Over the last ten years, eBay has emerged as a platform where people can buy and sell practically anything. With more than 135 million users worldwide, eBay is a thriving online marketplace. Best of all, eBay isn't constrained by HTML. By using eBay's web services APIs, members of the eBay Developers Program can hook into the eBay platform using XML to integrate eBay into their own applications.
Like many web services, the eBay API comes in multiple flavors. There's the original XML-over-HTTPS POST interface, a format that's quite similar to REST. There's also a newer, more fashionable SOAP interface, which uses the Doc/Literal format.
Both have their own benefits and weaknesses. Pure XML is easy to produce and consume on any platform, something that's vital given the shaky state of PHP's SOAP support. However, SOAP has the advantage of eliminating the trouble of manually parsing XML into usable data structures.
