Major Features of Aspnet Server Controls

When you develop an ASP.NET Web Form, you can use the following type of controls:

■ HTML Server Controls You can manipulate these controls at the server-side. Before dispatching a form to the client, the ASP Engine converts them to the equivalent HTML elements. These controls are included in the System.Web.UI.HtmlControls namespace.

■ Web Server Controls (also known as Web Controls or ASP.NET Web Form Controls) These are the new generation's controls developed by Microsoft. They have many useful built-in features, and a standard set of properties. In the HTML or .aspx file, these are typically referenced with an asp: prefix such as asp:Label, asp:Button, or asp:TextBox. Besides the form-type server controls such as labels, button, and dropdown, there are a number of special-purpose controls like the Calendar and AdRotator controls. The ASP Engine also maps these controls to standard HTML equivalent controls before dispatching the page to the client.These Web server controls are available in the System.Web.UI.WebControls namespace.

■ Validation Controls This set of controls provides Rapid Application Development (RAD) features for automatically checking the specified validity of user inputs.These controls are available in the System.Web.UI .WebControls namespace.

■ Custom Controls You can develop your own server controls by extending an existing control or group of controls to provide additional functionalities.There are two versions of custom controls:Web User Controls and Web Custom Controls. The Web User Controls are easy to develop, and are typically stored as .ascx files.The Web Custom Controls require in-depth knowledge of Object Oriented Programming and the Common Language Runtime (CLR).These are stored in compiled form as assemblies.

In this chapter we will provide an overview of these controls. Before we introduce you to the ASP.NET server controls, we need to focus your attention on a number of procedural issues involved in developing a Web form.These issues are the following: Collecting Data using HTML Forms, State-less ASP controls versus State-full ASP Net controls, the role of PostBack, and In-Page Code versus Code-Behind.

Note_

In an IIS environment, the ASP and ASP.NET can run side by side. If you install ASP.NET, your existing ASP applications will continue running. The IIS uses the ASP Engine to process the .asp files, whereas it uses the ASP.NET Engine to process the .aspx files. Session states and application states are not shared between ASP and ASP.NET pages.

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