I am asking this as I am attempting to create a game library and I am kind of new to Socket programming and I was wondering if it is best that I use netty or plain old Socket.io for this. And when attempting this I just need an idea of how I should go about mixing TCP/UDP together within my framework for this section of what I am working on.
It seems you already picked netty, at least as tag. With that framework you do not do socket programming yourself. Go through the documentation and learn to focus on event handlers: What should happen when a message is received via the network?
Consider such messages simply to be events, just like a mouse click or keyboard input.