14.0. Introduction

Web services allow you to exchange information over HTTP using XML. When you want to find out the weather forecast for New York City, the current stock price of IBM, or the cost of a flat screen TV on eBay, you can write a short script to gather that data in a format you can easily manipulate. From a developer’s perspective, it’s as if you’re calling a local function that returns a value.

The key behind web services is platform-independent communication. Your PHP script running on Linux can talk to someone else’s IIS server on a Windows box using ASP without any communication problems. Likewise, you can talk to a box running Solaris, Apache, and JSP using the same sets of tools and interfaces.