Although the java.net.Socket and java.net.ServetSocket give me powerful networking capabilities I wouldn't want to go through the nitty gritties of creating and managing my own sockets and threads.
What open source Java Frameworks are available to create/deploy a Highly Scalable Multithreaded Client/Server Network Application?
I've had success with Apache MINA (http://mina.apache.org/) in the past. It's been pretty easy to get started with and performance is fairly decent.