At JavaOne 2006, Ajax emerged as the most popular technology and Java developers were actually going crazy about it as hundreds lined up for each and every session which had Ajax written in it. It might seem a bit amusing but it is expected that the hype generated by Ajax is going to move beyond the tech community. The time is not far away when one would see managers and customers asking for their applications to be Ajaxed.

The more complex issue would be actually implementing Ajax as no real Java developer could develop an application without using a framework and it would be a matter of time before hundreds of Ajax frameworks sprang up. The major concern with frameworks is that one could lock up the applications into the framework or adopt a framework that is not suited to the needs.

One needs to look out frameworks which claim Ajax enabled because they include a popular Ajax Javascript in their distribution. My friend Harshad Oak has come up with some frameworks that he believes would serve well in the long run and the factors that he relied on were firstly, already established and secondly, promoted by a major player:

Google Web Toolkit - Build AJAX apps in the Java language: Google Web Toolkit (GWT) is a Java software development framework that makes writing AJAX applications like Google Maps and Gmail easy for developers who don't speak browser quirks as a second language.
http://code.google.com/webtoolkit/

dojo: Dojo is an Open Source DHTML toolkit written in JavaScript. Dojo aims to solve some long-standing historical problems with DHTML which prevented mass adoption of dynamic web application development.
http://dojotoolkit.org/

Yahoo! User Interface Library: The Yahoo! User Interface (YUI) Library is a set of utilities and controls, written in JavaScript, for building richly interactive web applications using techniques such as DOM scripting, DHTML and AJAX.
http://developer.yahoo.com/yui/

Direct Web Remoting: DWR allows Javascript in a browser to interact with Java on a server and helps you manipulate web pages with the results.
http://getahead.ltd.uk/dwr/

Spry framework for Ajax: The Spry framework for Ajax is a JavaScript library for web designers that provides functionality that allows designers to build pages that provide a richer experience for their users. It is designed to bring Ajax to the web design community who can benefit from Ajax, but are not well served by other frameworks.
http://labs.adobe.com/technologies/spry/

Mochikit: MochiKit is a free lightweight JavaScript library.
http://mochikit.com/

Script.aculo.us: Provides you with easy-to-use, compatible and, ultimately, totally cool JavaScript libraries to make your web sites and web applications fly, Web 2.0 style.
http://script.aculo.us/