Chapter 5. PHP and Web Distributed Data eXchange (WDDX)
"Beam me up, Scotty!"Captain James T. Kirk, "Star Trek"
The preceding chapters have focused primarily on parsing XML documents with a strong emphasis on producing content for web browsers. Although accomplishing this is no mean featin fact, it's one of the most popular ways to use the XML/PHP comboit's just the tip of the XML iceberg.You'll remember from my opening remarks that XML provides constructs to encode any type of information in a standard, machine-readable format. This makes XML the ideal vehicle for information exchange over the web. All that's needed is an encoding format that is understandable to both sender and receiver and that can piggyback over standard Internet protocols (HTTP, SMTP, FTP, and so on).That's where the Web Distributed Data eXchange (WDDX) comes in. WDDX provides a standard format for creating XML-based data structures designed for easy transmission across the Internet. These WDDX data structures are largely platform-independent, and they can be decoded and used by any application that understands the WDDX format.Over the next few pages, I will be examining WDDX in greater detail, demonstrating how it can be combined with PHP to encode and exchange data across different systems and platforms.This chapter marks the transition from merely parsing XML data to actually using XML as the vehicle for other applications. In addition to detailed descriptions of how PHP can be used to create WDDX structures, I'll also be demonstrating some real-life applications of the technology to illustrate its usefulness and versatility.