Use XML to Build Services Cheaply Using PHP and MySQL

eb services are all about two things: XML and WSDL. When you build a Web service in a commercial platform such as Microsoft .NET or J2EE, you are building a smart server that can describe itself with WSDL, be invoked using a HTTP-Get, or SOAP, and return an XML payload.

But these platforms are expensive, of course. Some companies have (and will continue to) balk at the expense of implementing Web services. The problem is that, as XML and Web services are generally thought to go hand-in-hand, many ill-informed managers will dismiss excellent, low-cost opportunities to capitalize on XML.

It's a grave mistake: You can build XML delivery servers without writing or deploying Web services. And you can leverage the magic of representing data in XML, meaning that, amongst other things, you can provide many different presentation styles without changing the data. You simply use an XSLT stylesheet to generate the HTML as desired. For example, if you have customers that want to see the same data but present it in their own styles, you do not need towrite two different applications—you can simply write one to retrieve the required data and present it as XML and then use two different XSLT stylesheets to present the data to each customers.

This article will step you through building such an XML delivery server using PHP and MySQL, both of which are open source and free. In addition, the software will run on an Apache platform, giving you an end-to-end open source experience.

The example application I'll build in this article is for a company that provides sports data and statistics to the Web sites of different newspapers and other media companies, who want to present league standings in a way that is appropriate to their audience and style.