jabsorb is a simple and lightweight Ajax/Web 2.0 framework that allows you to call methods in a Java web application from JavaScript code running in a web browser as if they were local objects residing directly in the browser.
jabsorb handles all the details of marshalling and unmarshalling objects back and forth between the client and server so that you can focus on writing your application features.
jabsorb makes use of the JSON-RPC protocol for it's transport mechanism. JSON-RPC is a standard protocol and jabsorb can interoperate with other standard JSON-RPC clients and servers that may be written in other languages.
Starting with jabsorb 1.2, additional ORB functionality has been added, and it extends the basic JSON-RPC protocol to allow for passing data structures that contain Circular References.
Qwicket is a quickstart application for the wicket framework. Its intent is to provide a rapid method for creating a new wicket project with the basic infrastructure in place so that you can quickly get to the meat of your application rather than mucking with the plumbing of a wicket application. Currently, the system only supports spring and hibernate built with ant. Future plans include support for maven 2 and other persistence layers such as ibatis.
The Google Web Toolkit (GWT) has attracted a lot of attention lately as a way to make it easier for developers to add AJAX Web 2.0 features to their applications. Like other approaches, the designers of GWT have tried to insulate developers from having to deal with the underlying JavaScript, which implements these features. GWT achieves this goal of simplifying the creation of advanced client-side JavaScript widgets by generating them from Java code.
Stripes is a presentation framework for building web applications using the latest Java technologies. The main driver behind Stripes is that web application development in Java is just too much work! It seems like every existing framework requires gobs of configuration. Struts is pretty feature-light and has some serious architectural issues (see Stripes vs. Struts for details). Others, like WebWork 2 and Spring-MVC are much better, but still require a lot of configuration, and seem to require you to learn a whole new language just to get started.