Chapter 39
ASP.NET AJAX
Web application programming is subject to continuous change and improvement. In the previous two chapters, you learned how to use ASP.NET to create fully functional Web applications, and you may think that you have seen all the tools that you need to create your own Web applications. However, if you spend much time on the Internet, you may have noticed that more recent Web sites are significantly better, in terms of usability, than older Web sites. Many of today’s best Web sites provide rich user interfaces that feel almost as responsive as Windows applications. They achieve this by using client-side processing, primarily through JavaScript code, and increasingly through a technology known as Ajax.
This change of direction is possible because the browsers that clients use to browse Web sites, and the computers that clients use to run browsers, have become more powerful. The current generation of Web browsers, such as Internet Explorer 7 and Firefox, also support a wide variety of standards. These standards, which include JavaScript, enable Web applications to provide functionality far in advance of what was previously possible using plain HTML. You have already seen some of this in previous chapters — for example the use of cascading style sheets (CSS) to style Web applications.
Ajax — as you will discover shortly — is not a new technology. Rather, it is a combination of standards that makes it possible to realize the rich potential functionality of current ...
