TCP server - client communication app design

Question

I want to build TCP server-client apps for communication

> server app will run on windows server

> cross platfor client app will run on Windows & Linux

- one requires individual building or compilation for each platform that it supports,

OR

- one can be directly run on any platform without special preparation

> server should able to listen multiple clients on tcp port using separate thread for each client

> communication between server-client can be a (bi-deirectional)

- simple text message trasfer with acknowlesgement

- file transfer with akcnowledgement

what type of architecture i should use for project server & client?

can i build server in c# & client in c++?
is there any similar existing project which i can use?