Also, unlike the ScriptManager, you
can actually have multiple UpdatePanel controls on the same page and even have nested
UpdatePanel controls within one another.
Using the UpdatePanel Control
To use an UpdatePanel control, you simply drag and drop it onto the design surface of
your web form (see Figure 5-5).
CHAPTER 5 ?– INTRODUCING SERVER CONTROLS IN ASP.NET AJAX 95
Figure 5-5. Placing an UpdatePanel control on a web form
However, as you know, the UpdatePanel control cannot function without a
ScriptManager control on the page. Additionally, the ScriptManager control must be
located before any UpdatePanel controls on your page. In other words, as you read your
source code from top to bottom, the ScriptManager reference should appear before the
UpdatePanel ones. Using the Tasks Assistant will ensure that it is placed correctly. If your
ScriptManager control is not present or is incorrectly placed, you??™ll get an error when you
try to open the page in a browser (see Figure 5-6).
CHAPTER 5 ?– INTRODUCING SERVER CONTROLS IN ASP.NET AJAX 96
Figure 5-6. Error page when the UpdatePanel and ScriptManager controls aren??™t properly
configured
The UpdatePanel control contains a designer surface where you can place HTML.
Pages:
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170