Although Java has earned a reputation for solid back-end performance, its history as a client-facing platform has been troubled. When Java first shipped in 1995, programmers could create GUI components with the AWT (Abstract Windowing Toolkit). This package attempted -- with only modest success -- to provide a cross-platform set of controls and widgets. But programs that relied on the AWT were unstable, barely portable, and not terribly attractive.

As programmers began turning away from AWT, Sun did the right thing: It went back to the drawing board. In 1997 it unveiled JFC (Java Foundation Classes), including Swing, an attractive and remarkably capable set of GUI components. Because the Swing components were written in 100 percent Java, though, they ran slowly. In addition, Swing applications did not look exactly like native programs.

To address these issues, a Canadian outfit named Object Technology International (OTI) developed a new GUI toolbox called SWT (Standard Widget Toolkit), which implemented controls using native code on each platform. When SWT paints a dialog box on the screen, it"s the same dialog box Linux, Mac OS, or Windows uses. It isn"t emulated, which means it"s speedy and uses native components.

IBM bought OTI and rolled its products into the Eclipse project, which is where SWT can be obtained today. Unfortunately, although SWT is easy to program and faithful to the native platform, it contains only a subset of what Swing offers. Nevertheless, OTI"s advances have made client-facing Java an acceptable reality after many years of trying.

Enterprise applications often rely on a Web-based presentation layer rather than a native GUI one, however. From the earliest days of enterprise Java, the core functionality for providing such interfaces has been JSPs, templates that contain a mix of static elements and Java code used to generate dynamic Web pages. JSPs are cumbersome, however, as they encourage mixing business logic with presentation markup.

In response, the open source community devised a solution called Struts, which has enjoyed rapid adoption since it was released in 2001. It made a much cleaner distinction between logic and presentation tags, and so was easier to use.

Recently, IBM, Sun, and other major vendors have been promoting JSF (JavaServer Faces) as the next step in this evolution. JSF has a rich component palette well-suited to the code generated by RAD (rapid application development) tools and interface designers. It also uses a more flexible model than does Struts. The ability to mock up JSF screens quickly will probably clinch its acceptance by the development community, furthered in part by the presence of Struts" lead designer on the JSF team at Sun.