I must write a multiplayer pong game for the school. Where are thousand of rooms and where two players can go in to a room and play together and collect points. I programmed the Pong game using Java (LibGDX). How can I do the Network part. I searched the web. And I came across Kryonet. Is there something better? What should I google. On the Internet there are a lot of those questions. And no good answers. I hope that this most questions can be answered.

If someone has actual Open Source network game links, tutorials, books, network tutorial, etc. All this would help everyone.

Thank you.