I was curious to explore the capabilities of Reverse Ajax. That's when I created this simple chat application using Spring/DWR/Ext JS.
From my experience, I can easily say that DWR is easy to learn and configure, especially when you are planning to integrate with Spring on the application tier. DWR has a powerful API to perform all relevant operations, right from accessing page script sessions to util classes for sending updates to the client.
Simply, drop the .war file in your web/app server. All dependencies are available in the archive itself. The only external reference is 'servlet-api.jar', which is part of the default lib in all latest containers. The source is packaged separately. Once deployed, the url to access should be: http://[server_name]
If you are trying to figure out what 'Kabootar' means, it's hindi for 'Pigeon'...