For an introduction on Ajax please see the following articles:
Ajax is a client-side technology for creating interactive web applications.
XMLHttpRequest object is used to perform GET
and POST requests and the server can send back a response that can be processed
in the browser.
Click on the other hand is a server-side technology that can handle and process incoming Ajax requests and send a response back to the browser.
It is also possible to write custom AjaxBehaviors (covered later) that renders the client-side code necessary to initiate Ajax requests and handle Ajax responses and errors. In fact once you become familiar Click's Ajax handling, you will likely create custom AjaxBehaviors to streamline and encapsulate your client-side code.
In this chapter we'll look at the Ajax support provided by Click. There are two basic ways to handle and process Ajax requests:
AjaxBehavior - AjaxBehavior is a specialized Behavior that enables Controls to handle and respond to Ajax requests
Page Actions - Page Actions was covered earlier and provides a simple way to handle and respond to Ajax requests