Control Families
ASP+ provides a series of new server controls that can be instantiated within
an ASP+ page. From the developer's point of view, the advantage of using these
controls is that server-side processing can be carried out on events raised
by client-side controls.
The server controls provided with ASP+ fall into four broad categories or 'families':
- Intrinsic controls that create
HTML-style elements on the client. They can create intelligent controls that
automatically maintain state and provide extra features, or just plain HTML
elements.
- List controls that can automatically
produce lists of all kinds on the client. In conjunction with server-side
data binding, they can also populate the lists with data from databases, XML
files, etc. – using only a few lines of code.
- Rich controls output client-side
HTML, and in some cases client-side script as well, in order to create more
complex types of controls or interface elements on the client. An example
is the 'Calendar' control, which detects the browser type and creates corresponding
code to complement the features of that browser.
- Validation controls are non-visible
controls that make it easy to do client-side or server-side validation when
creating forms for the user to fill in and post back to the server. There
is a range of these controls, allowing complex validation to be carried out
easily.
All of these controls are designed to produce output that can run on any Web browser (you'll see this demonstrated
in several places within the book). There are no client-side ActiveX controls
or Java applets required. We'll look at each of these control types in more
detail next.