How to Build a Network Layer in Unity

I wrote a blog post to record how I built a network layer in Unity.

>> https://alexddhuang.github.io/2019/08/06/how-to-build-a-network-layer-in-unity.html

 

You shouldnt use tcp for networking in a game.

 

I know UDP is better, but the new networking package (based on UDP) of Unity is still developing and unstable. Besides, my game will not have a heavy dependence on the speed of networking, so TCP is enough for me.

 

We use the steam low level API, its also stand alone these days.

https://github.com/ValveSoftware/GameNetworkingSockets

 

Depends the game. Fast-paced games would typically use UDP while slow paced strategy games would use TCP.

 

Depends on the number of units etc.

 

Certain types of games TCP is perfectly fine for, and it solves a lot of issues you have to handle yourself in UDP.

 

While I personally strongly prefer UDP (because it is lightweight and flexible), I can see some cases where a game could use TCP. Obviously TCP would not be right for fast paced FPS games. TCP could work with games that are slower paced, though.

The advantage of TCP is the developer does not need to worry about making sure each packet got there and in order. If you have a lot of stuff to send, you need it delivered in order, and you don't care about performance, then TCP may be an option.

If performance matters more than ensuring packet delivery, use UDP. Also, developers have the option to implement their own lightweight packet ordering code and packet confirmation code into their network layers (if needed) with UDP.

Here is a link to Sockets for anybody interested in building a network layer from scratch. The Socket class can use TCP or UDP.
https://docs.microsoft.com/en-us/dotnet/api/system.net.sockets.socket?view=netframework-4.8

 

This is a good explanation. I prefer UDP generally, but it was a non-trivial amount of work to on top of UDP implement connections, optional reliability, message fragmentation, small message combining, packet ordering, and dropping duplicate packets. That's stuff you mostly get for free with TCP.

 

Library I linked above allready have reliable UDP impemented. Difference from TCP is that you can choose how to group your reliable channels, so that entities that do not relate do not need to wait for a resend.