C# 4 and .NET 4

1210 ❘ ChaPTer 41 Asp.net feAtures
Page.Theme = Session["SessionTheme"] as string;
}
else
{
Page.Theme = "DefaultTheme";
}
}
}
// base call
base.OnPreInit(e);
code snippet PCSDemoSite/App_Code/MyPageBase.cs
This event handler checks the session state for an entry in SessionTheme and applies the selected theme if
there is one; otherwise DefaultTheme is used.
Note also that this class inherits from the usual page base class Page. This is necessary because, otherwise,
the page wouldn’t function as an ASP.NET web page.
For this to work, it is also necessary to specify this base class for all web pages. There are several ways of
doing this, the most obvious being either in the directive for a page or in the code behind a
page. The former strategy is fine for simple pages but precludes the use of custom code behind for a page, as
the page will no longer use the code in its own code-behind file. The other alternative is to change the class
that the page inherits from in the code-behind file. By default, new pages inherit from Page, but you can
change this. In the code-behind file for the theme selection page shown earlier, you may have noticed the
following code:
public partial class _Default : MyPageBase
{
...
}
code snippet PCSDemoSite/Configuration/Themes/Default.aspx.cs
Here MyPageBase is specified as the base of the Default class, and thus the method override in
MyPageBase.cs is used.
Web ParTs
ASP.NET contains a group of server controls known as Web Parts, which are designed to enable users to
personalize web pages. You may have seen this in action, for example, in SharePoint-based web sites or on
the My MSN home page: http://my.msn.com/. When you use Web Parts, the resulting functionality is
as follows:
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Users are presented with a default page layout that you supply. This layout consists of a number of
component Web Parts, each of which has a title and content.
Users can change the position of the Web Parts on a page.
Users can customize the appearance of Web Parts on a page or remove them from the page completely.
Users can be supplied with a catalog of Web Parts that they can add to the page.
Users can export Web Parts from a page, and then import them on a different page or site.
Connections can exist between Web Parts. For example, the content displayed in a Web Part could be
a graphical representation of the content displayed in another Web Part.
Any changes that users make persist between site visits.
ASP.NET supplies a complete framework for implanting Web Parts functionality, including management
and editing controls.
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