Its very good framework to develop any client server based application, mainly it provides a ease of developing any network based applications. we have used netty for developing protocol framework. Where we implemented a platform on which any other protocols can be developed. It provide the easy ways of integrating with sockets and callback systems, easy to debug and easy to understand was able to achieve very good performances with less resource, it has both tcp and udp communication support it also provides callback - event driven networking feature

Netty provides a non blocking I/O, and is very flexible and easy to use. It's also a very good fit if you want to write applications based on your own protocols. Using for websockets i found netty a pleasure to work with.

The async IO, Java NIO integration. Ability to configure and optimize all aspects down to the lowest network bits.