Yahoo! Hacks

What Are Web Services?

The term web service refers to a set of standards for exchanging data between two systems. Though the systems may be built with completely different platforms, the web service protocols allow the systems to exchange information. For example, a service built with Perl scripts on a Linux machine could exchange information with a Visual Basic application on a Microsoft computer because both platforms can speak the common web service language.

Tip

Sometimes a web service is referred to as an application programming interface (API), a similar pre-Web concept. The terms are used interchangeably throughout this book.

The phrase web service has also come to describe a specific method of exchanging data using XML files sent over the familiar HTTP protocol. XML is a textual, structured representation of data that both computers and humans can read, and HTTP is the standard protocol for delivering content across the Web. Yahoo! has implemented a straightforward XML over HTTP architecture for its web services.

Yahoo! Web Services

Yahoo! has chosen a web services standard called REST for delivering most of its data. If you’ve used the Web, you’ll be familiar with how REST works. A specially constructed URL will return the data you’re after—just as the URL for a document on the Web returns that document. Instead of a web page (HTML document), REST requests return an XML document. The key to using Yahoo! Web Services is learning how to construct the proper request URLs.

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