I'm trying to write a server for a chat program. I want the server to have a tcp connection with every chat user. Is there way for the server to have multiple tcp connections at the same time without creating a socket for every connection? And if yes, how?
1 Answer
No. Unlike UDP sockets, TCP sockets work are connection-oriented. Whatever data is written into a socket, "magically" appears to come out of the socket at the other end as a stream of data. For that, both sockets maintain a virtual connection, a state. Among other things, the state defines both endpoints of the conntection - IP and port numbers of both sockets. So a single TCP socket can only talk to a single TCP socket at the other end.
UDP sockets on the other hand operate on a per-packet basis (connectionless), allowing you to send a receive packets to/from any destination using the same socket. However, UDP does not guarantee reliability and in-order delivery.
Btw, your question has nothing to do with python. All sockets (except raw sockets) are operating system sockets that work in the same way in all languages.
3 Comments
Malt
You better use TCP for data as well. Implementing reliability and order in UDP is not straightforward. Without these features, data will be lost or arrive out-of-order
Malt
Why don't you want to open more than one socket? There are ways in all languages for working with multiple sockets.
Jan Gimmler
I don't want a user limitation for a chat room. I already tried to generate a socket per user, but this ended in a big chaos, so I'll use UDP in the moment. Maybe I'll come back to TCP later.
