I'm new in the Java world and I'm totally confused with the sheer number of Java server-side technologies. I need to build application with Java on the server side and Flex-AIR on the client. All communication between them must be on sockets and in AMF format.
Which technology would be suitable for this?
I think tha given your constraints you should be looking at Blaze: http://opensource.adobe.com/wiki/display/blazeds/BlazeDS/