I have a project in Flex (client) and Java red5 that I would like to move to jquery for the client. I would like to reuse some parts of the Java server-side code, and use Java's jQuery support.
Are there other solutions that I could use for the communication with the server?
Yes, I've read that http://www.playframework.org is an excellent framework for building Java-based RESTful web services. This way, you can easily integrate jQuery and JSON requests with your Java web service.
This site, http://coffeebean.loicdescotte.com/2011/01/how-to-export-objects-to-json-with-play.html, has a great example of how to export content as JSON.
As for the jQuery itself, check the doc's or start with something like this: