An additional change is required: an ASP.NET AJAX ScriptManager
server control must appear somewhere on the page before the AJAX server controls appear in
terms. In our scenario, a ScriptManager server control was added to the MasterPage
ControlsBook2MasterPage.master so that it is always present.
CHAPTER 2 ?– ENCAPSULATING FUNCT IONALITY IN ASP.NET 79
Figure 2-12. The AJAX Extensions Toolbox node
This worked great in terms of only updating the
tag and not reloading the whole
page, but if you enter fairly large values for X and Y, such as 200 ?— 200, several seconds will pass
before the table renders without providing any visual queue as to what is going on. This could
cause the user to click the button multiple times, thinking that the first click didn??™t work.
ASP.NET AJAX UpdateProgress Server Control
In building this sample, we immediately saw the value that the ASP.NET AJAX extensions
provide in terms of quickly adding AJAX-style functionality to an existing web page. To take the
AJAX example to the next level, we added an UpdateProgress server control to provide a visual
cue to the end user that work is occurring. This is a very important design requirement in building
effective AJAX-enabled web applications.
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