C# How can I make sure that required UDP data gets to the client/server?

Question

I have been recently writing a UDP server for a 2D shooter game I am making in C# and XNA for PC, which will update and send world data, entity data, chat data .etc when required.

A question recently sprinted into mind when I was creating a way for players to change their weapons; what would happen if in the occasion the packets send to the server requesting a weapon change were lost? This question then made me think of another question; how can I make a way for the client and server to acknowledge receiving certain packets or blocks of data?

So, I came up with the following simple looking solution to tackle this problem :

1. Server sends packet(s) which require acknowledgement.
2. Client receives the packet(s) and sends an acknowledgement packet.
3. Server checks whether or not the client acknowledged the data. If the client has not, resend data.

The proposed solution looks pretty good, but what would happen if in the occasion that the acknowledgement packet gets lost or if anything unintended happens to it?

Would a better solution to this problem be to create a server and client which use TCP and UDP; where TCP is used for data that needs to get there and arrive in order / in one peace, and UDP for data that needs to get there fast and can cope with loss or error?

If a TCP/UDP server and client is a better choice, what are the risks and how would I go around to implement that?

Thanks.

Answer 1

You need to be using TCP if you want to ensure packets are delivered. UDP does not guarantee delivery, but TCP has this built into the protocol.