immediately see the benefit of writing
more code to essentially duplicate the functionality that exists on
the PayPal web site, but here are some specific benefits to consider:
Individual merchants can automate administrative tasks they do
repeatedly. Large merchants who conduct thousands of transactions a day no longer
have to log into PayPal to review their transactions, view specific
transaction details, or perform refunds [Hack #91] . This allows customer care
representatives to work more efficiently. Third parties can provide solutions to small or large businesses.
Some solutions require customers to pay via the PayPal web site, but
you can provide some services in which PayPal is never seen by the
user. Therefore, you can make it appear as if you are providing the
payment service (e.g., Mass Pay [Hack #96] . In addition, most of the
administrative PayPal functionality can remain on your site.
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You might be wondering at this point exactly how API, IPN, and PDT
differ. In simplest terms, IPN and PDT are notifications initiated by
PayPal (in the form of web requests) that let your server know when a
transaction has completed. The API, on the other hand, is initiated
by you and allows you to execute core PayPal functions from your
application, whenever and however you like. These technologies can be
used together for further automation.
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Due to security concerns, the API is limited to a subset of the
things you can do on the PayPal site. Specifically, you can do the
following things:
Search for a transaction with the date, name, email, and other
parameters [Hack #94] . Retrieve the details of a single transaction [Hack #93], given the PayPal transaction
ID. Refund a payment [Hack #91] (in
full, or partially). Make payments from your account to other accounts using
PayPal's Mass Pay service [Hack #96] .
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A little programming experience will be extremely helpful in making
use of the hacks in this chapter, most of which were written for
Visual Studio .NET. See the "Database Coding and
Platform Choices" section of the Preface for more
details.
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Most of the API functionality is usable by merchants as is, but there
are ways to extend the basic functionality to do wonderful things
that will make people mumble your name as you walk valiantly
by—which is the point of this book anyway,
isn't it?
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