Most attentive developers have been developing around interactive Web technologies since the late 1990s. Various technologies (for example, Microsoft Remote Scripting and opensource and commercial variations) have been developed without forming a critical mass of acceptance and use. Or perhaps the mass was big enough, but everyone was waiting for the spark of a killer application. Another factor that slowed down the adoption of more advanced client techniques was the lack of cross-browser support for them.
Today, the situation is
different from what it was only three or four
ago. Now about 90 percent of the available browsers support all the minimal requirements for implementing interactive Web applications, known as AJAX applications. In addition, the W3C is standardizing the
object, which is the necessary communication workhorse behind all existing platforms for AJAX. The
generation of Web applications will be based on a different mechanism: it is no longer, or not just, forms posted in a change of pages, but individual
for data and dynamic updates to displayed pages.
As a server technology aimed at the creation of Web pages, ASP.NET takes advantage of the opportunity for providing this much desired functionality. Script callbacks were the first Microsoft attempt to offer an API for building AJAX-style pages. Modeled after the classic postback event, callbacks are sometimes unnecessarily heavy and
An add-on to ASP.NET 2.0, Microsoft ASP.NET AJAX Extensions, shows the way ahead for AJAX applications as far as the ASP.NET platform is
. It integrates the AJAX lifestyle into the existing application model of ASP.NET, resulting in a familiar programming model with greatly improved and richer functionality.
The Microsoft Client Library for AJAX
Most of the power of AJAX resides on the client and is
calls and often kicks in and
The DOM represents the programming gateway to the page
elements, but it is not designed to provide programming facilities such as those you can find in a general-purpose library. Normally, the script tools you can leverage to
These extensions are coded using the base set of instructions that characterize the
files that form the Microsoft AJAX client runtime environment.