Both on the desktop and on the Web, widgets have become a highly sought-after commodity. A widget is a mini, self-containing application that performs a specific purpose. Programs like Konfabulator (www.konfabulator.com) offered users a platform to run widgets on their computers. Ranging from newsreaders to eBay feedback monitors, these widgets provide useful information to people that want them. They are applications that require little to no setup and perform only their allotted function.
On the Web, most widgets were primarily limited to static DHTML widgets, designed to emulate operating system controls such as menus, structure trees, and toolbars. While these widgets provided a means to emulate traditional applications, they didn't offer much more than that.
Thanks to the capabilities of XMLHttp, web widgets are beginning to change to incorporate data manipulation and retrieval with DHTML, creating rich web widgets that normally are found only on the desktop.
In this chapter, you will create four web widgets using PHP, ASP.NET, DHTML, and Ajax: a news ticker, a weather widget, a web search widget, and a site search widget. The following sections will walk you through the creation of these widgets and how to apply them to your web page.