When building web pages, the visual parts in the Web Connection and Web Form Parts categories are used instead of standard VAST visual parts. They represent the various entities and controls that can be displayed by a Web browser. You cannot use any other visual parts in the user interface of a Web application. However, you can still use any VAST nonvisual part in your application logic. All of the features of VAST Platform, such as database access and communications, are available to your Web application.

The parts in the Web Connection categories are special VAST parts that have the ability to translate themselves into HTML code. At run time, instead of creating windows and user-interface controls on your screen, the parts generate HTML code that recreates your user interface in a Web browser. Incoming requests from Web browsers trigger the generation of HTML code by the application.

Because HTML and Web browsers support only certain functions, the Web Connection categories contain only a limited set of UI controls. Furthermore, when you build a Web page, you will find that the editing behavior of the Composition Editor is somewhat different from when you build an ordinary VAST application. Again, this is because the architecture of HTML does not support as many options for customization and precise placement. The Web Connection feature supports only what HTML supports, and it will not let you build a user interface that won't work on the Web.

Other HTML builders, such as FrontPage, may provide more robust HTML page creation. To use other HTML builders to create HTML pages, but still use Web Connection and Smalltalk to perform the data manipulation and presentation for the HTML pages, see Using Web Connection with other HTML Builders.