This chapter covered the object essential to Ajax, the XMLHttpRequest object in both Gecko-based browsers and Microsoft Internet Explorer. In addition, the differences between synchronous and asynchronous requests were described, along with the care and feeding of both types of requests. The question of how to handle the XML retrieved was described through the use of the XML Document Object Model.
The ever-present Really Simple Syndication was then covered as a potential source of XML. Finally, the ultimate source of XML (one which you might already have), web services, was described along with SOAP.