C# 4 and .NET 4

asP.neT Web forms ❘ 1155
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The complete code is compiled and cached ready to process subsequent requests.
HTML is generated and returned to the user.
In web applications the process is similar, although no dynamic compilation is required as web applications
are precompiled by definition.
The code-behind file generated for you in the PCSWebSite1 web site for Default.aspx is initially very
sparse. First, you see the default set of namespace references that you are likely to use in ASP.NET
web pages:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
code snippet PCSWebSite1/Default.aspx.cs
Below these references, you see an almost completely empty partial class definition for Default_aspx:
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
}
Here, the Page_Load() event handler can be used to add any code that is required when the page is loaded.
As you add more event handlers, and so on, this class file will become increasingly full of code. Note that
you don’t see the code that wires up this event handler to the page — event handlers are inferred by the ASP.
NET runtime, as noted earlier. This is due to the AutoEventWireUp attribute — setting this to false will
mean that you will need to associate the event handlers in your code with events on your own.
This class is a partial class definition because the process outlined earlier requires it. When the page
is precompiled, a separate partial class definition is created from the ASP.NET code for your page.
This includes all the controls you have added to the page. At design time, the compiler infers this partial
class definition, which allows you to use IntelliSense in your code-behind to reference controls on your page.
asP.neT server Controls
Your generated code doesn’t do very much yet, so next you need to add some content. You can do this in
Visual Studio using the Web Form designer, which supports drag-and-drop in just the same way as the
Windows Forms designer.
You can add three types of server controls to your ASP.NET pages:
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HTML server controls — These controls mimic HTML elements, which will be familiar to HTML
developers.
Web server controls — This is a new set of controls, some of which have the same functionality as
HTML controls. These controls have a common naming scheme for properties and other elements to
ease development, and provide consistency with analogous Windows Forms controls. There are also
some completely new and very powerful controls, as you will see later. Several types of web server
controls exist, including the standard ones such as buttons, validation controls for validating user
input, login controls to simplify user management, and more complicated controls for dealing with
data sources.
Custom and user controls — These controls are defined by the developer and can be created in a
number of ways, as discussed in Chapter 41.
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