HTML server controls

HTML server controls offer a variety of features, which include:

·        Programmatic Object Model -- you can access HTML server controls programmatically on the server using all the familiar object oriented techniques. Each HTML server control is an object and, as such, you can access its various properties and get/set them programmatically.

·        Event Processing -- HTML server controls provide a mechanism to write event handlers in much the same way you would for a client-based form. The only difference is that the event is handled in the server code.

·        Automatic Value Caching -- when form data is posted to the server, the values that the user entered into the HTML server controls are automatically maintained when the page is sent back to the browser.

·        Data Binding -- it's possible to bind data to one or more properties of an HTML server control.

·        Custom Attributes -- You can add any attributes you need to an HTML server control. The .NET Framework will render them to the client browser without any changes. This enables you to add browser-specific attributes to your controls.

·        Validation -- you can actually assign an ASP.NET validation control to do the work of validating an HTML server control. Validation controls are covered in detail later in this chapter.

One reason you might consider using HTML server controls in your own web form pages, is to leverage an existing HTML page's HTML tag or code base. For example, let's say you have an existing HMTL page that you would rather not re-write from scratch, but still would like to write some server-side code to access various properties of the various controls on the page. Converting an existing HTML page's controls to HTML server controls is simple: you just add the runat="server" attribute within the tag declaration of the HTML control. You might also need to add an id="MyControl" reference, where "MyControl" is your unique naming identifier for this object so that you can reference the object in your server-side code.