Datasheet

Just as with the earlier example, you can see that the resulting HTML is substantially different from the
original ASPX markup.
After you type in some text and click the button, the same process is more or less repeated: the web server
receives the request, the page is parsed, and the result gets sent back to the browser. When you click the
button, you cause a postback to occur, where any information contained in the page — such as the text you
typed in the text box — is sent back to the server. ASP.NET reacts to the postback by rendering the page
again. However, this time it prepopulates controls, like the
TextBox, with the values that were sent to the
page. Postbacks are an important concept in ASP.NET, and you’ll see more about them in other chapters,
including Chapters 4 and 9.
VWD hosts a lot more windows and tool panels than those you have seen so far. The next section briefly
touches upon some of the windows you’ll most frequently use when building ASP.NET web pages. All
of the windows mentioned are accessible from the main View menu in VWD.
Informational Windows
Besides the windows that are visible by default when you start VWD, there are many more windows
available in VWD. You’ll see most of them in action in the remainder of this book, but some are worth
highlighting now.
The Error List
The Error List, which is accessible from the View menu, gives you a list of the things that are currently
somehow broken in your site, including incorrect markup in your ASPX or HTML files and programming
errors in VB or C# files. This window can even show you errors in XML and CSS files. The error list shows
its messages in three categories — Errors, Warnings, and Messages — that signify the severity of the prob-
lem. Figure 1-12 shows the error list for a page that has some problems with its CSS and XHTML.
Figure 1-12
The Output Window
When you try to build your site using the Build menu, the Output window tells you whether the build
succeeded or not. If the build failed, the Output window will tell you why the build failed. In the com-
mercial versions of Visual Studio, the Output window is used for other information as well, including
the status of external plug-in programs. Building web sites is discussed later in this book, including
Chapter 18, which deals with deployment of your web site.
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Chapter 1: Getting Started with ASP.NET 3.5
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